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I am a math/computer nerd. Nothing to see here, move along.


Oct
9
revised what are the uses of tweaks in block ciphers?
added 36 characters in body
Oct
9
answered what are the uses of tweaks in block ciphers?
Oct
4
answered Difference between salted hash and keyed hashing?
Sep
23
reviewed Close Stream vs Block cipher: Synchronising and the receiver
Sep
16
revised What is the ideal cipher model?
added 1056 characters in body
Sep
16
revised What is the ideal cipher model?
added 1056 characters in body
Sep
15
comment What is the ideal cipher model?
@pg1989 MD5 uses a Merkle–Damgård structure with a Davies-Meyer compression function. The compression function uses a block cipher. A natural question to ask is if we can prove MD5 is, e.g., collision resistant by starting with some assumption about the security of the block cipher. My point was that the PRP assumption won't help us out here, because the PRP definition assumes a random secret key, but the block cipher is being used in a mode of operation where the key bits are known to (in fact, chosen by) the attacker.
Sep
15
comment What is the ideal cipher model?
@RichieFrame It's true that if you use a Davies-Meyer compression function, the message bits get used as key bits in the block cipher. But the message bits certainly aren't secret when talking about collision resistance (and they aren't necessarily random, either).
Sep
15
revised What is the ideal cipher model?
added 83 characters in body
Sep
15
revised What is the ideal cipher model?
deleted 2 characters in body
Sep
15
revised What is the ideal cipher model?
deleted 5 characters in body
Sep
14
answered What is the ideal cipher model?
Sep
6
reviewed Close What are some of the major differences between PyNaCl and PyCrypto?
Sep
5
awarded  Custodian
Sep
5
reviewed No Action Needed Who uses Dual_EC_DRBG?
Sep
5
awarded  Custodian
Sep
5
reviewed Leave Open Why the symmetric key layer in PGP?
Aug
29
answered AES CTR with similar IVs and same key
Aug
24
comment Do ciphertexts leak information about their algorithmic creators?
Minar's point was that a good block cipher is computationally indistinguishable from a random permutation. That is, AES (with a random key) may not be a perfect random permutation, but in practice attackers cannot tell the two apart. This is a design goal for block ciphers that is expected to hold "out-in-the-field"; if someone were to demonstrate that AES lacks this indistinguishability property in practice, they would send cryptographers scrambling for a new block cipher. Most experts believe this is unlikely to happen any time soon.
Aug
15
awarded  Yearling