Related: in tptacek’s Cryptopals/Matasano security challenge, there are two kinds of problems: A) Implement this off-the-shelf cryptosystem based on the public

Related: in tptacek’s Cryptopals/Matasano security challenge, there are two kinds of problems: A) Implement this off-the-shelf cryptosystem based on the public documentation about it. B) Given this cryptosystem and these hints, find and exploit a vulnerability. Surprisingly, I found the type A problems harder — because the documentation was always missing some critical knowledge you were just supposed to know.