Reputation
10,248
Next tag badge:
77/100 score
15/20 answers
Badges
3 13 46
Newest
 Nice Answer
Impact
~159k people reached

Aug
20
revised Using scrypt to generate key + IV/nonce together
added 146 characters in body
Aug
20
revised Using scrypt to generate key + IV/nonce together
rewrote question, same contents, fixed title
Aug
20
comment Using scrypt to generate key + IV/nonce together
The latter would be mainly an option if a good KBKDF is available in your crypto library.
Aug
20
revised Using scrypt to generate key + IV/nonce together
added 5 characters in body
Aug
20
comment Using scrypt to generate key + IV/nonce together
@SEJPM Yes, but that could be mainly because nobody seems to know about KBKDF's :) It should of course also be possible to do this with a good PBKDF without giving an advantage to an attacker. At least HKDF-expand has been designed for this purpose.
Aug
20
answered Using scrypt to generate key + IV/nonce together
Aug
20
comment Testing PRNG quality from ECC public keys?
Do you have a hint on how the PRNG is bad? Is it also using an ECC calculation, e.g. the Dual-ECC generator? I could imagine that if you can substitute $n_i$ by any algorithm that there are solutions to the equation. On the other hand, if it is just a badly seeded PRNG using a hash, I would hazard that you could not prove that fact (as you can obviously not gain enough knowledge about $n_i$, it is a private key after all.
Aug
20
comment Hashing a Diffie-Hellman result
The result of the key agreement should be put into a KBKDF, rather than being "hashed" (although the difference may be minimal). I'm not sure if ECDH is as vulnerable as ECDSA with regards to leaking the private key if the random number generator fails but maybe this idea could be the base of an answer (I'm talking about the hack by the Chaos Computer Club of the Sony private key here, in case somebody remembers that).
Aug
20
revised Combining several symmetric ciphers using XOR
added 680 characters in body
Aug
20
answered Combining several symmetric ciphers using XOR
Aug
20
comment Possible to detect if a message is PGP encrypted/signed (ciphertext)
Search engine recommendations are however off topic here :)
Aug
20
revised Possible to detect if a message is PGP encrypted/signed (ciphertext)
added 202 characters in body
Aug
20
answered Possible to detect if a message is PGP encrypted/signed (ciphertext)
Aug
19
comment How ECDH algorithm selects modulus value?
@hab In the case of curves over $Fp$ the calculations are performed modulus $p$ and $p$ is part of the domain parameters specified by secp192.
Aug
19
comment Testing PRNG quality from ECC public keys?
Well, the RNG is used to generate the private key and the public key is derived from that if I understood correctly. So if you are worrying about repetition then it will have to be repetition for at least the size of the private key. In that case you would get duplicate public keys. So if you find a dupe, then you are sure that the PRNG is bad. Not finding a dupe doesn't mean the PRNG is good though.
Aug
18
comment Prove that H(s) = G(!s) is a CPRNG if G(s) is one
Formatted question. If anybody knows how to best code a binary complement in Tex please edit it in.
Aug
18
revised Prove that H(s) = G(!s) is a CPRNG if G(s) is one
formatting
Aug
18
comment Is calculating HMAC from hashed input a good idea?
@otus Tried to clarify part 2 and added a part about collision resistant hash functions in case this wasn't clear to everybody instead of posting my own answer. Hope you agree, roll back otherwise.
Aug
18
revised Is calculating HMAC from hashed input a good idea?
added 230 characters in body
Aug
18
revised Is it possible to get an RSA encryption key by comparing the unencrypted and encrypted file?
added 219 characters in body