Guys, we're one day out from the competition. That's right. Just one day out Let's go Tomorrow's a competition. I got to get my tanner day You got a thing. I'm gonna try to put up a two vlogs today just to get up so you guys can be caught up I'm excited. I'm pumped feel like my posing is ready. I feel like my body's ready guys This has been a great challenge. I have to say like To be able to do something like this to really focus my time and to commit something Especially these daily vlogs for 14 days straight and then being able to commit since February to do this competition Is amazing So I guess the the know I want to say before we get to the rest of this vlog is if you have a goal to do something Say that you got to do it But then actually put the work and the time in stay consistent take each step do it day by day by day by day by day And then you'll be able to stand that good feeling like now I feel great because I'm like wow I've worked so hard now to this phone a moment boom here I am so just keep that in mind when you're doing that. So I will see you guys All right boom so what I had to do is I changed into something just they don't like to share I really didn't care about just in case the tan messes up anything You forgot an umbrella just a case of rain.  But anyway, so I brought Some loose pink stuff sandals my outside the practice posing with the coach as soon as I get back So I brought my shorts with me. So I had to do a couple things But I'm gonna go get this umbrella and back. I'll see you guys at the bus station. I gotta get better at planning ahead of time This could have been real bad. I was lucky because they charge you if you go late for the tanning So happy I made it here on time It's the bus New Jersey transit like 14 bucks. So like seven bucks there back Harrington Park Number one, okay First homie got in the wrong bus guys got on the wrong bus. I was talking to this nice guy It's telling me about his life. It was really cool I was like, yo, I hope I hope I didn't miss my stop. He's like, yo, you actually got on the wrong bus.  It's now like 535. So of course it's got to be late Fortunately, I got at Uber. So we won't go ahead and go go there from now. So Yeah, Lee man I Somebody yelling So 119 is the number got a t-shirt ready to go pre-tanned practice posing real quick. I'll let y'all see it Then that's gonna be it Because I'm lean right now, but now I gotta get before my muscles have to be a little bit fuller because I'm already lean So that's what I'm gonna do. I'm gonna show you guys the food and I'll see y'all I'm messing up all of the place guys So I got home and then I figured out that I actually left my tennis shoes I wanted flip-flops because I got a baton on my feet. I left my tennis shoes At the five napkin place at the five napkin burger. That's the burger place you just saw me eat at So now I gotta go back there and go get it. So I'll be back Got it. All right guys last meal till the day A special day got my tan got my last meal gotta enjoy. I don't have a skinny cap for you guys Saturday, but I'm excited to see you guys tomorrow and you already know embrace the


What I'm going to be looking for here is several things, so I'm going to make sure that the device functions properly, goes high enough in the air, and I'll be recording the fuse burn time. So the fuse has to burn between three and nine seconds. Other things that we'll be looking for are like grass fires, tip overs, blowouts. We'll have the device still burns after testing.


Good morning everyone. We just open in prayer. Can someone be willing to open in prayer? Father God, we thank you. We bless you for this day, Father. We submit each one of us unto your loving hands. Father God, give us revelation and understanding to know what's teaching and use it for your glory, Father. In Jesus' name we pray. Thank you. So we'll just continue from where we stopped yesterday. I think we needed to, I was supposed to give you all the reference, right? So that's Acts 20, 22 to 24. I'll just read that out. So Paul says, And now compelled by the Spirit, I am going to Jerusalem, not knowing what will happen to me there. I only know that in every city the Holy Spirit wants me, that prison and hardships are facing me. However, I consider my life worth nothing to me. My only aim is to finish the race and complete the task the Lord Jesus has given me. The task of testifying to the good news of God's grace. So here that's where Paul is saying before he goes to many cities, he already knows that those are the things that await him, but he still goes in because he knows what God has entrusted to him. He knows the task that God has given him, and he is committed to completing that no matter what the cost is. And if you look here, he also says, I'm going to Jerusalem compelled by the Spirit. So this was the same question you were asking about, why did he go to Jerusalem, although he knew that. So he felt that the Holy Spirit was leading him there. If it meant that he would die, it didn't matter to him. Because I was telling you about the prophets books of Jesus God. Yeah. And you see, even in verse 23, the Holy Spirit wants me that these things are there in every city that I go into. So he recognizes that the Holy Spirit himself is revealing these things. But he continues to do it because he feels that that is his calling. He believes that this is calling. So yeah. Okay, let's go into today's. So yesterday we finished off the last part of Paul's life. After his first imprisonment into his second imprisonment and then his death. And then we looked at a little bit of like a summary of his life and then we moved into a look at the whole church right from the first century till our present day. We're going to be looking at what are some major events that took place. Before that we looked at a few scripture passages just to look at why it's important to look at church history. Why is it important to look at how God has moved in the past and the main thing from the scriptures is so that we can learn from the generations past, right? We have the testimonies of what God has done in generations past and so we can take that with us. We can believe God for greater things and we can have the faith to fight our present day battles also. So that was our main reason for looking through what all has happened in the past 2000 or more years. So let's start with the beginning. So the first century is when Jesus comes. So we look at AD. So there are different ways of the way time is looked at, but AD is one of the most common things. Nowadays people also look at CE and BC. So CE is the Christian era and BC is the before Christian era. That's another way of saying BC and AD. So BC is before Christ. AD is Anodomni which is the year of the Lord. That is the year Jesus was born. So AD was developed in 525 AD by a monk named Dionysus. And so since then it's been used as a way to look at time. Online students are all able to hear me. Okay, there's some construction work going on here. So I don't know how much of that is picking up. Yeah, you're allowed to hear me. Okay, thank you. Okay, so when we're looking at these early initial dates, we don't have the exact dates because it's more an estimate or an approximate kind of date. Some dates will be specific where we know like a historian has recorded something or something like that, but the other dates will be approximate. And the dates given here will be the start and end dates of when people began their ministry. So it's not their birth and death, but the start and end of their ministry. So Jesus was born around 10 BC and or 3 BC somewhere between that time between 10 to 3 BC. And then he was crucified in AD 30 or 33. So based on when he was born about 33 years after that. So we're using AD 30 as the approximate year of his death. And from there, all of the other things we look at. So the day of Pentecost based on the fact that we think that Jesus died in AD 30 and was raised up from the day in AD 30. Then the day of Pentecost also happened in AD 30. So that's when the church was birthed. That's when the Holy Spirit was poured out and from there the church began. AD 44 is when Herod Agrippa dies. So if you remember Herod Agrippa in scripture we see there's a passage where he gives a speech and people are really amazed by his speech. And they say this is the voice of God, not a voice of man. And then because he doesn't acknowledge God in that God kind of like he's he dies at that time. And it's God's judgment on him for not acknowledging God in that. And so after that is when Barnabas and Paul start their first missionary journey. That's recorded in Acts 13. So Acts 12 is where Herod Agrippa's death is recorded and Acts 13 is where Barnabas and Paul begin their first journey. AD 52 is when the apostle Paul arrived in India. So like Thomas arrives in India. Let's just look, I just put that up on a map so that we can see. Okay, so this is the area that Thomas ministered in. Okay, so we have he arrives in Malabar. So that coastal region is called Malabar and the Coromandel Coast in India. And that's where the church began. So we have a very close to Jesus's Jesus's ministry. The church in India started like that's quite amazing to have such a long history of Christianity. Every time people talk about Christianity being a Western religion or coming from the West, although that definitely has had an influence on the church in India. The start of the church in India is rooted in the apostles itself. So that's really like something for us to like really be grateful for that we get to sharing that. AD 64 is where the emperor Nero was the emperor of Rome started persecuting the Christians. Okay, so AD 66 to 68 is when Paul and Peter under emperor Nero's rule is when they are believed to have been killed.  And it's a huge fire that goes on for about six days before they're able to put it out. And in those six days out of 14 districts in Rome, 10 districts have been destroyed by the fire. So it was a huge fire and once that happened Nero blamed Christians for the fire and he used that as an excuse to then start persecuting Christians. So it was really like a very big time of persecution for Christians. He would use their bodies as human torches in his garden basically to start fires there. So this is where there's more persecution that's happening from the government. So before this, the church was facing persecution. We read so much about it in the New Testament, but most of that persecution was coming from the Jews. But here it's where it starts to come in from Rome itself, from the government itself. Which means it's more powerful also because they rule over that whole area. AD 70 is when Jerusalem is destroyed. So there's a Roman emperor named Titus and he destroyed Jerusalem and at this time the Jews revolted against the Roman authority. But Christians on the other hand did not take part in the revolt and they escaped out of Jerusalem. And they went to a place called Pella which is east of the Jordan River. You can see it on the map here if you're logged in. It's okay, no pressure to log in but if you want to see the map it's there. So there's a place called Pella. So from Jerusalem which was destroyed they all escaped to Pella. In 1890 so that's close to the end of the first century. There was a council of Jamia and this is where it's recorded by Josephus who is a Jewish historian. He recorded that the final Hebrew Old Testament was agreed upon. So until this time there were many books that were being used in the Hebrew scriptures among the Jews as well. So there were the books that we have now but there were also additional books that were written by other people. So during this council they finalized saying these are the specific books we are going to accept as part of our scriptures. The other books will still have authority because they have a lot of history. They have a lot of Jewish teaching but they will not be the doctrine that we follow. So they distinguish between what is doctrinal and what is helpful for their faith. The Jews themselves also had the same set of books and the Christians adopted the same set of books as our Old Testament. So this we'll see the difference between the Protestants and Catholics is where there's a slight difference. So some books that were not