And we're good to go. And Cindy, take it away. You can do all the introductions. All right. Thank you, Lorraine. Happy International Day of the Midwife, 2016. And welcome to the Georgetown Student Cafe. My name is Cindy Harling, and I'm a midwife and faculty at Georgetown University's online nurse midwifery and women's health nurse practitioner education programs. Joining me later will be Jennifer Jagger, also a midwife and faculty at Georgetown University, and the current chair of the American College of Nurse Midwives Political Action Committee. We are so delighted to be broadcasting out to midwives and midwifery students around the globe. 18 midwifery students, in their final terms, are here on campus to share their experiences learning advocacy skills on Capitol Hill in Washington, DC. It was a happy occurrence when we realized that our students on campus time and their visits to federal legislators fell on the International Day of the Midwife. We used the materials prepared by the organizers of this day in our messages to our politicians and their staff. Before we get started, I would like to acknowledge a number of people who brought this event to fruition. The entire midwifery faculty of Georgetown University has been supportive of these visits on Capitol Hill and the Student FAA. This is a slide of some, but not all, of our esteemed faculty. The staff and volunteers of the American College of Nurse Midwives have helped with the scheduling of the visits and preparing our students to discuss currently supported federal legislation of interest to midwives here in America. And the organizers of this event are to be commended for their hard work, in particular, Seal Jevitt of Yale's Midwifery Education Program, and Lorraine Mockford, our tech support for this session from Nova Scotia. They both have been very helpful, and we thank you. Whether you are a fan of the fictional television shows Scandal or House of Cards, or if you've been following the circus show that is the American presidential election process, we know that politics and policy are important to the health of women and their families. Midwives can make a difference in the health policy arena for midwifery and women's health by advocating for legislation that promotes social justice and the common good. Political participation is addressed, but not a focus in basic midwifery education as students and faculty are prioritizing the acquisition and application of the foundational midwifery knowledge and skills to become safe beginning midwives. However, once new graduates step out into practice, they begin to realize the importance of legislation and regulation on the ability to practice to the full extent of their training and expertise. This importance is usually experienced as legislative barriers to practice. New midwives need to have beginning skills and political advocacy in addition to beginning skills in midwifery care in order to make significant positive change. Georgetown University, with its geographic location in Washington, DC, and its history of proactive engagement in federal relations in the United States, is ideally situated to provide powerful experiential learning for their midwifery students. Today, our students scheduled visits with their United States senators and representatives on Capitol Hill. As Congress is in recess this week, we met mainly with legislative aides and interns involved in healthcare. We anticipated that students would learn about the latest legislative initiatives of interest to midwifery and women's health at the national level, gain experience in communicating the value of midwifery and its contributions to women's health, to legislators and other stakeholders, and appreciate the influence of law and policy on midwifery practice and healthcare system. We hope going forward that these students who have had such powerful learning experiences in political advocacy will be more likely to engage in the health policy arena. I'm now going to turn the microphone over to the various students who will share their experiences and answer any questions that you have. Thank you. Hello, my name is Nicole Mortensen. And I'm Breanne Hudson. We are from Stafford and Phoenix, Arizona. The Grand Canyon and Suara Cactus are in Arizona and we are located in the Southwestern United States. There are 190 midwives that are licensed in Arizona currently. Midwives attend nearly 6% of all vaginal births in the state. This is better than many other states, but we have a long way to go to ensure the ideal of a midwife for every woman. Arizona is considered an independent practice state, meaning we do not have to have supervision by a physician. Today we visited Republican Senator Jeff Flake's office and met with a representative for Republican Senator John McCain. And I met with Senator or the senior legislative assistant for Republican Congressman Paul Gosar. And during the meetings today, I learned how enthusiastic these representative assistants are and how much midwifery really makes an impact across the world. We heard personal stories about how midwifery had involved people in their family and their friends. And it's great that we were able to talk to them one-on-one and really impact their thoughts about midwifery in the United States. And I met with the chief of staff for Democratic Congresswoman Ann Kirkpatrick, who is pregnant and due to give birth in June, and Shera Burke will be attended by some local Washington DC midwives. And both the chief of staff and Ann are both their friends of midwives. They understand the importance of midwives. Where I live in Arizona is very rural. We're a two-hour car drive from any sort of metropolitan area, as is most of the area that Congresswoman Ann Kirkpatrick is over. And so they understand the importance of getting midwives out to the people where they're at. And we talked about some legislation that can support that. So happy International Day of the Midwife. Goodbye, thank you. Hi, my name is Kate Washburn. I'm from Fairfield, Ohio, the heart of it all in the Midwestern part of the United States. Ohio has produced more U.S. presidents than any other state, but unfortunately it doesn't look like we'll be producing one this year. There are 359 midwives licensed to practice in Ohio, and midwives do about 6.8% of the birth. I visited Congressman Mike Turner, Senator Shera Brown, and Senator Rob Courtman's offices. It was really empowering to go out and educate as to what midwives are. Two of the aides had no idea. One said, like, I think I have a partner who's a midwife, but I don't really know what she does. So it was great to educate and ask for support. I felt like the reaction was positive. The aides were engaged, they were supportive, and overall it was a fun, rewarding, and educational experience. So I see myself continuing to stay active in the promotion of midwifery and legislation to allow midwives to practice the full extent of our education and training. Happy International Day of the Midwife. Hello, my name is Heidi Crookshank, and I am pursuing my midwifery education in Seattle, Washington in the Pacific Northwest of the United States. The population of Seattle is 662,400, and the Seattle Public Library items in circulation are 11,744,874. And if that number doesn't knock your socks off, compare it with New York City, population 8.5 million, circulating materials, 6.6 million. So a very educated, curious place to live, and going right along with that, when I spoke with aides and advisors to Senator Murray, Senator Murray, I can't well, and Representative Jim McDermott today, all three of them knew what midwives were, what they could do, and nodded knowingly when I still reiterated what we could do, and had very nice talks with all three office representatives. I