Why is SHA-1 considered insecure?
<p>Microsoft, google and mozilla have decided not to accept it in 2017 because of the flaws found by researchers. And I saw SHA-1 is depreciated nearly everywhere simply because people think that it's not safe anymore. But unlike MD5, currently there is no known collision found on SHA-1. And even the fastest algorithm for the collision of SHA-1 still requires nearly 2^60 evaluations, which is still a very large number. </p>

<p>My question is why SHA-1, a hash algorithm which hasn't been found any collisions and which still requires a large amount of time to find a collision, is depreciated? I understand SHA-2 is more secure, but it is also slower than SHA-1, why most people recommend to trade performance for the so-called "security" where the security of SHA-1 is not even an issue for most situations?</p>