added in our Old Testament continue to be in the Catholic Bible because they had decided to keep those books in their scriptures at a later council that met in I think it's the 4th or 5th century. So AD 95, the book of Revelation is written. AD 96 to AD 150 is where the New Testament books start to be more fully recognized. So all of these epistles and all of the letters that the different apostles had written were being circulated among the churches. So they started to be recognized as important documents for the church's faith. AD 96 to AD 150. And further to yesterday's discussion we were talking about how do we know that these were circulated to all of these churches. So even in archaeological findings in all of that they found documents from different letters, so different parts of these manuscripts in different parts of like geographically they were distributed. So the same manuscript or copies of the same manuscript were found in different places. That's how we know that the letters circulated among the churches. AD 98 is when the Apostle John dies. So 95 he writes the book of Revelation 98, he dies when he's about 100 years old. AD 99, the whole New Testament is complete. So all the books that were written in the New Testament are complete by AD 99. So there's also like all of the writings of the New Testament are very close to Jesus's time of ministry. So people who are defending like a lot of people question the authenticity of what is written in the New Testament. How do we know that it is true? One of the ways is how close was it to the actual events because the further away it goes, the more chances that that history will be distorted. But the closer it is, we know that there were people who would have been alive during Jesus's time. They would have seen his ministry. So if other people were writing and they were writing things that were false, there would be other people who could question that. So people who saw Jesus's ministry could see what was being written by the apostles and could verify whether it was true or not true. So that's how we can one of the ways we know that all of this is very authentic and trustworthy. AD 100, the first Christians are reported in these three countries, Monaco, Algeria and Sri Lanka. So we'll just look at that. So I didn't put this on the map, sorry. So Monaco is in North Africa. Monaco is in France, like the southeast border of France. So the country of France is there. Monaco is like a small thing just near the sea. And Algeria is on the other side of the sea in North Africa. And then Sri Lanka is in south of India. No, I didn't put that map in because I couldn't find a good map for these places. But so Monaco and Algeria are on two sides of the sea that divides Europe and Africa. So the Tyrian sea is there. And so they are on both sides of that. And then Sri Lanka is in south of India. Then second century. So we finished those first hundred years after Jesus' birth. We come to the second, next hundred years. So persecution didn't continue at the same kind of intensity as it was initially, but it was there within the church. But the other danger that came in was from inside the church, which was the danger of heresies. So heresies are where there is wrong teaching that is not in line with what is believed about God according to scriptures and what is doctrinally accepted by the church. So it was something that was against church doctrine that was being taught within the church. So we look at some of these heresies. The first one is Gnosticism. So Gnosticism, there are various things that Gnosticism covers because there were many different things that were being taught and all of those things got clubbed in and they were called Gnosticism. The first one is the secret knowledge. So they said to be saved, you have to have a secret knowledge that will come from God and only then you can be saved. That was one of the teachings. The other was that the material world is evil and only the spiritual world is good. So they elevated the spirit over the material world and everything that is material, everything that is physical was considered evil. Everything that is spiritual is considered good. So it was a mix of Jewish, Christian and Greek thought that came in. So they started mixing up all of these things and teaching it as Christian doctrine. So that was the problem that the church was facing. So the church responded to this with teaching to make sure that Christians were not going away from the truth. So some of the things that were affirmed within the church was that Jesus was fully incarnated and became a human being because Gnostics were teaching that the material world is evil then how could Jesus become something evil? That was the question. If the material world, the physical world is evil how could God kind of adopt, how could he become flesh? So the church taught about the incarnation of Jesus about his physical death and the resurrection of the body. They talked about how God has revealed himself through history in humanity. It's not like just a spiritual revelation, it is through human history and about the importance of Jesus' death and resurrection for salvation. So Jesus like physically died and there is a bodily resurrection and this is so important for us for salvation to know that Jesus was not just some spiritual being who didn't die. Basically he couldn't have died if he didn't have a body. And so if he didn't die and if he didn't rise from the dead then salvation is not possible for humanity. So this was some things that the church was making sure was corrected and they were preaching that to preach against Gnosticism. Another heresy is Masinism. So here there was someone named Masin within the church and he picked a few books from the scriptures and said that these are the scriptures that we should be following. The others are not as important. So this was rejected by the church leaders and he was excommunicated from the church. Montenism. So this was charismatic movement where they were saying that they were receiving new revelations, new prophecies and they were passing judgments on other Christians. So this was another heresy. So during this time because there were heresies there were Christian leaders who were responding to the heresies and they were writing books. They were teaching to make sure that true doctrine was retained within the church. So this is called the age of the apologist because that's when the apologist started to do their work or that whole idea of apologist came into being because they had to defend the faith. So Iranians and Justin Martyr are some important apologists from that time. And we look a little more at some of the writings that came out at the time as we follow through. AD 107. There's a polycap. I believe he's the first bishop that's appointed because we haven't looked at any other bishops but he was appointed as the bishop of Smyrna. So he was actually discipled by the Apostle John. So directly by one of the apostles he was discipled and then he becomes the bishop of Smyrna. We'll just look at that. So Smyrna is here as you can see the Mediterranean Sea. Smyrna is here in this border and then we have other different places that Christianity had spread. So we see Ephesus here, Thyatira, Sardis and that's where the first bishop was appointed. AD 108. Ignatius of Antioch is martyred. So actually as I was reading this, all of them have, each of these people have such powerful stories of how they impacted the church, how they stayed true to the faith right up to death. So all of these people were given opportunities to denounce their faith and to save their own lives. But they chose not to do that and to be martyred for the sake of their faith and it is because of that the truth within the church has been preserved. If they had denounced their faith, they're denouncing the truth that they had been preaching. Then it didn't give other Christians the confidence to say that what these people were preaching was true and we can hold on to it. So for the sake of preserving that truth and preserving the church, all of these people were willing to give up their lives. So we see Ignatius of Antioch. This is the Antioch that's in Syria, which is where Paul's home church. We talked about that same Antioch. And Ignatius was also a student under the Apostle John. So Ignatius did a lot of writing. A lot of these early church fathers did a lot of writing. And so when we look at his writings, it gives us some understanding of what the early church was teaching. There are seven letters that he wrote to the churches covering the deity of Christ, the Lord's table, so communion, the structure of the local church, having bishops, having elders, having deities. How do you have all of these people in authority? What is their role? What is their function? All of those things. So this was important for, because the church was just, all of these local churches were being raised, there had to be leadership overseeing the work that was done. So to make sure that that was properly organized, was understood by the churches, each person knew their function, knew their role. So all of that were things that he wrote about. And then finally, he was taken to Rome and he was put to death by wild animals. So the Colosseum where they would put prisoners or they would put criminals to death by use of animals, that was how he was put to death. AD 125, Aristides, he writes the first Christian apology. So the first time there is a written defense of what we believe and he gives it to the emperor of Rome, Hadrian. AD 150 to AD 190 is where the New Testament books start to be recognized as authoritative and as part of the scriptures that the church will follow, that Christians will follow. So most of the books are recognized. There are only a few more books that are still not decided on. So they're still trying to decide should this be included in scripture or should we just keep it as outside scripture but informative for the church. AD 150 is where the Latin... So the first translation of the Bible, right? The Latin version. So it was translated from the Greek Septuagint into Latin. So the first Latin version of the Bible. AD 155, Justin Marto writes his first apology. So previously was the first apology that was ever written and now Justin Marto also writes one. So this is where it's believed that the age of the apologists started. So after that, there were many other people who followed this. Theophilus, Athenogaris, Irenaeus, Turtilian, all of these people who followed. It was kind of like they trained one another. The apologists would train the next generation and would train and train and that's how they were learning under one another just like there were disciples training the following leaders of the church. The apologists also were leaders in the church but this important function of preserving truth was given to them. AD 155, we also see the Bishop Paulicap is martyred at age 84. So he's the one who was the Bishop of Smyrna. So sorry, I lost my... Yeah, at age 44. So Paulicap in turn, you see this thing of mentoring, raising up leaders all of that has been so important because with each generation that's dying out, there have to be leaders to take over. So Paulicap trained the church historian Irenaeus and so Irenaeus was able to then take over leadership within the church. So a lot of Christian history, we know so much about this because of someone named Eusebius. So he had written a history of the early church until AD 323. So so much of what we know of the church is because of his recordings of the history of the church.  