thoroughly enjoyed today. I had the special privilege of going to meet with those offices accompanied by Jesse Bushman, who was in a previous slide, and Patrick Cooney, and I really appreciate this opportunity. Thank you very much Georgetown faculty and happy International Day of the Midwife. Hello, my name is Lisa Johnson. I'm from Howell, New Jersey, and in New Jersey we have 299 midwives that was in 2015, and certified nurse midwives have attended 7,437 births in 2013, which is 7.25% of all births, and vaginal births were attended by midwives at 11.69%. Today we met with Senator Bob Menendez of the Republican Party and Senator Corey Booker of the Democratic Party. We met with their staffers, and we had some mixed reviews, mixed experiences with them, mixed levels of education regarding midwives, and mixed reception of midwives, and we really learned the importance of advocacy for women's healthcare legislation, and we are the voice of the women, and it is important for us to spread the education about who we are as midwives, and what we do, and we, going forward, definitely are looking forward to getting more involved in the legislative process, and really moving forward with improving healthcare for women and improving outcomes with legislation in the future. And my name is Lori Knoth. I went along with Lisa, who you just heard speaking to talk to the senators and a congressman of the state of New Jersey, where I also live. I was in Hoboken, New Jersey, which is outside of the New York City metro area. So it's a really interesting patient population with really individual needs, considering the region and the diversity and just women's healthcare needs in general being for women. Like Lisa said, we had a really interesting day on the Hill, but I think the most important thing to think about when you're advocating for women's health or for midwifery is that the most important thing is just to show up. So just to be there, just to show yourself, just to be visible, no matter what country you're in or no matter what city you live in, what kind of town you live in, or the types of limitations or challenges that you face as a midwife, just showing up, but letting people know about that is important. And most importantly, and what we found today was that people didn't really care how much you know until they know how much you care. So if you go in there with something that you're passionate about, whether it's a bill that's being passed in legislature that could really pave the way for other midwives, or if it's some kind of social constraint that you have in the community that you're in that would possibly interfere with the delivery of healthcare to women or your own provider care, I think that it's important to know what those things are and just to identify the problems that you have and to go out in front of somebody and that can make a change, whether it's a congressperson or a senator or some kind of a community leader and just get it out there because that's where change begins. And so if there's enough people like there is on a day like today for the international day of the midwife, many voices speak together and they're all speaking for the women that do not have voices. And that is what midwifery is all about. So even if you're not experienced in politics, if you don't know how a bill is passed, it doesn't matter if you love midwifery and if you think that women deserve that, then there's something that you can do and it's just a matter of showing up. So happy international day of the midwife from us here at Georgetown and get out there and make a change. You're already doing it with every one of your patients. So keep it up. Hi, my name is Stacy Sheeran and I am also representative of the student body at Georgetown North-Smidwives. And I come from the state of Virginia where we have currently as of 2015, 263 certified nurse midwives. Within that we have 736 of those, 7376 of those attended births by certified nurse midwives. The percentage of all births attended by sort of by nurse midwives in the state of Virginia is 7.22% and the percentage of all vaginal births attended by certified nurse midwives is 10.65%. So with that, our state does need more representation of certified nurse midwives and I am glad to say that I will be one of those to help add to the number in that state. Today I was able to speak with two representatives. So Mark Warner was not available if I spoke with Charlie Arnawitt and then, and he's part of the Senate and then our representative for my district, Randy Forbes was not available so I spoke with Chris Manable. I also had the privilege of speaking with them last year with the ACNM conference when we did lobbying. So it was quite impressive that they did remember seeing me last year and remember some of the points that I mentioned prior. And so when I asked them again, if they remember where the midwife was, it was nice to hear that they still remembered. But it was also important to note that they did kind of forget that we are studied under master's degree prepared and there are some differences that they didn't quite understand and that was nice to be able to educate them on that. They also didn't understand the shortage and they didn't understand what great benefit a midwife is in practice to women, children and their families. So as we know when we care for the women we care for the entire family. So it was important to make sure that they understood that. In addition to we were also able to bring into light the bills that we currently have and play in both the Senate and the House. So they were very impressed to hear that and see what ways they can help to make things better for everyone. My name is Elizabeth Lannick. I'm a student nurse midwife at Georgetown University and I actually live right here in Washington DC. Washington DC is a great place to be a midwife and incredibly independent and supportive practice environment in DC. We do have representation from delegate Eleanor Hans-Morton. Unfortunately she does not have a vote. So I chose to join Stacey to talk about Virginia and what was really wonderful about visiting people and talking about Virginia is the staff members that we were meeting there they represent Virginia but they all live in Washington DC. So when I was able to tell them that midwives practice right here in Washington DC there are 33 certified midwives in DC and 10.7% of births in DC are attended by CNN. It really kind of drove the point home that the hospitals that are right there in their neighborhoods have practice in CNN and their family, their friends, their neighbors are having births attended by certified nurse in the Y. So I really want to talk to them about that and also just to learn more about the future of Virginia. Hi, this is Katie. I am also in DC but decided to join along with Stacey in the Virginia meetings. Just to echo what they said already I was really impressed with how much more interest they seem to have this year from the meeting that Stacey had last year. Stacey said in one of her meetings last year she was in a hallway for five minutes this year we got to sit in the representative's office and spent over 20 minutes and he was engaging us in a lot of questions, clarifications and just where the future of midwifery is. I think there's a lot of focus on this now as people are really looking to birth choice. So I'm happy to be a part of this community and happy to be here celebrating International Day of the Midwife. Hello, my name is Ashley Honesby-Clark and I'm from Sulphur, Louisiana, home of Mardi Gras and currently in my state there are 52 licensed midwives to practice and as of 2013 there were 2.62% of midwives that attended all births and 4.27 that attended vaginal births. I visited with David Vitter's