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bio website github.com/CodesInChaos
location Frankfurt, Germany
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visits member for 2 years, 9 months
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Jan
22
comment Non-cryptographic hash function as MAC for stream ciphers
Consider universal hashing(such as Poly1305) or SipHash. Are those fast enough for you? If you use Salsa20 from the eStream portfolio, it's standard library NaCl comes with a Salsa20+Poly1305 implementation by default.
Jan
22
comment Modulus for elliptic curve point multiplication
When working in prime fields, you don't need to think in polynomials. You can use simple modular arithmetic.
Jan
21
revised SHA-256 and AES-128
added 1 characters in body
Jan
21
revised Why work in a subgroup QR(n) of an RSA group $Z^*_n$?
edited title
Jan
21
reviewed Approve suggested edit on Modulus for elliptic curve point multiplication
Jan
21
reviewed Approve suggested edit on Why work in a subgroup QR(n) of an RSA group $Z^*_n$?
Jan
21
reviewed Approve suggested edit on ANSI X9.31 standards for generating random numbers
Jan
21
comment How compared encryption algorithm in terms of efficiency
Don't compute, measure. And check out bench.cr.yp.to which lists performance of both DH on different groups and RSA. Though I heard that the RSA implementation they use might be rather slow.
Jan
20
comment Any implication of a Yale result to security of quantum cryptology?
The article is pretty vague but I doubt that it intends to say that you can measure arbitrary qubits in a non destructive manner. It sounds like a highly specific form of measurement that allows you detect certain errors in quantum computing.
Jan
20
comment How can I calculate the time complexity of modular arithmetic?
Do you know the factorization on n? Is n prime? Does n have some kind of special representation (for example it's very close to a power-of-two)? Do you need constant time inversion, or is a a non secret value allowing variable time inversion because you don't care about timing side-channels?
Jan
19
comment How does using salt reduce rainbow table attack?
And creating that rainbow table is more expensive than cracking the password directly. Salts force an attacker to attack each password individually, no more, no less.
Jan
18
comment How to break an arbitrary XOR and Rotation based encryption?
You can describe each output bit as the xor of a fixed set of input/key bits. This results in a few hundred linear equations modulo 2, which can be solved efficiently.
Jan
18
comment What does modular inversion mean?
The wikipedia article is decent: Modular multiplicative inverse
Jan
17
comment Cryptographic Protocol using NaCl
Are you using S' for several clients? If yes, that probably opens you up to replay attacks, since S' can't serve as server chosen nonce.
Jan
17
comment Cryptographic Protocol using NaCl
You probably don't need the nonce, but only because the client short term key already serves as a nonce. And the server short term key serves as a server chosen nonce. If either were used multiple times, that could open up replay attacks.
Jan
17
comment Cryptographic Protocol using NaCl
Your change in notation from CurveCP is a bit annoying.
Jan
11
comment Are there any standards of multi-prime RSA key generation?
Related reading: AGL's blog post about how security and performance scale with the number of primes
Jan
11
revised How to salt PBKDF2, when generating both an AES key and a HMAC key for Encrypt then MAC?
deleted 2 characters in body; edited tags; edited title
Jan
11
revised How to salt PBKDF2, when generating both an AES key and a HMAC key for Encrypt then MAC?
added 213 characters in body
Jan
11
answered How to salt PBKDF2, when generating both an AES key and a HMAC key for Encrypt then MAC?