So there were lots of people who were coming to an understanding of what does the Trinity mean until then they only knew Yahweh, that's for the Jews, but for those from outside, from the Gentile background to understand what is how the Father, Son and the Holy Spirit related to one another. What does it mean to have the Trinity? Are there three gods, is there one God, all of these things? So the church leaders had to themselves have a revelation and understanding of what it means and then to be able to explain it to the people. So he talks about this and talks about the Father and Son having the same substance that is both being divine and both sharing in divinity together. Not one being lower, one being higher than the other. AD 183 to 186 is Irenaeus, so Irenaeus was trained by the bishop Paulic up. He becomes a bishop of Lugdanum and he writes against heresies and his book actually covers a lot of Gnosticism, so it addresses a lot of the things that the Gnostics were teaching. And Irenaeus is one of the strongest witness of his times to the apostolic age because Irenaeus was trained by Paulic up and Paulic up was trained by John. So he has a lot that he's able to share about the apostolic time because he was so strongly connected to it. AD 190 to AD 200. So Clement of Alexandria, he's a Christian theologian and he starts to teach new Christians in Alexandria and he writes three books talking about the Christian faith. So the basics of the Christian faith for new believers. AD 190, Pattainus of Alexandria comes to India in response to there's a request for Christian teachers and so he comes to India. So with that we come to the end of the first 200 years of the church and then we start the next century. AD 200, we have the first place that becomes a Christian state. So it's called Edessa, you can see it on the map here. So Edessa was right here above Antioch and above Judea and Syria. So it's right up here and this is the first place that was fully Christian. So meaning like politically Christian. So it's a Christian established state. And Carthage and Alexandria become leading centers. So we go to the next map. So Carthage and Alexandria were in North Africa and they become important places of Christian theological teaching and a lot of the leaders in the church come from these two places. So Origin, Tertullian and Clement of Alexandria are few of the people who come from there and will actually write a lot and teach a lot on the Christian faith. AD 202 to AD 211, the Roman emperor Septimius Severus starts to forbid conversion to Christianity. So before it was just like persecution towards those who were reaching a following Christ. But now it's saying you're not allowed to become a Christian. That's coming from the government again. So the Roman emperor does this. But in spite of that, Christianity continues to spread. AD 200 to AD 220, Tertullian. So again from Carthage, he writes a lot of several books and tracks. One of them is called Against Praxis and it talks the most about Christianity. One of the most thorough descriptions of the Trinity is given in his writing. So this is where like the basics of understanding of who Jesus is. Like astrology, Trinitarian theology, all of these things come from these people who wrote at that time. It's not things that we've developed now in the 1900s or in 2000. All of our understandings of the Trinity, of Christ, of his divinity, all of that come from these early writings. 245 origin. So one of the Christian apologists and also from Carthage. He responds to a writing by someone named Celsus. So Celsus was someone who had actually written 70 years earlier and he had attacked a lot of what Christians believe. Basically saying that Jesus could not have had a miraculous conception. He could not have been born as a human because bringing again the material world is evil.  And then he kind of came against everything about Jesus' life, about Jesus' childhood, his ministry, his death, his resurrection. He was also telling Christians don't follow Christianity, become a pagan. He was a philosopher so he was using a lot of philosophical thought to try and convince Christians that what they believed made no sense. So his writings were continuing to be a threat to the church. So after 70 years, he's written 70 years back, Origin writes a response to what he has written. And actually Celsus' writing is not available, we don't have his original writing, but Origin's response basically he quotes a lot of what Celsus said and then he responds to it. So that's how we know what Celsus had written in his criticism of Christianity. AD 248 is when Rome celebrates a thousand years of reigning over so much of Asia Minor and North Africa. But at this time they're starting to have some threats against their reign. So a lot of what we're reading about Christianity spread is within Rome itself. So when Jesus came, it was under the Roman Empire and Christianity continued to spread under the Roman Empire. But it did spread like we read, it spread to India, Sri Lanka, so outside of the Roman Empire as well. AD 250, Emperor Decius makes this commandment that everyone needs to offer pagan sacrifices. So kind of making everyone in the empire follow the Roman gods to show, to honor the Roman gods. And he says you have to offer the sacrifice and you have to show a certificate to prove that you offer the sacrifice. So there's a lot of persecution for those who are not following that order because it's coming straight from the emperor himself. And a lot of Christians actually give in to because of the persecution they give in and they go and sacrifice to the pagan gods. So now the church has to deal with what about these people who have done this? Do we still accept them into the church when they want to come back or do we say that they are not allowed anymore because they've given in? So that is one big question that the church has to deal with. Then there are intellectual attacks that increase against the church. So someone named Poffery writes against the Christians and talks against the apostles, the church leaders, the gospels, the Old Testament. So there's lots of, like all of the things we see nowadays is not something new to Christianity. Like we see so much writing against our faith, against whether it's in India or outside India, there's so much that's coming even internationally. But this is what the church has faced from the start. That's one thing for us to not only recognize that God continues to work in spite of these things, right? Even as we read this like wherever persecution, wherever challenges were coming in from, whether it was other people around the church, whether it was the leaders, the government itself, Christianity continued to spread, God continued to move. That is one thing to be encouraged by. The other thing is that there is so much truth that is preserved, that has been preserved by these early church leaders that we can go back to. And that we can also find confidence in. I remember when I was working that there was somebody who came and he was part of a cult and started to talk to me about certain things in the Bible saying, ask me questions about it. And usually when it's a cult, they will have supporting scriptures for whatever they are saying. And there are very specific ways of interpreting scripture. And I was a believer but I wasn't so knowledgeable about scripture. So I remember it was really confusing for me when he was saying all of those things to know always what I believe, really true is, have I just been convinced by somebody that this is what scripture means or this is what is true? But for us to find confidence in the fact that all of these challenges were there and responses were written to it based on scripture. And those responses kept the church going. The truth preserved the church and the church continued to grow. So what we believe, we can have confidence in what we believe because we know that it is truth that has lasted through so many challenges and people have continued to hold on to it. AD 300. Anthony the Great is from Egypt and he's the first monk. So this was a movement that started where people who were really serious about following God would leave their cities and move or wherever they were living and move into the desert. And would basically adopt a form of asceticism where they were giving up the world and going to seek God in a place that was free of distractions, free of worldly distractions. So this started the monastic movement which is a powerful movement within the church because we'll see later on as the church gains power politically. These people had rejected all of that and had gone primarily to seek God. And so they preserved a lot of the truth of just following Christ even when it's not attractive, even if it's not politically supported to just follow God. So he started this movement and they are people who we refer to as the church fathers or the desert fathers. We see among these monks that there was a lot of power in prayer, there was healing, deliverance, miracles that they experienced. So that power of the church continued to be preserved among these people. Although it was still being seen at this point within the church it was still being seen but among the monks we have records of that. So other important leaders who continued in this monastic life, Anthony the Great, Paccomius, Athanasius is pretty well known. I think we may read about him later or maybe I'm not sure. Hilarion, Ambrose, Jerome, Augustine, Benedict of Nursia, Gregory the Great. So lots of like very impactful leaders came from this movement. In 8300, North Africa becomes a key Christian center and Egypt alone has a million Christians by the end of the third century. So that's where the center of Christianity was, North Africa. And the role of the bishop continues to grow because the bishop oversees large areas of the church. They oversaw provinces within the Roman Empire. So the bishop starts to get more and more powerful because they're overseeing so many churches. So end of 300 years and then we start the next century. AD 303, Emperor Diocletian, begins to persecute the church and his intention is that Christianity should be completely removed from the empire. But he obviously fails, praise God, and the church continues to grow. AD 311, there's a new group of people called the Donates that rise up. They are following the leadership of one of the bishops within the church. The bishop named Donates Magnus and he leads a part of the church that breaks away from the larger church. Now the main disagreement here between these two sexes should leaders who rejected the faith under this persecution that happened, right? We did AD 303, this Diocletian persecuted the church. So there were Christian leaders, church leaders who had fallen away from the faith at that time. They've given up their faith to protect their lives. So the Donates and all those who followed him said such leaders should not be accepted back into the church. We cannot follow such leaders who gave up their faith under a time of persecution. Whereas the rest of the church was still accepting leaders back if they came back to the church and they were allowing them to continue to lead the church. So this is where the first split within the major split happens within the church and that division in the North African church continued for 300 years. And the church in that is weakened a bit because of this division that happened. Finally, we'll see in North Africa that Christianity reduces and is lost from that region. If we look now at North Africa, it's primarily a Muslim region. AD 312, this is where Christianity now begins to get political power. Until now it's just been a thing that was a movement among people, right? There was no support. In fact, there was opposition from the government. Now the government itself starts to promote Christianity because Constantine comes into power. In 312 is where Constantine is in power and he's going to battle against another emperor within the Roman Empire whose name is Maxentus. And as he's going to battle against this emperor, he has a vision and in the vision he sees the sign of cross and it says in this sign you will conquer. He sees that in his vision. And he wins this battle and so he says he attributes that to the Christian God because of the sign of the cross. And he starts to support Christianity because of that. In AD 313 is when the edict of Milan was issued and through this edict Christianity was legalized in Rome. Until then it was illegal. So he legalizes it and they start to rebuild church buildings that were destroyed. They start to restore things to the church that had been confiscated from the church during the persecution. So he starts to bring all of those things back. Okay. So we can stop here. Anything you want to share or talk about? I think we have a minute. Okay. We'll continue from then next week on Monday. We'll continue in the 4th century. Thank you. Have a good week.