healthcare advisor, Taylor and also with Bill Caspi's advisor, Genevieve and what I found was they were very receptive to the information that we were there to present. I went into this very naive and not knowing very much about the legislative process and I still do not know very much at all about the legislative process. But what I do know is that our presence here on the Hill today was important, it was necessary and whatever, even if my senators do not come on board with the bills, I planted a seed. So that next go round, when the next cohort comes that seed can blossom a little more and a little more and a little more until it's time for them to finally jump on board. And I'm excited about that. I'm excited to go back home to Louisiana which is not a midwifery friendly state. Take what I've learned here, apply it to my state and hopefully Louisiana can start to have better outcomes and we can take care of women with all of these healthcare disparities that come from a very poor area. So I'm very, very, very excited to take what we've done here on the Hill back home and happy international day of the midwife from us over here on the Hill with Georgetown University. Hello, this is Morgan. And this is Marion. And we are talking to you in D.C. but we are from Illinois. I am from Chicago, Illinois. And I'm from Belleville, Illinois which is right across the state line from Missouri. We have 444 midwives in the state of Illinois. We do 8.9% of a birth in the state and we have two birth centers, one in Chicago and then one out in the rural area. And this has taken about 10 years to get a birth center up and running. So it's been brought to you by some wonderful midwives locally in Chicago and they did an incredible job getting that up and running. Today we visited Senator Durbin and spoke to his legislative aide and it was such an encouraging meeting. She reinforced and reaffirmed Senator Durbin's interest in women's health and the midwifery. And he even told us about other bills that he's supporting to increase funding to midwives and title eight. And was very interested in the bill that we talked about today. So that was very exciting to hear that he referred with the work that we are doing. Absolutely. Unfortunately, we didn't get to meet with anybody else on our list from our state who represents the voters in our state but we were able to drop off some information on material and we do hope that it will take the time to read and one of the senators is also our main sponsor of our access to maternity care bills. So hopefully we'll be able to follow up with him and continue to stay involved to make sure that Illinois moms get the best available care from us. So happy International Day of the Midwife. For me too, happy International Day of the Midwife. Okay. Hi, I am Melissa Wilmars. I'm a student nurse midwife at Georgetown University. I am from San Diego, California. Fun fact about my district is that we have ridiculous delicious Mexican foods literally on every single corner as a wonderful place to eat. And in my district, there are approximately 43, there are about 1,028 midwives in the state of California and about 43,000 births that are attended by midwives. The total number of births attended by midwives are just under 9% at 8.72. And I was able to have the honor to visit with my congress, excuse me, my senator, Diane Feinstein. I met with her medical fellow, Dr. Tyler Lorrig. And it was a really wonderful meeting. He had lots of questions about midwives. He didn't even, he honestly didn't even know anything about them. He was very, very interested to learn all about what we do and all the information that we could pass along to Senator Feinstein. So it was a really encouraging meeting. I also had the opportunity to meet with the staffer of congress person, actually my representative, Devin Munoz. I met with his assistant, her name is Ruth Hasdavak. She was super awesome. She had a lot of questions as well and she was very interested in passing along the information to Mr. Munoz about midwives in California. And it was really awesome to speak with her most specifically because she is from, literally from right down the road from my hometown. And so she knows and understands that we have a lot, a lack of midwives in my area. So it was really awesome to talk to her. And I was really nervous starting out lobbying but it actually turned out to be really, really fun. And I really hope I have an opportunity to do it again. And yeah, so I hope you guys have a great day and have the International Day of the Midwives. My name is Amanda Willey and this is Casio Deore, right? We are both from Maryland. And an interesting fact about our state is the state court is gel stuck. So there are 290 midwives licensed to practice in our state and midwives do 15% of all the vaginal births in the state. They have performed almost 7,000 births actually in the year 2013, our most recent data is from that year. Today, myself, Amanda and Tally and Allie who will speak next visited representatives Van Hollen and Harris and Senators McCalkey and McCartan. I was really impressed with how today went and how the staff members were to meeting with us. We had one staff member whose wife is due on Monday and was telling us how a face to her his wife is. So we were able to sort of speak on a midwife level and that was very encouraging especially because the senator has been resistant to midwife support of girls in the past. So to have a staff member whose wife was going to be delivered by a midwife was very encouraging and he's going to definitely speak to the senator on our behalf. So and one of the other senators that we met with was really able to relate to the lack of access of care especially with primary and maternity care providers that we are with the bill that we're talking about. His county has no hospitals and no maternity providers or OBs or midwives. So he was really interested to hear about he was really interested to hear about some of the bills that we were discussing and excited for more information. So it really was a great, a great learning experience. Hi, I'm Tally. I was also with Katya and Amanda and me. I had a great experience in representatives of the Young Holland office. We spoke with a young woman who was a staffer. I know Clint East probably and she knew nothing about midwifery so it was really cool to educate her on that and she was just so interested. We actually spent a long time chatting with her about what midwives do and then at the end of the meeting she said, I just can't wait to have a midwife. So it was a pretty cool experience and we got to talk about those bills with her and she was very excited to chat with the representative about that. So it was a pretty cool experience. Yep, and I'm Allie and I'll just kind of read on everything that everyone said already but it was just an amazing experience to share what we've been learning about this entire program and share our excitement and it was really awesome to see how excited the people that we spoke with responded to us and not many only knew about midwives and now they all seem to be much more educated and much more excited to share what we told them today and hopefully this makes a big impact on what they relay to the congressmen and the representatives that they work for. I think that's all I have. Thank you and happy International Day of the Middle. Hi, my name is Jennifer Jacker and I am faculty at Georgetown University. I wanted to thank all of the students for both their full engagement and enthusiasm in today's most amazing opportunity. The students, some of them were nervous, all of them were excited and all of them just represented the profession of midwifery both here in the United States and around the world very well. So a huge