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Aug
31
comment What are the required security properties for salts?
I would say that given a particular password/algorithm combination, the bit length of salt input should be greater than the equivalent bit length of security requirement, multiplied by the probability of password collision for all users of the algorithm (which is high, say 1.0), multiplied by the lifetime expected invocations of the algorithm (32 billion?) to create new hashes. Therefore if 128-bit security is desired, use 164-bits of salt.. ?.
Aug
28
comment Are there any cryptosystems that use multiple keys to perform encryption instead of one or two?
secret sharing count?
Aug
27
comment Does Curve25519 only provide 112 bit security?
Don't forget that 5 bits of the private key are always the same
Aug
26
comment Does CTR mode yield a PRF?
if the CTR implementation is a black box where the input is the length of the requested output, and the box does not repeat nonces, then it could be considered a PRF up to the distinguishability limit of AES
Aug
26
comment What is stopping someone from saving encrypted info, and decoding it later?
The safeguard is to use Ephemeral key exchange (perfect forward secrecy) and large key sizes that take longer to attack
Aug
24
comment How feasible would it be to generate 300 million public key pairs in 8 hours?
my computer can generate 25 million ECDH pairs (curve25519) in 8 hours using my own code, which is not nearly as fast as it could be, it can easily generate 1 billion key pairs in 8 hours with optimized code, and can do the same for EdDSA pairs
Aug
21
comment Is it possible to generate backdoored DH parameters?
small subgroup attacks on ECDH curves such as NIST P-224 ?
Aug
20
awarded  Enlightened
Aug
20
awarded  Nice Answer
Aug
17
awarded  Yearling
Aug
14
comment How does the HOTP dynamic truncation function generalize to longer hashes?
If you wanted to replicate it, use String[length-1] and do the low 4 bits of SHA-256 or low 5 bits of SHA-512... however the truncation method is probably useless with a well engineered hash function, and fixed LSB or MSB truncation is acceptable.
Aug
13
answered Difference between RSA-617 and RSA-2048
Aug
11
comment Cryptographic random numbers for key generation
@ddddavidee while my implementation is private (with integrated health checks) and designed to interoperate with my other crypto code, the design spec is not, I will post later to sci.crypt under a title starting with "Project Purple"
Aug
11
comment How do we generate AES S-BOX?
Related question crypto.stackexchange.com/questions/18062/…
Aug
10
comment Cryptographic random numbers for key generation
Many cryptographic libraries utilize the operating system RNG, which you may or may not trust, I wrote a wrapper around the OS RNG specifically for key generation, under the assumption that it is possible to compromise the OS RNG to generate poor entropy or predictable values
Aug
7
comment Plain cascade and Xor cascade
I like (and use) XEX type modes, which is essentially $C=E_{K_2}(E_{K_1}(Ctr)\oplus P)\oplus E_{K_{1\ or\ 3}}(Ctr)$
Aug
7
comment Mathematical formula for switching the key for OTP?
The mathematical formula you are looking for is the one that converts random entropy into cryptographically secure bits
Aug
4
comment Authentication using AES
Does the accelerator give you direct access to the round function?
Aug
1
comment Encryption algorithms larger than 256 Bit for “big data” encryption?
I think the actual issue is more with the blocksize of the cipher and not the key size
Jul
31
comment How AES treat string input to encrypt data and what will happen if the cipher key is less than that expected?
The word you are looking for is "Padding"