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bio website github.com/CodesInChaos
location Frankfurt, Germany
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visits member for 3 years, 5 months
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Dec
11
comment RSA or Paillier is good?
I suspect you have a misunderstanding about what homomorphic encryption with RSA or Paillier achieves. Encrypting files like that is almost certainly not useful.
Dec
11
revised 2048-bit RSA Decryption
rolled back to a previous revision
Dec
9
comment Is a strong block cipher usable as a strong sponge function?
What's a bit annoying here is that you need to make relatively strong assumptions about the block cipher, not just that it's a PRP.
Dec
8
awarded  Popular Question
Dec
5
comment Is there (this) a case in which salting is dispensable?
Salting prevents many multi-target attacks, not just rainbow tables.
Dec
5
revised Initialize the eight working variables SHA256
edited tags
Dec
4
revised Will X9.31 remain a secure & acceptable deterministic random generator beyond 2015?
added 9 characters in body
Dec
4
comment SHA1 - SSL/TLS Cipher Suite
@crypto-learner The attacker would get the CA to look the harmless looking one of the colliding pair and then use the malicious one with the same signature.
Dec
4
revised Using machine-learning techniques for data-dependent operations in ciphers
added 2 characters in body
Dec
4
reviewed Edit point decompression on a elliptical curve
Dec
4
revised point decompression on a elliptical curve
improving formatting, typos
Dec
3
comment Is this problem based on a known hard problem?
I have never seen a meaningful reduction to knapsack. There are almost always issues around asymptotic vs concrete security and average vs worst case. I wouldn't not use anything knapsack based in practice.
Dec
3
answered I don't care about replay attacks. What should I do with the nonce in nacl?
Dec
2
comment Repeating something encrypted and non-encrypted?
As long as your encryption is secure know plaintexts don't help the attacker.
Dec
2
comment Does Ed25519 support cryptographic threshold signatures?
There is always the generic solution: A public key is the concatenation of n individual public keys and the threshold m, a signature is the concatenation of m individual signatures.
Dec
2
revised Does Ed25519 support cryptographic threshold signatures?
added 147 characters in body
Dec
1
comment SHA1 - SSL/TLS Cipher Suite
I'm not sure if that Certificate collision attack would still work, even if people managed to do a chosen prefix attack like what happen with MD5. In response to those attacks many (all?) CAs included a piece of unpredictable data early in the certificate, which should prevent collision attacks.
Dec
1
comment SHA1 - SSL/TLS Cipher Suite
@crypto-learner The typical attack based on collisions in certificate hashes is creating two certificates with the same hash, one having the to-attack domain in it and one a domain you control. Then get the CA to sign the certificate for the domain you control and present the certificate with the attacked domain to the user in SSL.
Dec
1
comment SHA1 - SSL/TLS Cipher Suite
HMAC-SHA-1 used as a MAC is still plenty strong. The problems with the traditional SHA-1 based suites isn't that they use SHA-1, it's that they're using either CBC with encrypt-then-mac (tricky to implement correctly) or RC4.
Dec
1
comment SHA1 - SSL/TLS Cipher Suite
I expect those suites to become less common as AES-GCM and AEAD modes in general gain popularity. TLS 1.3 will probably only support AEAD modes excluding the traditional SHA-1 based suites.