It's noon. Let's get started all the way through this section today. But who knows? So can somebody summarize where we left off on Thursday? We were defending a house and deciding what that meant as far as what we had to defend against. That went into what our goals would be and now our policies and how we're going to structure those policies. So we came up with policies, what we wanted to be allowed or not allowed in our house scenario and we discussed and came up with mechanisms to try to enforce that. And then we talked about some of the pros and cons of those mechanisms. Sometimes they didn't line up exactly or do exactly what we want, but they were pretty good nonetheless. What about the different types of security policies? How to actually define security policies? The policy language, what do we talk about policy languages five days ago right now? Yeah, so example was xml is a policy. So xacml is a policy language. And the idea there is you kind of have both world parts. Yes, there is some English natural language in there, but if your policy is explicitly defined in a machine readable format so that other systems can consume them and use them. Perfect. All right, so how do we know if our security policy is correct? What do we mean by correct? Yeah, so it does what we want it to do, right? So kind of similar thing when we think about our programs being correct or not, right? They do what they're supposed to do and what else? Is that it? Does it just do what it's supposed to do? It doesn't introduce any more. It doesn't do anything else that it isn't supposed to do, right? So you've got a door that lets you in if you have the key and that would do what it's supposed to do, but if the door just happens to swing open if you breathe on it, then it's probably doing more than you want it to do and so it's not really what you want, right? So how can we determine if our security policies are correct? Is this easy? Sounds easy, right? Do you know when your, how do I know when your programming assignments, your professors in class, how do they know when your programming assignments are correct? They use test cases, right, to do what? It produces the correct answers, it produces what it's supposed to produce as outputs. For all inputs? Not for all inputs. They test if certain outputs fail based on that kind of stuff, certain outputs pass based on the inputs and all that kind of stuff. Right, so the test cases are defined inputs with known outputs and the policy is essentially there that if your program has given this input, produces this output, then your program is correct. Does this prove that the program is correct? No. Can't test every case. You can't test every case, right? So there could be a case that you're not testing, which I know from a fact happens a lot of times in programming assignments, you say, oh I'm failing these test cases, why my program looks correct to me, we tap. I mean it's a black box approach, you actually don't see how the code's functioning, so technically you could be programming it to take known outputs and outputs, but you're supposed to know it, but can't handle situations outside of that selected situation. Right, exactly. So this brings up the case where you have, and I've actually seen some, well, not too much of this, but you could just write a big switch statement that if it sees this input, output this output, if it sees this input, output this output, so you haven't really built anything except to solve the past these test cases, yeah, in fact. Your security policy could be used for something that was unintended for a key to elaborate? You were expecting people to come through building, but it's not really different for their children.  It's a trojan horse idea, right, so something that does not look like a person that maybe now made a security policy, so what would that, what's the problem of the security policy there? Is it a problem of the security policy or is it a problem of the implementation of this policy?  You have to try to think how your program would be broken and etc., and so in both implementing the policy and the policy themselves, you have to try to be thorough and specific with it. Right, so yeah, so there's kind of, well, when you say, hey, only authorized people are allowed to enter or exit a building, let's say, going back to our building analogy, there's an implicit assumption in there that you can define, you can identify and know what a person is. Right, so this kind of is that idea about what if a dog, you know, real dog shows up, or what if a mechanical dog shows up, or what if a drone shows up, what if a human dressed up is one of these things. Right, so if we think, okay, if we want to talk about the correctness of our security policy, did we make any assumptions, so in our housing example, did we make any assumptions there, so we just talked about the people, defining what people. I assumed it was in the United States. We assumed in the United States, how does that change your assumption of the correctness of the security policy? Other countries are less civilized than ours, unanticipated events are now authorized persons that list might change more frequently based on what the government says in another country. Interesting, so yeah, we'll talk about that in a second, but we can generalize that, because laws are different in different countries, so we've been talked about authorizing fire personnel, law enforcement officers to enter our building, or our house, right, so that means change depending on the laws of the country. Well, going back to the dog, like the human in a dog suit, we kind of assumed that everyone is who they say they are. We assumed that a police officer is a police officer, firefighter is a firefighter. Yeah, so we assumed that we have some way of actually identifying that people are who they say they are, me, so yeah, so that's difficult, right? So somebody can, this actually happens when I get interviewed by FBI agents for security claims just for the students, they'll come and they'll be like, hey, I need to talk to you about something, so I'm like, oh yeah, I'm a federal agent, here's my, you know, my badge, okay, what am I supposed to do with this, like I'm not a, it's gonna be 100% fake, I'm gonna keep the card, I remember the person, but you know, I'm not going out and verifying that on some database that it's actually this person who they say they are, they have this badge number, I mean, all that could be fabricated for all I know, but I'm not saying anything crazy to them, so it's okay. What else, any other substance? For instance, there's like, you know, that we're in there only one country's law, so if you're talking about a house, it's a kind of situation, because I know there's some houses here that are literally on the border of a few different countries, and have to actually deal with a law that's literally in one country and once I pass it to another country, that's crazy. Yeah, I wonder if you get in trouble by moving goods across the borders, so okay, so you've got laws that are definitely more complex, you can even take the US case and say, well maybe the house is in the US and it's actually on embassy property, so technically that's not our sovereignty, and there's all other laws and things that apply here, I don't know, all kinds of crazy stuff there, so what other, what other assumptions? Yeah, so we had, we definitely assumed things about the environment, and if we were really serious that, hey, these mechanisms are key to ensuring our security policy, we need to know how those mechanisms can fail, and what assumptions those mechanisms are based on, because that is something that an attacker could potentially cut, so what happens if they cut the power to our house and our security system goes down and our awesome smart lock system also goes down, right, do the doors just wide open at that point, what happens? So kind of these, these, we talked about a couple of things, right, so we're assuming essentially that the policy is correct, so this kind of goes back to the people and being able to identify people, right, so there's an assumption there that the policy is correct, so how do we verify that the policy is correct, was that, so one thing would be test cases, like a program, so how would you create test cases in this scenario, what was that? How would you create a test case for this, like a program is easier, you have input, you have a program, you feed them, but to the program you say, if the output is what I expect, then the program casts this test case, so how can you do this for a security policy? Higher or somebody to do it for you, that's what I'm training you to be, so you can be higher. I wasn't going to say that. Higher someone to break in? Yeah, okay. You have to access the database, like you have a database that you're constantly getting validation and checks from. Validation and checks from where? Well, like you have a database or in the case of like how do you know this, our policy is correct, and you want to, you need to have store who are valid, like who are valid, so the policy is like, hey, go to check this database, like you said, you can't just say it without that. But how do you know that that policy is correct of stating that the people in the database aren't authorized users? Yeah, the back. So, if you have a policy and the policy is to try and prevent something from happening, then you should try to execute that because I think it's trying to prevent to see if the policy actually does prevent it. Well, does the policy itself actually prevent anything from happening? No. No, because the policy is just what? Words or a mathematical formula, right? A policy is just a statement of what is or is not allowed. So, we can think about this in two ways, right? So, we can use that idea, but apply it instead to a concrete implementation of the mechanisms enforcing the policy. We can instead take that idea and apply the threats that we've already thought about and work through in our heads, okay, would this policy counter this threat? Would this policy counter this threat? So, essentially the threats that we've already come up with can be our essentially our test cases to try to say whether the policy is correct in some sense. And remember, it's correct against our threat, what we consider we'll get into risk later, but it's all contextual, right? So, depending on where the house is located, we may have different threats that we care about. If I'm storing, like if you think of Fort Knox essentially as a house, right, that needs to be secured, they have a completely different threat model than you would have in your apartment, right? So, they're considering thinking about different threats than you are. So, we have the policy is correct. So, we can test the policy. If we have the policy written in a mathematical language, then what could we possibly do? Build the mechanisms described in the policy and test those? Is that kind of the same thing? Not yet. We can write proof. So, if it's mathematically described, we can try to actually prove that this policy is correct. What's the difficulty there? Was the response being able to do a proof? Yes. In general case or in a specific case. So, you could do this, right? But what's the difficulty? What are you trying to prove? Yeah. Yeah. So, it may not be, well, so you have to think. So, we've lifted the policy into kind of this abstract math language, right? So, we can manipulate the policy. What else do we have to lift into math? So, we have the policy is formally defined. What are we trying to prove? That doesn't work. We said it. Not thinking about mechanisms now, just policies. That is correct. That's