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Aug
4
comment Why do crypto libs use table lookups when they're vulnerable to timing attacks?
@user54609 bitslicing is only efficient for parallelizable modes.
Aug
2
comment Is modular Barrett reduction usable for Ed25519?
The order is still pretty close to a power-of-two, so you can use a variant of the approach described at: What are the computational benefits of primes close to the power of 2?
Jul
31
reviewed Reviewed How AES treat string input to encrypt data and what will happen if the cipher key is less than that expected?
Jul
31
revised How AES treat string input to encrypt data and what will happen if the cipher key is less than that expected?
deleted 14 characters in body; edited tags
Jul
31
comment Point addition in NaCl/libsodium (Curve25519)
It's public domain if you copy it out of NaCl or SUPERCOP.
Jul
28
comment Factorize RSA knowing several N and E
@Antimony While RSA moduli usually have two prime factors, that's not always the case. Using more factors improves the CRT speedup, but you need to be careful that the factors remain big enough so that elliptic curve factorization (whose cost depends on the size of the factors) is more expensive than GNFS (whose cost depends on the size of the modulus).
Jul
27
comment Point addition in NaCl/libsodium (Curve25519)
NaCl isn't an ECC library, it only offers higher level operations like key-exchange and signatures and doesn't have point addition in its public API. You should be able to find an edwards form point addition function in its Ed25519 implementation.
Jul
26
revised Show How to Efficiently Solve the Computational Diffie-Hellman Assumption given an Algorithm that Solves the Square-DH Problem
edited tags
Jul
26
comment Show How to Efficiently Solve the Computational Diffie-Hellman Assumption given an Algorithm that Solves the Square-DH Problem
Related problem: Can we reduce Diffie-Hellman problem to “Discrete-log inversion” problem?
Jul
26
answered Why is the whole initial state used in the final addition of Salsa20 and ChaCha?
Jul
24
revised Why is Rabin encryption equivalent to factoring?
edited tags
Jul
22
comment Question about the key in RC4
@lena What's your target hardware? The relative performance of ciphers varies a lot between different CPUs.
Jul
21
awarded  Yearling
Jul
19
comment Why don't use random padding in RSA?
AFAIK what Yehuda described is called RSA KEM. I believe it comes with a pretty strong security proof.
Jul
18
comment How is an epsilon of 1/1000 non-negligible?
1) This question is about what it means for an attacker's advantage to be negligible. Your answer doesn't address that at all. 2) Exploiting a weak PRNG to factor an RSA modulus generated by it isn't related to brute-force. 3) If you're referring to the "many moduli have a prime in common" problem, that was caused by very badly seeded PRNGs outputting identical data of several hundred bits for the first request of random data. This is unrelated to small biases.
Jul
18
comment Why does “2xAES-256” provide “99.99%” security strength whereas “1xAES-128” provides “40%”?
@mikeazo Should I trust CipherCloud? has been closed and deleted. While this question isn't as as non constructive, it still has the "I want to criticize that product but must do it disguised as a question" trait.
Jul
18
comment Why does “2xAES-256” provide “99.99%” security strength whereas “1xAES-128” provides “40%”?
I'm closing this because it's not a genuine question about cryptography. It's a post designed to make fun of ridiculous marketing claims, just phrased as a question. If you enjoy debunking bad crypto, you might want to create a blog, similar to Bruce Schneier's doghouse.
Jul
18
comment Deterministic ECDSA signatures?
@DrLecter The OP wants verifiably deterministic signatures and already linked that RFC.
Jul
17
revised Deterministic ECDSA signatures?
edited body
Jul
17
answered Deterministic ECDSA signatures?