virtual applause please for the students and they're just absolutely awesome participation. Happy International Day of the midwife to everyone who is listening, tuning in. I want to also echo the sincere thanks expressed by Dr. Farley to the virtual day of the midwife organizers as well as the Georgetown University and faculty and staff who were instrumental in putting this effort together. To the American College of Nurse Midwives Volunteers as well as staff for coordinating this effort and participation in the day of and again for just these awesome students for their energy and commitment to the profession both clinically and also professionally advocating for legislation and policy that can make our job easier and in turn make the care of women and babies improve outcomes and make our communities healthier. So it's comes full circle. In closing, I'd like to highlight a few things that the students remarked on. It is in addition to being faculty at Georgetown University, I'm also the chair of a committee with the American College of Nurse Midwives who focus on political activities and on advocacy and government affairs work. So I believe fully, it is so important that midwives engage and advocate for changes in health policy legislation and regulation in their hospitals, in their cities, in their counties, in their states. At the federal level, which is what we all did today and also around the world, many midwives engaged in global efforts and the challenges to provide high quality care to women and babies around the world is great. But we have to start here at home too because we could do a lot of things better. And we have the hands and the skills and the love and the dedication, but there are a lot of barriers to practice that we need to get fixes for. And if we aren't going to policy makers, if we aren't engaging in dialogue about how to make change and what change needs to happen, it just won't get easier to care for women and babies the way that they deserve to be cared for. The healthcare system here in the United States is not perfect and we can't make great big leaps in changes all at the same time, but we are trying to make incremental changes that will benefit the patients that we care for. Specifically, there were three pieces of legislation, three bills that we were discussing with federal legislators today. The students and faculty brought the Quality Care for Moms and Babies Act, which is a bill that would improve maternity care for women and families. It's Senate Bill 466 as well as a House Bill, Companion Bill 4695. And students were talking with their legislators today about quality measures and how if we pay for outcomes, good outcomes that midwives typically provide, we're really known for our high quality outcomes. Instead of for procedures that maybe don't have as high outcomes, then we, this is a way to improve maternity care. So really looking at what are quality measures, identifying areas, opportunities for improvement and seeing with changes in policy how that can improve. Also, another bill that we looked at was improving access to maternity care Act of 2015, which is a HRSA, the Health Resources Services Administration Bill that looks at designated areas around the country that don't have adequate maternity care providers. Right now HRSA looks at shortages in terms of primary care providers and this bill would help identify areas around the country where we need more maternity care providers and pay more attention to the sometimes rural, sometimes urban areas where midwives and OBs are needed in order to help the communities be healthy. There was also an education piece that we were talking with some senators and legislators, representatives and their staff about it's a piece that looks at how can we improve access for students to more preceptor sites and that's a reimbursement for teaching both midwives here in the United States that are teaching residents and medical students as well as midwifery students, how do we incentivize the growing of our young and helping to bring more midwives and other maternity care providers into the workforce. So all really important issues, specific federal legislation that can help with the maternity care problems that we have in the United States. There are issues at the state level and again at local levels and global levels but that was our focus for today. The students all have now the responsibility of following up with their state leaders, midwifery state leaders as well as leaders at the national level reporting to midwives in their state about the conversations that they've had with their representatives and also encouraging other students and other midwives to engage and to advocate for changes that will help us care for women and babies in a more efficient and more effective way. We can make a difference not just at the bedside but in terms of systems change and it takes days like this and everyone coming together and supporting each other to make that happen. So again just a tremendous applause pat on the back, job well done to the students and the faculty and thank you to the organizers of the International Day of the Midwifery and this opportunity for students to cafe about their experiences. Are there any questions from anyone in the audience? Feel free to type your questions in chat or to open your microphone and ask a question there but identify yourself if you do grab the mic. Well here's one and maybe I'll just throw it out to the entire room. If you had an opportunity to speak to your legislators what would you say to them about midwifery and midwifery? Hi Lorraine, this is Cindy. Hi Lorraine. Go right ahead. It looks like we don't have many questions so my message to the global viewing audience is to get involved in politics and policy whatever that looks like in your own country and to support midwifery do that in groups. I think it's much more helpful and user friendly to teach our students to value this activity is also important. And it looks like we're gonna end early so thank you so much Lorraine. You've been a great help and happy International Day of the Midwifery to everyone around the world. And happy International Day of the Midwifery to you as well. How wonderful to hear these wonderful students have been doing it. What a terrific opportunity for you. They're all excited too. All right, we're gonna sign off Lorraine. Thank you for your help. Okay, thank you very much. And if people wanna stay around and chat that'd be lovely but I am going to close the recording now.


I'm going to talk about the crypt analysis of print cipher. It's a new kind of attack which we call the inward and subspace attack, and I'll hope to explain why. So this is joint work with Mohammed, Huda and Eric, and we're all from DTU in Denmark. So this is an outline of the talk. I'm first going to introduce, briefly explain what this print cipher is, then explain the attack, and then also outline some relations to other types of attack. In this case, to truncate the differential attack. So this inward and subspace attack implies a strange behavior of print cipher to some more standard attacks. And then at the end, conclude. So print cipher is a lightweight SPN block cipher which was proposed at chess last year, and the idea is to take advantage of a, not of a key, of a fixed key, so the fixed is missing there. Otherwise, it's not very innovative, maybe. And it's also in the chess paper, it was shown that it seems that the print cipher is resistant against the standard attacks, like mainly linear and differential attacks. And so far, there have been attacks on reduced round versions of the cipher. So this is how print cipher, one round of print cipher 48 looks like. There are two versions, print cipher 48 and print cipher 96, but I'm