correct, right? So, remember, talking about working is just different than correct. It's similar, but, right? But we want to prove that the policy is correct. So, we've lifted the policy into a mathematical language. What do we need to do with our notion of correctness? We need to actually be able to describe that mathematically, right? Because we can't prove something that we can't express in our mathematical formalism. And so, therein lies the problem, right? So, if we can accurately specify our notion of correctness in mathematical terms, and we're confident that that mathematical expression is actually what we want to prove, right? This is always the problem when it comes to using math and using formalism to try and prove something. You could prove that this system, this policy is correct. But if your correctness notion is not exactly what you want, you're still kind of the same problem. So, these are all different sides of the same coin that can help you think about this kind of thing. So, then, there's the other aspect that we've been talking about is that the mechanism actually implements the policy that we want, right? So, now we actually have a system, we've designed mechanisms to implement this policy. How do we know that those are correct? So, what do we care about with the correctness here? So, that the mechanisms you're using actually work for the policy objectives? Yeah, so that the mechanisms that we're using correctly enforce the policies. So, this kind of already assumes that the policy is correct, right? So, here we're just focused on, do these mechanisms actually implement the policy? So, how do we do this? So, we've talked about some ideas, but... So, how would we... How would you try to convince me that, yes, your mechanisms are correct? Well, just test case, like, take the house analogy. If you're trying to keep somebody out of the house, by using a key, you send people to the house to try to get in the house. Without a key, yeah. Or if you're trying to keep somebody out of your website, you send people there to try to get in. Yeah, any other ideas? So, we can maybe, similar to the test case, we can actually create real threats and launch them at the system, control threats that we control, right? And see whether they can bypass the mechanisms and ultimately bypass and invalidate the security policy. Is that all we can do? What's the problem with that approach? Oh, sorry, can I get it back? Yeah. I was going to say you have to make your weight and development. So, there may be correctness in the mechanism itself, right? That's a good point. So, we care not only does the mechanism enforce the policy, but does the mechanism actually do what it says it does? This would be, especially if you're buying something non-standard, right? So, if you're buying a lock for a door, I think you can be roughly safe that it does what it says it does. If you're buying some software security product that's telling you it's going to find every single intrusion into your database, that may be a claim that you want to verify or get some notion of how good it actually is. So, you can separate the marketing claims from what it actually does. It's a great point. So, yeah, so this, I don't know that I'd necessarily say that. I think you need to have a notion of correctness that the mechanisms are working together properly, right? And as you have more and more mechanisms that are interacting, now you need to verify not only do they each work correctly individually, but that collaboratively they also work together, right? You may have 10 different mechanisms, but if they all rely on, let's say, your security camera, then if I hack in your security camera and disable that, then the other nine mechanisms are useless, right? So, you want to understand these intermixings of these mechanisms. Can you say possibly in that the mechanisms themselves also need to be secure because if they're not secure, then they could actually be involved in security? Yes, I would say that, I would phrase that more by going back to the notion of correctness of the mechanism. Yeah, so the mechanisms do what they say they do and nothing more. I think that kind of encompasses security in there, but that's a great point, yeah. Yeah, you'd want to. So, a mechanism that is faulty or broken could, at the best case, is useless at the worst case that allows an adversary another avenue into your organization.  That would kind of be a good example there. Cool, so we can, so we talked about, we can actually instantiate, like pay someone, so this is consultants coming again, right? You could pay somebody to test your system to try to break into it, to try to violate a policy. What's the downside there? It's expensive. It's expensive, yes, that's probably, hopefully why a lot of you are in here and are going to be pursuing a security job because it's a field that pays a lot because you need a lot of expertise and how to bypass these things and you need this adversarial mindset. So, it's expensive, what else? Yeah. You can break something? They could break something, yeah, so you could actually maybe damage the system or cause something to go down, yeah. If they, like, report or tell the people this, that have made any various purposes before you're able to have it. Yeah, so there's trust, that's actually part of what you're paying for in your payment is you're paying not only for the form of the service but their silence of the results that they found. So usually as part of your agreement with the company, it would be confidential, but you have to imagine what's this coming, you know, maybe you're such a high-value target that it's worth them burning their entire reputation to break into your organization. I mean, I think we're assuming that they are more skilled than we are by the fact that we're hiring them, but how do we verify their correctness? Yes, there's actually a huge problem with hiring security consultants, is they can, just like the PR of some security product, can tell you it's amazing, it has 100% effectiveness.  Yeah, in the back. You have a policy for bounties, like for instance, if someone actually does hack and do it and they say, well, I found this, plug in your system and you pay them something. Yeah, that's interesting. So, we could, to generalize that a little bit, so we could maybe create some policy that said, hey, if you bring into our system and you do no harm and you tell us how you did that, if we agree with your findings and we fix it, then we'll pay you some monies. That can be a way to kind of open up, rather than hiring one person, you can kind of just leave that out there. What does it say about security of your system, that in general? So, these ideas of hiring or getting somebody outside to try to find a flaw in your system. Yeah. Reduce the risk. Reduce what risk? Of being incorrect. Of being incorrect, what was? So, of the implementation of the mechanism and security policy. So, if they do in what, so if they come back and say we didn't find anything, it would. Right. It doesn't guarantee it. It doesn't guarantee that there are no flaws in that implementation, but it does reduce the risk, hopefully, if they're credible and meet all the other stuff that we talked about, that they've reduced the risk that there is, that it's not correct. I see. So yeah, I think the way of, I wouldn't say it reduces the risk, necessarily. I'd say it increases your assurance that the mechanism's actually enforced your policy correctly. You may also say something about the company itself if they find something or don't find something, right? So, just because they can't find something doesn't mean somebody else or bad guys cannot find other ways. Yeah? I think that one of the issues of, so you build a whole system and you hire somebody to test it, you've already spent a ton of money in development and you don't even know if it's secure or not. Yes. Like, so why not build something secure up front? Yes. Do all that before you have to get to the point of penetration test? 100% agree. So, this is kind of, it goes back to what we talked about policies, right? We can think about the threats, articulate the threats against them and be explicit and argue that, yes, this policy will combat this. We can do the same thing with the mechanisms, right? I mean, we can kind of take an idea, okay, if the mechanism we're assuming it does X, Y, and Z, and if it does, then that prevents this threat. It prevents this other threat. So you can go through the threats that you've identified. And yeah, so going back, you want to do this at all stages, right? So you want to, you can analyze the security of the design of a system. You can, and we'll talk about all these different aspects. That's a great point. Yeah, so if your only idea of security is, hey, I'll build something and then somebody else will tell me later if it's secure or not, I guarantee you they will say it's not secure, right? You have to think of, and you have to think about this at every stage of the, say systems development lifecycle. So trust. Who do we trust? So if we put locks on the door and we say that these locks, so our policy would be something like only people with the key could access our house. So we talk a lot on Thursday about this means that we have to trust the people we give the key to, right? That they won't give it to anybody else. We have to make sure that we keep the key safe. Who else do we have to trust that I don't think we talk about? The person who made the lock. Yeah, why do we need to trust that person or company? What are you worried about with them? Make sure they don't have much extra keys sitting around. Yeah, that they didn't make an extra key that they have. So that's really good. So the person who made the lock, who else? People who have keys, who else? Anybody that would be locked out of their house? What do you do? We call it a lock set. Then what does the lock set do? Crawl through the dumps in the lock. Huh? Yeah, comes to your house and has professional tools to pick your lock, right? And let you into your house. Right? So what are you trusting there about your policies and your mechanism in respect to the lock set? He won't come back later and make himself at home on your own? Yeah, well, I guess you're assuming that they could do that at any point, right? Regardless of whether it's before or after you hire their services, right? But you're trusting, essentially, yeah. Yeah, you're trusting that they're going to verify that you actually lived there before they let you, right? I don't know. I think it probably varies state to state about what the actual requirements are. Maybe it's an ID that you can show that has your address on your driver's license. Again, we get into trust issues because then you have to trust that like, how does a locksmith verify that your driver's license is not a fake and a difficult problem. So there's trust built in, right? So why do we care about understanding the trust here? Yes, either so it doesn't conflict with our policy or that we're aware of it when we think about it and consider the threats, right? So maybe for our house, we're okay with trusting locksmiths, right? We would want to be okay trusting locksmiths and that is fine. That's part of our security analysis and we'll get to like risk, risk analysis, right? A tie value target may not want to do that. So they may want to get locks that are anti locksmith proof or something. I don't know if those exist, but you know you could try. Or you could add other mechanisms on top of that that would tell you if a locksmith was about to get in your your place. So mechanisms, we talked about different types of mechanisms. The