3 ms·
Typical NIH syndrome. They hired some smart people who are not cryptographic experts and now their cryptography is broken. Which is pretty much the story for a
by fleitz 13y ago
Typical NIH syndrome.
They hired some smart people who are not cryptographic experts and now their cryptography is broken. Which is pretty much the story for anyone who has ever created a custom cryptographic system (and the story of SSL for the first few years).
- trycatch 13y agoRead the comments under TFA. Nothing was broken. The author was quick to write the article without understanding protocol first.
- fleitz 13y agoAnalysis looks sound to me, using msg content to derive the key is generally bad form, especially messages are known to attackers and sent repeatedly. (eg. Hi) It looks like a bunch of convoluted code that doesn't actually accomplish anything. Why is sha1_a = SHA1 (msg_key + substr (auth_key, x, 32)); sha1_b = SHA1 (substr (auth_key, 32+x, 16) + msg_key + substr (auth_key, 48+x, 16)); sha1_с = SHA1 (substr (auth_key, 64+x, 32) + msg_key); sha1_d = SHA1 (msg_key + substr (auth_key, 96+x, 32)); aes_key = substr (sha1_a, 0, 8) + substr (sha1_b, 8, 12) + substr (sha1_c, 4, 12); aes_iv = substr (sha1_a, 8, 12) + substr (sha1_b, 0, 8) + substr (sha1_c, 16, 4) + substr (sha1_d, 0, 8); better than sha1_a = SHA1 (msg_key + auth_key); sha1_b = SHA1 (sha1_a); sha1_с = SHA1 (sha1_b); sha1_d = SHA1 (sha1_C); aes_key = SHA1(sha1_a+sha1_b+sha1_c); aes_iv = SHA1(aes_key+sha1_d); and more importantly why is it better than aes_key = RANDOM aes_iv = RANDOM Are there special properties of the random bits of parts of various hashes that makes it more 'random'? To me it looks like repeatedly sending the same message, or a message whose hash varied by a few bits, would leak part of the auth key, basically the person probably doesn't know what they are doing and are just adding extra 'stuff' to assure themselves it's secure.
- h0cked 13y agoThe comments from TFA doesn't say a shit but full of "you are wrong, because you don't understand it" without debating the technical details.