going to focus on print cipher 48 only in the talk. So it's a 48-bit block cipher with 48 rounds and an 80-bit key. And the point is that the main point is that this 80-bit key is the same in each round. So the round functions are identical, including the key up to a round constant. So what happens is that first the state is, where's this laser pointer? So first, the state is exored with a 48-bit exo key. Then the bits are permuted, the 48 bits are permuted according to this present-like permutation. And then six bits are exored with a round constant, which is different for each round, of course. And then to get some more, to get more than, to enlarge the key space to more than 48 bits, some more parts of the cipher have to be key-dependent. And for print cipher, what it's done is that before three bits enter this three-bit S-box, S here, each three bits are permuted in a key-dependent way. And so there are in total six permutations of three bits, but only four are allowed for print cipher. So this is how print cipher works, and this is repeated for 48 rounds. So in the talk, but not in the paper, I'm going to focus on a more simple version, a simplified version of the cipher. It has to make things more clear. So it's not block size of 48 bit, but 24. I am going to fix the permutation key to make things easier, and I'm going to modify the S-box. So it's a completely different algorithm I'm going to show you. But the point is that the kind of the attack takes over to the original. The ideas of the attack take over to the original cipher. So I start with explaining what this modified S-box is. So the modified S-box is a property that it has many fixed points. So S of 0, 0, 0 gets mapped to 0, 0, 0. S of 0, 0, 1 is 0, 0, 1. S of 0, 1, 0 is 0, 1, 0. And S of 1, 0, 0 is 1, 0, 0. And the point is that this can be, it's convenient to rewrite this in the following way, saying that S of 0, 0 star, where star is arbitrary, as a 0, 1 gets mapped to 0, 0 star. And similar things for the other bit positions. And the important remark is that the original S-box fulfills something which is very similar to this. Okay, so this is a picture of the simplified version. 24 bits. First thing is XOR with a 24-bit key. So then there is a permutation which is also very similar to the permutation of the original print cipher 48. And then there is again a round constant, as in the original cipher. And then instead of these red key-dependent P permutations, I now fix one permutation. And then you have this modified S-box applied. And then you repeat this. So how does the attack work? So the first observation is that we're going to look at these 8 bits. So I highlighted 8 bits in this linear part there. And the point is that those 8 bits get mapped to the same set of 8 bits by the linear layer. So this is kind of, if you want, an invariant subspace for the linear layer of the cipher. So this alone is certainly not a problem. For most of the ciphers, I guess you would find the invariant subspaces for the linear part of an SP network. So the main question is how does this relate to... So what happens with this invariant subspace when it goes through the S-box layer? And for this, we are going to fix some bits in the plaintext, but also in the XOR key. And because we have to fix some bits in the XOR key to certain values, that already implies that this attack is not going to work for all keys. But it's going to work only for a certain fraction of keys. These will be weak keys, if you want. So this is the simplified version again. And now I'm going to fix these 8 bits to 0 in the plaintext. And I'm also going to fix the same 8 bits, the same position to 0 in the XOR key. So this implies, of course, is that I have those zeros at the inputs to the S-box. And then for all the other bits, I don't really care, so there can be anything in the plaintext. And there can also be anything in the key. And then I get... look at what happens to these. The important remark here is that when it comes to XORing the round constant, here I have only stars. I have only values which I don't really care about. And this is not changed by XORing the round constant. So this is the state before the S-box layer. And now recalling the special property of this modified S-box, saying that 00 star gets mapped to 00 star and so on, means that I can, with probability 1, so far everything happens with probability 1. I get this at the end of one round. So I start by a plaintext where I fix some bits and then after one round I have again some bits fixed to 0. And the main point then is that those things are actually the same. And because they are the same and the round keys are all the same, this property iterates over any number of rounds, basically. So this means if certain key bits are 0, and I fix certain bits in the plaintext to 0, then I get also 0 bits in the ciphertext. So as I said, the round constants do not really help because no bit is fixed where the round constants are XORed and it works for the whole cipher. Something very similar happens for print cipher 48. So here is actually the kind of similar property that holds for the original S-box. So instead of having all things fixed to 0, one has to fix some bits to 0, some bits to 1 in the plaintext and also some bits to 0 and some bits to 1 in the XOR key, but more or less the same thing happens. You again get a one-round iterative property for these weak keys with probability 1. Yes. So it's a probability 1 distinguisher for the whole cipher for the weak keys. Around 2 to the 50, I think it's actually 2 to the 51 of 2 to the 52, but yeah, might be a bit wrong, but around this, 2 to the 50 out of these 2 to the 80 keys a week and something similar happens for print cipher 96. And so to give a bit of an abstraction of this attack, what happens is that you have a round function where you can identify a subspace U and the constant D so that this round function maps this subspace or this coset of the subspace to a coset, to a different coset of the same subspace. And then if the key is such that it's in a certain coset again, it follows that the round function, including a final XOR in this notation here, maps a coset of a certain subspace to itself. And this is exactly what happens for print cipher 48 and this is where the name comes from. It's an invariant subspace. So next thing I would like to talk about is a relation to truncated differential attack. Actually again to simplify things, I'm not going to talk about truncated differentials but only classical differential characteristics. So what we normally see is when we talk about the probabilities of characteristics is that if I have an R-round differential characteristic, now it's a one-round iterative thing so I have a different alpha going to a different alpha and so on, with probability P for one round, then one can show that if you assume independent round keys that the average probability taken the average of all keys is P to the R. So the probabilities multiply along these characteristics. And also what one often assumes is that all keys behave similarly. So for a fixed key, you also get a probability which is very close to P to the R. And as it turns out, this is a print cipher behaves very differently in this respect for some differences, for some differential characteristics. So to explain this a bit easier to make things even more easy, I'm going to consider only a two-round characteristic. So I have a different alpha and it should go to a different alpha and it should go to a different alpha. And I have a round function. I also ignore the whitening keys if you want. So I have a round function R that I apply. I'm going to X or a key in the middle and then apply the same round function again. And then this set A, you can think of this set A as