one that we focused on a lot is technical, right? So this would be a lock, some piece of software, some part of the operating system. So what are other types of mechanisms? Do we even care about them? With TV on. And having toys coming from inside of the house that you're about to break in if you might be good to turn. Yeah, so it has some technical component, but it also requires a behavioral change on the part of a person, right? A person has to actually turn that on before they leave. Any other examples? Yeah. Do we have like a guard or someone watching it? So like a yeah. So some I know some communities will have this. They'll have a security person like driving around or don't vote the proper term for those people. I was going to say rent a cop, but I'm not sure where that falls on the correctness scale. Yeah. So you may and so then you're trusting that this person is actually going to do their job and actually drive around not saying what place is going to call in anything bad that they see. It isn't going to be bribed by some criminals to get free access to the whole place. Yeah. Absolutely. Yeah. So you're trusting kind of the judgment of that that person of when to escalate things. What other non-technical mechanisms do there be? Yeah. I think we saw this last week when we can have psychological mechanisms where you could sign stuff like the alarm systems that we built in here. Yeah. Yeah. So psychologically trying to that technically won't prevent or protect anything, but are trying to manipulate the psychology of your attacker to try to say like, I know you will get caught and that way that's a good example. Yeah. Maybe like so if you're like posting a Facebook when you're on vacation and it makes you a target it's not like you're doing that. Yes. So that would be so changing your behavior. Just I think about this all the time whenever I like call on a Uber to come get me to take you to the airport.   I told them I would be gone this weekend. Man, luckily I don't look like I have much. So yeah, and people would do this. There's I think bots that they can write and do that will track your location that you're posting from on Twitter. If it's not where it normally is though criminals will know, hey, you're actually out of town. And so they'll try to hit or rob your place then. The location. The location of the house because I think there's some house with a breakdown that you need to treat or something versus a silence. Yeah, so hiding information. So that would be a less technical. Maybe we have big bushes around the perimeter of the property so that people can't actually see where the house is. So they can't plan how to break in. What about anybody? There's somebody here who worked in a bank. Don't they call anybody out? I just I feel like so what so what were the what were the mechanisms in place to make sure you couldn't steal money from the tilt? Oh, I remember to the stage I killed my manager and we needed two keys to help her go. Yes. So perfect. Right. So I'm like this thing. I don't get pause. Not stop. No, this is great. So this is not really technical mechanisms. Well, the two keys are definitely technical mechanisms. But the fact that every time you went to the state, your boss had to be there. What does that ensure? That either one doesn't steal any of the money. Right. So this is the employee checking on the boss and the boss checking on the employee. Right. So this way is one of them is compromised or wants to steal money. Right. The other ones there to verify what happens. This actually happens a lot in a lot of different scenarios where you need two parties to do something or to authorize something. So that way they go a system of checks and balances. Any other ones you want to share?  So this was part of their policies. Right. It's not a technical thing. It's a procedure as part of the organization. Every day you're going to they're going to make sure that your amount matches. Right. What the machine says you should have and what's actually in there. Right. So they're keeping tracks. They do daily audits to make sure. And if it's off by even a cent. Right. You can get written up and you can get eventually fired from the job. Right. So they're building in procedures as mechanisms that are procedures and not necessarily technical mechanisms. Yeah. So in some places if you assume a sign that says they don't give you a receipt with your food then you get a free meal to notify the manager. It's because they want them running everything through the till so that they calculate how much money is supposed to be there at the end. If they're skimming money they don't put a transaction then get the food for the two. So the receipts are a secondary source for verification that everything's going through the till. Yeah. So that's yeah. So then they're incentivizing customers to demand receipts so that that way the teller doesn't accidentally forget to ring something up in which case the numbers don't matter. Yeah. These are all good. So yeah. So it's important to think about these things. Right. Because not everything can be technical. Right. We can maybe try to ensure that two people are there to open up a safe because we can force them to have two different keys that are farther apart than a human. Right. So it's not there's one person. If you've seen I don't know if this happened to any more but old movies when they launched nukes right it's always two people need to turn the key at the same time. Right. And so therefore that way one crazy person can't just launch well can't just launch nukes. Actually a new clear rushes the marine in the area and then the second officer imputes a bunch of nukes after after they have they went they lost the radio and the second mate said I'm not and that way he was like he is a lots of nukes. That's the only thing kept us from people here in the organization it was one guy who said no. That's crazy. Yeah. So yeah it's good you know good that we have these mechanisms in place. So we talked kind of about the correctness of mechanisms. So how do we know if our mechanisms are actually effective and what do we so kind of we talked about that they're correct that they do what they say they do and really what's the goal of a mechanism to do a job. They do a job to use to implement some policy. Right. So the effectiveness of a mechanism depends on the policy that you're actually using that you care about. And so there's three we're going to talk this actually going to help us we're going to build up some definitions that are going to help us later on when we talk about So if a mechanism. Well, so we'll just define these things. So a mechanism is secure. So you think about I think about different sets and different spaces. It's really all the book boils it down to kind of set theory which makes a lot of sense to me. So let's draw pictures. Although I'm a bad artist you're stuck with it. So All right. So let's say the policy has some shape that's circle ish. Right. So the policy defines what what is and isn't allowed. What is and is not allowed. So everything inside the circle is what allowed allowed and everything outside is unallowed. Right. So this is kind of another way you can think about the policy mechanism dynamic. Right. Is the policy defines what states are secure states and what states are insecure states. And we're using very I mean this is getting very abstract. Right. We're not defining what the state is. We're not defining we're just saying that the policy is a way to tell you whether the current state or whether a state is secure or not secure. Right. So in the house example everything inside the circle would be only authorized people are inside your house and outside that circle would be anyone who's not authorized is inside your house. So the mechanism carves out and kind of enforces some sub well some subset of the spaces that are possible. Right. So a mechanism essentially restricts what states the system can move between. So if oh that's not right. So if I have a mechanism like for our house example I don't know if it could let's say I hire a person why should I make up we actually make up. So if my mechanism is a subset of the secure states what does that mean about my mechanism. It's what it should be secure. It should be secure right as long as we start in one of these states. Right. The mechanism allows us to go anywhere in here well except there it allows us to go anywhere in here but does not allow us to go outside. So all of the states that the mechanism allows that the mechanism allows us to go into are secure. What's the problem. Not all of it's well not all the policy set is covered by the mechanism. Yeah there are other states that are secure that our mechanism does not allow us to reach. Right. So our mechanism in this case would be I think a restrictive would be a good word for that. Right. So our mechanism is actually restricting the states we could possibly be in. So the mechanism is definitely secure. Right. And it's secure because why. Some stuff of the secure set. That doesn't allow exactly. So you do think of it as it contains only the subset of the secure states or you could say that it doesn't allow us to access any insecure states. Right. Those would be the same statements. All right. So I would be one mechanism. The mechanism like this. What does that mean. So I wouldn't say access necessarily. So I think it's a trick that we want to want to talk about in terms of states. So it allows the state to transition into secure. You know. It's a secure state. But it also allows the state to transition to insecure states. Right. They are states outside the policy that this mechanism allows the state to be in. So a term for this is broad. So it's an overly broad mechanism. Right. It allows some things. It doesn't allow other things. So what now. What's the goal. What would be like a perfect mechanism. Yeah. Something that does exactly. Exactly. Perfect. So yeah. There's no way we would be able to draw this. But pretend that this is the best tracing you've ever seen in your life.  So if it's exactly identical. So all of the secure states are allowed by the mechanism.  This would be a precise.  Right. So why is this useful. It allows me on the problem. This allows us to establish our mathematical language. When we're defining what we. Yeah. So two ways. So a can allow us a precise way to describe whether the mechanism is implemented is precisely implementing the policy or secure with respect to a policy or as broad with respect to a policy. It also helps us think about policies and mechanisms right. And say like OK you know. It is this mechanism doing precisely what my policy wants. Is it more is it secure and restrictive or is it more broad. In the real world the likelihood of being so locks on a door. Yeah probably broad. Security cameras security system that you have to put in a code. Secure. When somebody just smashes the system or disables the power to the system. So. This kind of the double-edged sword here right. Is the real world is very messy and there are a lot of ways around. Your mechanisms. So. Most of them will be very broad. Right. Because that's just the nature of what we're doing. And so you have to think about OK. Maybe with respect to the threats or assuming that the power still works. Right. Then this mechanism would be secure or would be precise. So it helps us to think about these mechanisms. Right. What does assurance mean. Sorry. So let's go back. Sorry. David what would be a real world.  