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Sep
6
comment Does it make sense to have a compression function that uses 64-bit of the message to create an output of 64-bit?
As a trivial break, consider the 0 case. What obvious input hashes to 0? If you wanted to generate collisions for 0, how could you force the internal state to reach a value of 0?
Sep
6
comment Does it make sense to have a compression function that uses 64-bit of the message to create an output of 64-bit?
This sounds like a homework assignment. A general hint: Consider how current_block and last are combined - it's simple addition. The next two steps are mixing the state using a reversible operation (assuming << and >> are not cyclical, which they are not in the provided language).
Sep
6
comment Who uses Dual_EC_DRBG?
This is not much, so I'll just leave it as a comment, but a notable founder of a security research/pentesting company recently said that, in his assessment, no one really uses it.
Sep
4
reviewed Edit What is an active S-Box?
Sep
4
revised What is an active S-Box?
Language correction and a bit of logic reformatting.
Sep
4
reviewed Approve What are the advantages of TOTP over HOTP?
Sep
3
reviewed Edit Why the symmetric key layer in PGP?
Sep
3
revised Why the symmetric key layer in PGP?
made urls clickable
Sep
2
revised Initialization vector in symmetric-key encryption
Added relevant tag. Removed unnecessary formatting.
Sep
2
answered Initialization vector in symmetric-key encryption
Aug
31
comment Why is the complexity of RSA-1024 80 bit and not 86 bit?
Somewhat obvious, but worth noting, on the topic of rounding, that all the key strength sizes list are an integral multiple of 8, aka an even byte length. Byte lengths are very convenient for implementations, so it naturally makes sense to use those as notable strength size increments.
Aug
30
revised What is the meaning of “trapdoor” in cryptography?
Added relevant tags.
Aug
30
answered What is the meaning of “trapdoor” in cryptography?
Aug
28
answered Multiple iterations of AES for key derivation?
Aug
28
comment Multiple iterations of AES for key derivation?
The odds of hitting such a cycle with a standard KDF number of iterations, such as 10k, are very low.
Aug
28
comment Why restricting SHA3 to have only two possible capacities?
@AlexandreYamajako: This is about the internal working state size, not the output size.
Aug
26
reviewed Approve Perfect zero knowledge for the Schnorr protocol?
Aug
22
awarded  Yearling
Aug
20
reviewed Approve birthday-attack tag wiki
Aug
20
reviewed Approve merkle-damgaard tag wiki