the set of all good pairs. Of all good pairs, fulfilling the one-round characteristic alpha goes to alpha. So if you want to compute the probability for this two-round characteristic, what has to happen is that if you have a good pair here, you apply the round function to the good pair and X or the key, and then this has to be again a good pair. So it means the probability for this two-round characteristic is the size of the set A, a round function applied to A, X or the key, and then the intersection with the set A itself. And then you have to scale by two to the end. So this is the probability for a two-round characteristic for the given key K. So in the picture, this means that you have to look at the intersection of the set A with the set R of A plus K. And for different keys, this intersection can look differently. So what happens now for print cipher is that you can define the difference alpha such that the set of good pairs is actually the set which is invariant under the round function. So that means that A is actually in a fine subspace U plus D and that if you apply the round function to the set, you get U plus C, so a coset of the same subspace. And then if you look at this formula for computing the probability for the two-round characteristic, you get that you have to intersect this coset of the subspace U with this coset, the subspace U. And now this is different because you have two cosets of the same subspace, there are only two possibilities how they intersect. So either the intersection is empty, so they are disjoint, or they are the same. And this means that it kind of already indicates that something strange can happen here. And actually you can show that there exists an R-round differential characteristic such that the probability is either 2 to the minus 16 for any number of rounds or zero. Depending on if the key is weak or not, you either get the probability to the minus 16 if the key is weak or probability zero if the key is not weak. So this is coming back to what I started with in this section. So here probabilities do not multiply, so it's independent of the number of rounds and they are very key dependent. So depending on the key, the probability is very different. So to conclude, so this invariant subspace attack, it identifies weak keys for the full Prince Iphone 48 and Prince Iphone 96. I didn't talk about this, it's in the paper. And I also mentioned this strange behavior for some differential actually truncated characteristics. And there's in the paper, but I don't have time to talk about this. There's a similar observation for linear attacks. And we're also again, Prince Iphone, some linear approximations don't behave as you would expect them to behave. So future work is to generalize the attack. Another open problem is that so far this is only distinguished. So if you have a weak key, you can easily identify that you have one of those 2 to the 50 something keys, but finding the correct one out of these 2 to the 50 is still not, we still don't know how to do this. And another thing which I think is interesting to explain, this strange behavior of the linear attacks directly. I think this would be nice to be able to do this. And that's all I had to say. Thanks. We have plenty of time for questions. Any questions? Yeah, the paper of whom? Okay, I'll have a look. I will ask you a question. Did you look at any other lightweight encryption schemes looking for similar properties? Yes, we were looking for similar things, but I mean this property that this S-Box has, this thing, this one, this is unlikely to happen for larger S-Boxes. So it's really the point that for 3-bit S-Boxes, any strange things might happen. I mean we looked at present a bit as a natural similar thing, but there we couldn't find something. And also, I mean one thing that you kind of need would be nice for the attack at least is to have constant round keys, because then it iterates. So we looked at Nokion as an example, but we tried kind of basic things. So we cannot say that it doesn't apply, but we were not able to apply it. Okay, so let's thank the speaker again.


All right, so I don't know how you feel right now. I know that I've been recording this lecture and prepping for this lecture for what feels like 100 days and I'm ready to get moving. One of the reasons why this video took me so long to prep is because I actually put together a key for our list of required histology for today. And I don't know if this is going to work or not, but what I have is basically all the tissues you have to know down the right hand side of this key. And my intention is that you will be able to use this thing to help you sort of target the significant features of the 20 different tissues that we're going to be looking at. It is not complete, it's not comprehensive, it's sort of windy-ish because look, most of the cells look like pinkish concave donuts lacking nuclei. That doesn't sound super scientific, maybe a little rigged-ified. Yeah, this whole thing has been rigged-ified. And maybe you'll be like, ah, that's not going to work for me. I don't know, we'll try it out. If it does help, let me know. If you are not in my class and you're interested in this thing, I'm going to try to link on the YouTube video, I actually posted it to a Google Sheet that anybody can have access to. So if anybody else wants to try it out, my only condition of you trying it out is that you tell me how it worked for you and what would make it better. So we'll try to do a little research on this thing. But the reason why I'm showing it to you is because I'm not going to go back and forth on this thing. Like I'm really not even going to look at this anymore. I'm going to let you look at it as you're sort of studying and preparing. In fact, probably a great thing for my students. This is in Canvas. Print this thing out as you are watching this lecture or watch the lecture and then print it out. And see if you can identify, see if you can see how it's kind of organized and the things to look for that help you define the tissues and distinguish. You tell me, does the tissue line a space? If it lines a space, like if it's right next to a space, what kind of tissue is it 100% of the time guaranteed? Well, it's going to be some kind of epithelium. So it's going to say, yeah, lines of space, go to number two. Well, number two, we're definitely going to start getting in epithelial tissues. And look, all of these are epithelial tissues. So the strategy is set up to try and help you identify the significant characteristics. What I'm going to do now is show you pictures of these things. I'm going to show you the pictures in the order of the dichotomous key. So while I'm not going to come back to this thing, if you do, you can actually see how I described it on the key and compare that to what you're seeing in the slide, the image that I'm going to show you. Okay? So you tell me which tissue are we going to look at first? The composed tissue. Okay. So this is actually in a histology lab, which over half of our labs have some histology component to them, not all of them, but over half of them. So when we do histology on a quiz or an exam, I usually do the questions like this on a PowerPoint slide. In fact, I stole these from an existing quiz and just basically made it look exactly like your quizzes are going to look. Even down to the question, we have 20 slides to look at right now and every single one of them has the exact same question on it, which is name this tissue. The first tissue that we're going to look at is this tissue with these big open spaces. And I'm going to tell you right now inside those spaces is actually lipid or fat.  