What would the policy be there. Yeah. So the policy of the panic room would be only. Like the family could be in there. You know you know no one's allowed to leave or something. That can be a good one. Although I'm sure there's ways into a panic room if you have enough time. And you could start them out. You could like. What was that. If it's on the second floor. Oh yeah. You could like helicopter like. I don't helicopter your cranes or whatever it is. Panic rooms. Right. That's interesting. Any other. The White House. But people. Well. There's even just a couple of months it was next. Somebody was able to run all the way to the front. It was a video game inside the house. That's true. If you didn't know. You crashed a plane into it during the Bill Clinton administration right. Or was it your push. When did the plane crash into it. I do not know. The pilot may have died but I think that would qualify as entry. But he only landed in the yard though. I was in the yard. It wasn't mine.  But there were the couple that went to the ball that weren't supposed to go to the ball. Some kind of like crashers. Like they crashed the ball. That was a little bit of a White House if I remember. So yeah this is kind of the problem. I was thinking maybe like if we checked each one of your ASU IDs. Before you turn in your exam. And we'd have to then verify. Also do an online lookup of your photo in my ASU system. And your photo there. But even then that's still a lot of 100% full proof. Because you could have just had somebody else take your picture and sign up right. So it all goes back to the root of trust.   Yeah probably not going to touch that. We should probably not talk about White House as an airport. Yes the problem with encryption as we'll get into it depends on who has the key. So it's all about key management at that point. I'd say okay so a secure policy.  If the policy is any authorized user can go in there. A secure mechanism would be you only allowing one, your one friend that you know inside your house. And you like hiring an armed guard multiple armed guards. And only that one person is allowed in ever. That would still be somebody to try to like dress up as them. And make sure you're struck to a certain degree. I mean it's all all kind of ways around that. So it'd be difficult. All right let's move on. But yeah so assurance. So going back to the question earlier about something decreasing risk or. So assurance is really and it's one of the three words I guess two words that makes up the title of this classic game number one official title is. So the idea there is how can we trust. So assurance is all about our understanding of a system and its security. So how can we trust that a system is secure. And how confident another way to think about it is how confident are we that the system is secure. So how do we trust? What should our trust be based off of proven results of what? Well it's an anti virus that catches at least one virus. Interesting point we will address anti virus at some point. Is it too much of kind of a cross in to say I mean in our personal lives and such like that we know that trust is earned and trust is very easily broken. So in that type of way trust kind of builds upon itself and also when you when it is lost. Yes and no I think the way it breaks down is me thinking you know if you are working with someone for a long time and they don't do anything untrustworthy your trust in them increases. Right if you have a system that's running for a long time and you haven't been breached does that mean your assurance that the system is secure should be high. It should probably not because especially if you have no detection mechanisms in place you're probably being owned and you don't know it. That was actually a complaint I heard from I was at that conference last week on Wednesday. I think one of the generals said they got major pushback in the military when they started applying intrusion detection systems and they said well why why don't you want these things. Well they come up with all these alerts that were being scanned and all these attacks when you wanted to get a system but yeah that's the problem. Yeah but now we have to deal with it. Like yes you should have already had to deal with it now you're just aware of the problem. Well I would say if you trust you want to you know you want to make the policies the as in depth as you can create the mechanisms to implement those policies test those systems continuously to keep building trust in your system. Yes so that's what so yes the overtime but it's not just something that naturally occurs over time right so for instance I mean you can be you have pretty reasonably I don't know there's always still problems but at least compared to let's say early 2000s even let's say windows I mean I'm gonna pick up Linux but windows is a good example right early 2000 windows had tons of vulnerabilities in the kernel that would allow remote there is code red melissa virus all kinds of these worms and viruses that were spread through email over time these become much more rare because microsoft developed time and resources into securing the kernel level code and so over time you can have more assurance that yes there will still be vulnerabilities in the windows kernel but they're not as prevalent as they are essentially nowadays so because they have a process and a continuous process in place about continuous improvement and refinement so yeah going back here if you're thinking through and creating your policies to make sure that they are actually aligned with your organization's goals that they are specific and appropriate for your organization that you've thought through and they counter the threats that you're concerned about if you have mechanisms that you have a good assurance that yes these actually enforce and implement the policy that you want and that you test at these mechanisms that you test them over time and that you have some feedback loop in there so that when you see a new threat or a new when your system is compromised you can go back and address your policies to change everything response to that so then over time yes you would you would increase your assurance in the system yes you clarified something a few minutes earlier talking about assumption now you're talking about trust and in my mind trust is just a special case of assumptions are you are you making a difference like you described the difference in your mind between is it just a human element that we trust people when we make assumptions about machines and systems that are inanimate like what's the difference because we can make a stuff like it just seems like the same idea yes i'm trying to think in my own head i'm roughly using them interchangeably i don't know that there's a distinct difference i can call without stopping my head if anybody else has one would say that assumptions assumptions you're usually are usually and should be explicitly stated right so you can say something like this mechanism is precise to this policy assuming a and b and c and d conditions are all true trust is a little bit more nebulous concept but yeah essentially you are trusting something you're assuming that they're going to do something in a certain way so they're definitely related potentially more implied trust is a little more implied whereas assumptions at least in this case are more yeah that's what i would yeah that's kind of how i would think about it but you really need to analyze your the trust inherent in your system to understand and state your assumptions yeah i'd also say assumption is kind of more of a binary thing and trust is more of a gradient right like you could maybe try to quantify well i trust i don't know the locksmith right the trucks locksmith so i'm at 60 or 70 percent or something so um you can have some notion there and i guess it does get into when you have systems of systems right so you could maybe trust that another system is or you can have trust in your certain mechanisms and how much they work up to a certain threshold um so yeah so we've been talking about this right so you're talking about how can we actually trust our own system right so i guess that's another thing you're not assuming that it's secure and then doing something else here saying well how much do i trust that the system is actually implementing the policies i want and is keeping people you know safe and enforcing my organization's goals can you quantify this what i mean by quantify level or something like that what kind of certification level trust certification who's going to give me that certification how much money you have i'll give you a good certification right because that also kind of has to trust right so that there are different certification levels i don't have a name on me off and if somebody looks that up remind me oh but you can get your system process software verified at different levels of assurance and these costs increasingly amounts of money not only to get the certification but to actually develop software that is assured to that level yeah so you could try to do that but that's still kind of you know it's a rough one so somebody says you know how much do you trust that this system is correct you said well i have certification level 10 does that really answer their question of how much do you trust it you know like kind of like a product how do you expect average users to be able to validate the security of your software so why is it difficult or is it it's difficult because any number you can come up with you need something different to perform you know you can you can hang up the sign on your webpage and it says 65 days a thousand intrusion that is a pretty good way of quantifying it but people might not care you know quantifying trust is kind of a bogus thing because the reason you have security is you want people to use your system correct yeah so this is actually a really tricky and difficult problem for all of those reasons that you mentioned so it's easy to come up with metrics you can come up with metrics but it's difficult to justify that those metrics actually gets the heart of what it means for your system or software to be secure right or your website to be secure as to why people want to quantify it so from a business perspective bless you from a business perspective if you're the CEO and your information security officer comes to you and says hey i need another you know million dollars in my budget and they go okay well so you know what are you going to do with that money how are you going to either reduce risk or increase our insurance that there won't be any you know issues and how much can you do that by well i think it's safe no they definitely make it better like i won't make it worse it's hard to kind of talk about those issues about the cow you know to actually quantify that and there's a lot of unknowns here right there's a lot of potential vulnerabilities and things you haven't even thought of one of your devs stood up a development server on your network you're not even aware of that's open on the internet and then that allows somebody to come in to literally bypass all the policies and mechanisms that you had in place yes it's a very difficult problem yeah yes that's an incredibly important and why why um why is how people feel about security and being safe important and impact things they can feel safe why would you have to use security like yeah so you have an anti-virus right why would you be careful about what size you visit right it's like the whole george carlin joked that everybody would be really good drivers if they're just a big spike on the uh scare trail right because there's a very clear danger that would happen if you cause an accident right but and i think i believe they've done studies that are shown that as people as cars get safer and they have seatbelts