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Feb
19
comment Full Domain hash library
You can always chain a hash function with a stream cipher. Or simply use the hash in CTR mode for the expansion, similar to what Skein does internally.
Feb
19
revised What is the period of a cipher?
added 6 characters in body
Feb
19
revised What are the computational benefits of primes close to the power of 2?
added 284 characters in body
Feb
19
answered What are the computational benefits of primes close to the power of 2?
Feb
19
revised Can I jettison MAC if I already have SHA1(M)?
added 322 characters in body
Feb
19
revised Idea for secure password hash-likes, is this feasible/usable/workable?
deleted 1 character in body
Feb
19
comment How does BLAKE2 ensure that hash(A) != hash(B) when B = A||0 and both A & B have the same number of blocks?
A draft RFC describing BLAKE2.
Feb
19
revised Good enough deterministic PRNG based on hashes
obsolete due to migration
Feb
17
comment Pseudorandom number generators based on hard problems in mathematics
@poncho There's also "The RSA problem is hard and the hash function used to create the padding is a random oracle".
Feb
17
comment Pseudorandom number generators based on hard problems in mathematics
There is Blum-Blum-Shub, which is related to factoring. But the security proof isn't very tight.
Feb
17
comment Anonymous Gravatar Problem
@fgrieu The idea behind gravatar is associating an image with an email address. So it needs long term email addresses to function properly. A couple of years ago I recovered about 20% of email addresses on stackoverflow by guessing. Others have achieved closer to 50% using a GPU hasher, but on a different dataset.
Feb
16
reviewed Reviewed Decryption of message in IBE without random oracle using bilinear pairig reg
Feb
16
revised Decryption of message in IBE without random oracle using bilinear pairig reg
deleted 16 characters in body
Feb
15
comment SHA-512 Length Field - What is it?
Yes, it's the length of the message in bits (without padding).
Feb
15
comment Alternative sources of random numbers
1) You need something secret to seed a CSPRNG. 2) How would you obtain that data? If you download it, and you even trust the source to keep the data secret, you still need enough random data beforehand to initiate a TLS connection. But if you already have a good random seed, why bother with that stuff?
Feb
14
answered Anonymous Gravatar Problem
Feb
14
comment Factoring two RSA modulus with known $|p_1 - p_2| < \ell $
if $p_1=p_2$ you can simply compute the greatest-common-divisor of $N_1$ and $N_2$ to factor them.
Feb
13
comment Which characters to take into account when calculating unicity distance?
You can get much lower if you use dictionaries containing English words.
Feb
13
comment Malicious DH groups
AFAIK Miller-Rabin rejects non primes with probability of at least 3/4, so after 40 passes even maliciously constructed prime candidates should only pass with probabiility <$2^{-80}$.
Feb
12
comment Java RSA Padding: no libraries used
For signatures you could use full-domain-hash (FDH). For encryption you could use hybrid encryption based on RSA-KEM.