These cells store fat. It's a kind of connective tissue. I wish I could write on this thing, but I can't. My technology won't let me do that. So you take notes, take notes. And then your vacuole found inside what kind of tissue? Adipose tissue. So this first tissue, there's six, I think, tissues at the beginning of my key and all six of them are like, dude, these are... Okay, there's five, I mean. These are the easiest tissue. You hope that these are questions on the quiz or exam because they're really, really straightforward and really, really easy to see. Adipose tissue, super straightforward. Looks like a whole bunch of open spaces. Look, donuts. Concave pink donuts. These are red blood cells. This is blood tissue.  White blood cells are larger than red blood cells. The space here is just blood plasma. Obviously, it's a slide, so the plasma's all dried up. It's blood tissue. It's super obvious. If you see it, you're going to be really happy. This one, this might be my favorite slide of all. It's compact bone tissue. It's shockingly cool in these concentric circles of hard tissue. These little dark spaces are actually... They're actually spaces where the bone cell or osteocyte lives. So the osteocyte lives inside that space. One of the characteristics of structural connective tissue is that there are spaces. The spaces are called lacuna, and the space is where the cell lives. So you can't really tell that this is lacuna, but it is. The big central thing in the middle is where blood vessels travel because bones do have bloods and nerves going to the bone. That's why if you break your bone, it hurts. And there's something else I was going to tell you about this. Super obvious. It's really pretty, isn't it? Okay, compact bone. Look at the stripes on this one. This one's really cool, too. This tissue right here, this thing right here, that's one cell. Here's another cell and another cell. And do you notice the stripes? The stripes are the significant piece. This is actually striated skeletal muscle tissue. And each one of these tube things is one cell. You'll notice these, this is possibly a confusing bit. They're actually nuclei, and I don't know if you can tell, but the nuclei are on the edges of the skeletal muscle cell. So this long cell has nuclei squished around the edges, and that's because the rest of the entire cell is full of proteins that enable contraction. Awesome. So if you see something that looks like this, super striated nuclei on the edges, that's going to be skeletal muscle tissue. The last super easy one is our lone ranger. This right here, look at the size of this cell.  But look at that big, huge cell. This is a neuron. This is a neuron cell body. So what kind of tissue is this? This is an example of our neural tissue. There's all different kinds of neural tissue. This is a smear, and this is the, in fact, this is our, one of our slides that I believe I took a picture of. And so this is almost exactly what you will see in lab on whatever day you come to lab. All right, so this one, I wanted you to see the tissue, and I also wanted you to identify the structure indicated by this arrow right here. The structure will help you identify the tissue itself. First of all, what do you notice up here? It's a space. And if this is a space, what kind of tissue do you think this is? Epithelial tissue. And if this is epithelial tissue, what do you think this structure is? Connecting the epithelium to the underlying tissue.  I wish I could draw on it to show it to you. It is, you can see it, like right there, you can actually see the line. It's epithelial tissue. What kind of epithelial tissue is it? Well, my friendlies, how do we decide? If we look down here, you might be like, dude, it looks kind of bubbly. Must be like transitional epithelium. You will be in trouble if you answer that. So, how do we decide on the shape? It's definitely got multiple layers, but this right here, what is the shape of those luminal cells? Those things are definitely flat. This is stratified, squamous epithelium. It's actually found in your eyeball. It's super cool. Who's this? Look, again, what's this right here? Space. What means what's this right here? Basement membrane. Which means, what do you think, stratified or simple? Hopefully, you definitely are like, dude, it's stratified. Except, go look at the luminal layer. What is the shape of those cells? This is transitional. This is actually quintessential, beautiful transitional epithelium. Notice those bubbly luminal cells. They look sort of cuboidal, but they almost don't even look cuboidal. They look balloony, bubbly. Balloony is not a word. Okay, what do you notice up here? Space. What do you notice right here? Sometimes, it's super clean and clear, and other times, you kind of have to know that it's there, here it's nice and clean. What's my basement membrane? Which means, what kind of tissue is this? Connective tissue. Looks like a mess. It's totally connective tissue. What kind of cells do you think these are? What kind of, what's the shape of these cells? This is my basement membrane down here, and here's my lumen. How many layers do we have? One layer, long, tall cells. This is simple columnar epithelium. Notice up at the top, it looks like there's some furriness at the luminal edge of these cells. Maybe cilia, I actually don't know where this is. Oh, it's in the gallbladder. That does not help me. I don't know if there are, I guess there would be cilia in the gallbladder and not microvilli, but there are definitely extensions on the luminal end of the cells. All right, who's this? What's this structure down here? Basement membrane. What's that up there? Space. What do you notice about these cells? What do you notice about the number of nuclei? We definitely don't have a single layer of nuclei, do we? And in fact, like, whoa, there's lots and lots of layers of nuclei. Do you think that this is a stratified tissue? No, this is actually pseudostratified columnar epithelium. And this stuff up at the top, those are cilia. So this is ciliated pseudostratified columnar epithelium, because these are all individual cells. Check out this one. This is actually, nobody cares where it is. The two arrows are sandwiching the tissue. So the tissue is found in between those two arrows. Do you see any spaces? Space. What kind of tissue are we talking about? Epithelium. What's the shape? How many layers do we have? Dude, do you even see one layer? Like, that's a thin layer. If that's a layer, it's a layer. It's one layer. It's a simple, what's the shape? Squamous epithelium. On a quiz, this, in fact, was taken directly from a quiz. On a quiz, I would sandwich the tissue just like this if I was trying to grab the simple squamous epithelium, because it's hard to visualize halfway through. That was pretty easy, wasn't it? What's next? What about these guys? Do you see a space? Totally. Look, this is a tube. This is the lumen of a tube, which means over here on the basal side is my basement membrane, and you can really see it. I almost wish I could zoom in a little bit more on this one, because that basement membrane just sort of pops. Histo's so fun when it pops. This is the shape of my cells. Those are like the best example ever of cuboidal epithelium, simple or stratified. One layer, simple, cuboidal epithelium. How do I know that these aren't all layers? Well, you just get a sense of where the basement membrane is. This is actually like jillions and jillions of tubes. Here's an interesting place. It's a tube that actually got cut the long way, which is how the lumen of the tube looks really, really long, but it's because we cut the tube in the long way, which is why it looks long. Look at this tube. This is a tube as well. It's simple cuboidal epithelium, but do you see a space right there? No, that's because the tube got cut on the edge of the tube, so you didn't catch the lumen