airbags all that kind of stuff people's average speed increases um because they feel more you know doesn't feel dangerous right even though that may or may not be the case so yeah that's that's a good point and we also you know and these mechanisms that we have many are technical but some are people right and so how do you quantify the people component there that they're going to actually follow your mechanisms that you've put in place so it's a very it's actually a huge if you can solve this problem there will be um trucks full of money that will just come to your house and back up into your driveway i mean this is something that would solve a huge serious problem in the security industry and part of this is because i mean you know security is incredibly new field relatively even compared to computer science and especially compared to other engineering disciplines so um you know practice not that'd be good um so we talked about what it depends on right so it depends on you know how much trust we have in the people how much trust we have on the systems it has how much trust we have in our policies our mechanisms um all of these different aspects right these all feed into the assurance that we have of this system cool so now we're gonna get into kind of system development we'll check a little bit closer and kind of go more software based but i'd like to figure about this so what's the specification nobody's ever seen a spec before just go whatever the heck you feel like it's a requirement that has to be met or is is met by the it depends like are we looking at specification when you're designing something or like when to purchase something it has specifications good so we'll talk about system building so we're gonna build some system right we have some specification which tells us essentially what is the system supposed to do right so you know this may or may not be explicitly defined but there is i mean if you're building anything right it's for a specific it's supposed to do something i guess you could create an art project we're just building stuff to build stuff that's not really what we're talking about here so how do you define specifications this is more of dabbling into software engineering and create use cases that's what you can describe okay uh at very high level these are kind of scenarios user scenarios you can define different types of users and kind of what they want out of the system but also with some other ways slightly more low level but you can define kind of what the outputs are supposed to be what you're expecting to get as results of using it yeah so you could define uh if you have a GUI you can find the interface with the interface look like what the inputs are you can define what the outputs are like um you can also define this you know in English a written document that actually specifies these are the specifications of the system do they still teach you um l diagrams nobody thought just all immediately because uh i guess that's not a specification so so we say okay this is what something's supposed to do then what are we doing next do we build it we model how it'll do it yeah we want to think about how we want to build it right so we want to design it so we want to say kind of modeling how we want to do it this does go into the um l so i'll put that there first um so we can define um l diagrams that kind of finds a more granular granular level how the system is going to work but what's the ultimate goal here make money to make money and how do we make money pleasing your customers so how do you know if your customers if you've built something that your customers want by making they're using it so what was back i mean you can put that essentially in your specification right so your specification should capture something that the user wants and will pay for right so that is the ultimate goal of all these steps right so how do we how do we know that the design actually satisfies the specification you're that person you were just hired how do we validate designs can you unit an integration test of design correct we're talking about the design you could do that so you could model it with some modeling program not like a CAD modeling thing but um and you could try to prove it correct against some properties that would be interesting i think those people would work on that because our specification came from requirements and the requirements were gathered from our stakeholders and what the stakeholders once is always changing so if you're designing for what your user wants there's no way to design like to verify yes we have the perfect abstract design what the customer wants we just need to hire someone to code it you can't verify what they want to change so it's just an abstraction of the quality assurance like is the code correct it's an abstraction of that same problem it's a different level right but if you could so would you agree that you could design something correctly that doesn't actually follow what the user wants and then you could build that out 100 correct that passes 100 percent of your unit case unit test spaces and integration test spaces but ultimately never actually solves the user's problem you can have a crappy design that still works just take 10 years to run i'd say that's a fault that would be bad design i mean yeah that would be a problem so the specification should have some notion of this right of time requirements right these are all different aspects of it so we we want to ensure that the design actually satisfies the specification right we're going to get into the security aspects here because they're all intermingled so can we prove it can we prove that this design correctly specifies satisfies the specification oh we can try to build a quick little easy silly thing that didn't seem kind of a good way yeah uh Susan thanks so much for thinking about so when we get to the implementation so then we have to actually implement something right so implementing using code using something maybe in the future we'll be able to just translate the design down to code but i have my reservations on that so the question is does the implementation satisfy the design and furthermore does the design satisfy the requirements right so it's also tied we're also checking does the implementation satisfy the requirements so we talked about unit testing integration testing any type of qa testing because if your design is completely screwed up at this stage of the game go back and completely redo it or try to hack it until it works which is going to cause you problems years down the road and probably but if your company's not going to exist in multiple years we don't do that and sometimes you have to can you prove this use p-trements i mean this may be a stretch but isn't it kind of boiled down to uh just like uh computer science we're proving uh undecidability and such like that like if we imagined that we did have a machine that you know taken down to just because i'm just recently 55 but you know halting on all input there's no way that we could verify our machine was equal to that machine so ultimately isn't it unknowable to prove it both ways i think to make the claim that it was as hard as yeah so i don't necessarily know so yeah there's no you know i think that's kind of the point is there's no real way to prove any of these things right there's no you know too mathematically prove at this stage yeah there are people who are working on theorem provers and building systems using theorem provers and so the point here is also about security at all these stages right so just like we said so finding a security problem at the implementation phase right in the design or even the specification maybe specification did not say anything about security here after it's already built is a incredibly expensive to fix and b is likely that the fix is not going to be correct this is come up time and time again so security in a system if you want to have a high assurance system that you are confident that it is secure you need to think about security in the specification right you should define notions here you should define the threats that you're considering in the specification you want to think through all of these things discuss your threats your threat model the assumptions that you're making right you should all be explicit same with the design you can look at the design and think okay does this design satisfy those threat models and those threats what policies and what mechanisms are you going to put into place into our system are those actually designed in properly same thing with the implementation now we actually have something we can test say okay is the policy from the specification actually implemented correctly with the mechanisms and it does not just stop here a huge thing with security is not only about is the code itself correct because a system does not just execute in isolation like we saw all right now we've talked about right systems have how's it deployed is it deployed on a shared hosting server with multiple users when it was designed to be a single user system how is it configured it's in 100 impossible and happens a lot where you design an application to be secure but it's does anybody work at a place like this where you have devs the developers build stuff and then you have ops who goes and deploys things yeah so you have completely separate people involved in that so that ops people may not be aware i mean it's not their fault or anything but the deployment in a configuration happens by ops so it could be the case that they're configuring something in a way that invalidates the entire security of your application so one example of this will let's say be a database that should be only accessible in your local debt in your local network to be configured to allow remote connections right that would be a very bad configuration mistake and also the operation so how is this you know there it could be deployed correctly configured correctly but because of the operations there can be security problems in here too and this gets into so even if let's say you prove that the implementation of something is correct all the way from specification down to design that implementation now how can you prove that it can actually be deployed and configured and operated correctly this is also one of these open hard difficult problems is how to prove or even how to you know improve our assurance or increase our assurance that yes this thing is correct because we have to think about all of these complicated scenarios and this may be so it's important when you're thinking about the security of a system because this may be a part of your policy right to say okay well how you know thinking through not only how is it implemented but how will it be deployed who's going to configure it how will it be configured who's going to operate it who has added access to your system right all of these things are important things that we need to think about close to the end we'll go over this real quick so we find out this a lot so context is incredibly important in security okay why yeah so why waste money securing it's a threat that you're unlikely to see or a threat that you're likely to see that is it impact you has no effect to your organization and the key question is it's incredibly easy as technical people to get so focused on mechanisms and we've got to implement all these cool technical access control lists and all these things but if we're not thinking about the business aspects of is it worth the cost then we've really kind of failed because our overall goal is securing and supporting the organization's mission not to develop cool security things so that