10,073 reputation
12451
bio website github.com/CodesInChaos
location Frankfurt, Germany
age
visits member for 3 years, 4 months
seen 5 hours ago

Apr
27
comment Secure encrypt-then-sign with RSA
I prefer sign then authenticated encrypt. The only tricky part is including enough information in the signed part - it needs to be able to stand for itself.
Apr
27
comment implementing long term archive encryption
There is no asymmetric encryption/keyexchange that I'd trust for 30 years.
Apr
26
comment How can a key pair be derived from an arbitrary hash?
Factorization only applies to RSA, not to ECC. For ECDSA a private key is just a number in a certain range. Numbers outside of that range can be mapped into the range with the modulo operator.
Apr
25
comment Password verification
Don't read more than the natural size from PBKDF2. Since Rfc2898DeriveBytes uses SHA-1, reading more than 20 bytes is a bad idea. It halves your KDF performance, without hindering the attacker. For client side password hashing I'd also crank up the iterations a bit to 100k or even higher. If that makes it too slow, replace .net's implementation with a fast implementation. Or switch to scrypt.
Apr
25
reviewed Edit suggested edit on Combining AEAD with RSA
Apr
25
revised Combining AEAD with RSA
corrected the link
Apr
24
comment Using the output of a stream cipher, how to guarantee the integrity of 4 bytes of data?
"Concretely use the stream as a key for SipHash" what do you want to say with that?
Apr
23
comment Using the output of a stream cipher, how to guarantee the integrity of 4 bytes of data?
Are you sure that the overhead actually matters? You could also use a MAC with small constant overhead, such as SipHash.
Apr
23
comment Using the same secret key for encryption and authentication in a Encrypt-then-MAC scheme
I recommend HKDF as the KDF when you want to derive multiple keys (for example encryption and MAC) from a single high-entropy master key(not a password).
Apr
22
awarded  Guru
Apr
22
revised How is CipherCloud doing homomorphic encryption?
added 970 characters in body
Apr
22
comment How is CipherCloud doing homomorphic encryption?
@adrenalion The letter, has two parts. One part is the DMCA notice for the images. The other (non DMCA part) is about the false, misleading and defaming statements.
Apr
22
reviewed Approve suggested edit on How is CipherCloud doing homomorphic encryption?
Apr
21
awarded  Mortarboard
Apr
21
awarded  Good Answer
Apr
21
revised How is CipherCloud doing homomorphic encryption?
added 213 characters in body
Apr
21
revised How is CipherCloud doing homomorphic encryption?
added 1788 characters in body
Apr
21
revised How is CipherCloud doing homomorphic encryption?
added 10 characters in body
Apr
21
revised How is CipherCloud doing homomorphic encryption?
added 378 characters in body
Apr
21
revised How is CipherCloud doing homomorphic encryption?
added 6409 characters in body