in this part of the tube. One of the most challenging things about anatomy in general and histo in particular is you have to visualize the slice. There's this spatial magic that has to happen where you can visualize a tube that gets cut and then or any body part, a brain or whatever, that gets cut and then you have to imagine what that looks like on the cut edge. Okay, simple cuboidal epithelium. All right, we are out of epithelial land. There's a couple of clues here that are interesting. First of all, does it look tidy and organized to you? Honestly, to me this looks like somebody finger painted with pink pudding, which I actually right now at this moment would be kind of fun to do. The pink pudding like smear things, collagen fibers, big, thick collagen fibers. That's hint number one. Hit number two, these big circles. See how huge they are? They're big circle spaces. They're houses for cells. I already told you about one kind of tissue that had a little home for a cell called a lacuna. Remember compact bone? What do you think this stuff is? It isn't bone. This isn't an example of spongy bone. This is actually big, thick collagen fibers. This is fibrocartilage. The space, the big lacuna, the cell inside it, and those giant fibers. That is an example of fibrocartilage. There's nothing that you will mix that up with. You got to see the lacuna in order for it to be structural connective tissue. All right, lacuna are also in this one. Do you see them? The foliage and spongy bone actually look, it's almost like bubbles coming through fluid. Doesn't it kind of look like soda pop or bubbly carbon dioxide, whatever? This is a lacuna. This is where a cell would live. Now, if it has a lacuna with a cell living inside it, what kind of tissue do you think it is? It's going to be a structural connective tissue. And I'll tell you again, it's cartilage. And here's your clue. If you look at this stuff, do you see how it kind of looks spiderwebby? Doesn't that look spiderwebby right there? Those are elastic fibers in this cartilage tissue. What kind of tissue is it? Elastic cartilage. Look for your lacuna. Look for your elastic fibers. Are there collagen fibers in this tissue? Totally, it's connective tissue. All my connective tissues have collagen fibers in them with possibly the exception of blood. I don't know. What was I saying? I was saying something elastic. I can't see the collagen fibers in cartilage. I remembered. Oh my gosh, I'm on number 13 of 20. I'm not counting. Structural connective tissue. What's left? Oh, there are two left of our structural connective tissues. This one, do you see my lacuna? My spaces, look, those are the spaces that are found in the structural connective tissue. So there's cells living inside there. You know what, the shape of this thing, this thing that has lacuna in it, that's your giveaway. This shape is what you see in spongy bone. If you see lacuna in weird island shapes, you're in spongy bone land. It's easy to get spongy bone mixed up with this next one. It's our last structural tissue, but this next one does not get shapes like this. This next one is just regular cartilage and that's called hyaline cartilage. Hyaline cartilage also has collagen fibers, but it's a really clear cartilage. Fibro cartilage had those big, huge collagen fibers that you could see, elastic cartilage had those elastic fibers. Hyaline cartilage almost looks like there are no fibers in there. There are, but you just can't see them. Process of elimination, do you see my lacuna? Look at all those lacuni, they're everywhere. Real cartilage cells or chondrocytes living inside them. Ah, what's that? Looks like a mess. It's connective tissue. Do you see fibers? Look at these fibers. What do you think the big pink fibers are? Collagen fibers. What do you think the little, thin spider web-looking fibers are? Elastic fibers. What do you think the dots are? Fibro blasts. They're blasting out fibers everywhere that they are. They're barfing out all these fibers right here. This tissue looks like a bunch of tinny winks got thrown up in the air with some M&Ms in the mix and ended up with just like pure madness. It's loose connective tissue or a realer connective tissue and it's a type of connective tissue proper. So we are no longer in connective tissue land with all of our structural stuff. We are still in connective tissue land. We are, I'm telling you, these pink lines, what are these things? Connective tissue, big pink things are fibers. What kind of fibers are big and pink? These are giant collagen fibers. They're giant collagen fibers. Do they look like they're organized or unorganized? Well, you might think that's unorganized, but I'll tell you right now. Dude, if my kids' rooms looked that clean and organized, they would have a little party right now, right about now. This is dense, regular connective tissue and these little dots right here, these are your fibroblasts. Dense, regular connective tissue kind of looks like skeletal muscle tissue. No striations and the cells are outside of the fibers. They're not like in muscle tissue, the cells, those circles look like nuclei. They are nuclei in muscle tissue and they're found inside the cells. These cells are all over the place. They're found in between the fibers. They're not actually in the fiber, which means they're not actually in nucleus because they're not, they're cells. All right, does it look dense? Do you see any lacuna? No lacuna, no lacuna for you. Do you see cells? Yeah, holy cells, like these are my fibroblasts. They're definitely blasting some fibers. Where are the fibers? Dude, that pink vomit. Those are collagen fibers. Does it look dense? Does it look regular? This is dense, irregular connective tissue. Okay, look really closely. These are nuclei. Do you see any striations on here? You do because they're there. You kind of have to look really closely, but it's true, they're there. They're striated tissue doggies. These things right here, those are actually the structures. They're called intercalated discs. Certainly not going to test you on them, but those distinctive vertical lines in this mess. It looks like collagen, doesn't it? Flamingo vomit, no. These lines are actually characteristics of cardiac muscle tissue. Cardiac muscle tissue is striated. Cardiac muscle tissue has these connectors between the cells, and they're super significant. We're going to look at all this stuff again. At this stage in the game, all you're doing is going, ah, I see those lines. I see striations. I'm going cardiac muscle tissue. Striations mean it's either skeletal or cardiac. These lines mean it's cardiac. This is our last one. It's so pretty. First of all, okay, this is the tissue. I probably should have thrown an arrow on this one because that's actually, those are neurons cell bodies. That's super cool too, but these, this is what we're looking at right now. What, doesn't it look smooth? Doesn't it look smooth? Look at the shape of the nuclei in this tissue. These are the nuclei of individual cells. This is smooth muscle tissue. And we're going to see lots of smooth muscle tissue in lecture number five when we do digestive histology. So there you have it.  All of that prep work prepped you for your lab. You know what we're going to get to do in lab? Not this. I do not have to talk to you during lab. You get to have your face in a microscope, looking at tissues and practicing, identifying these things. By the end of lab, you will be feeling very comfortable and ready to go. All right, holy cow. I have no idea how long that thing was and I can't figure out how to turn it off. I guess that means I just don't want to go yet. Do you want to keep going? I bet I could think of something else to tell you. Just kidding. All right, see y'all in class. Bye, bye.