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Mar
22
reviewed Approve Security of Diffie Hellman in specific cyclic group
Mar
22
comment Seed / reseed DRBG too often?
@runeks The most common use of a DRBG is to generate unpredictable data (i.e. data that isn't correlated with anything else). You can do that with a DRBG with an unpredictable seed. In my answer I give a few reasons to use a DRBG seeded with /dev/urandom to generate unpredictable data: performance, portability, demonstrable security. It's rare to actually need the determinism aspect; an example use case is when you want to keep logs of everything and you want to be able to repeat a run of the program, e.g. to debug it.
Mar
21
comment Signing MD5 hashes with RSA?
(cont.) Not to say that MD5 shouldn't be replaced, but it's not systematically broken. The points about unpadded RSA are a bigger concern. But the recommended padding mode is PSS (PKCS#1 v1.5 does have weaknesses, not necessarily critical but it shouldn't be used in new protocols).
Mar
21
comment Signing MD5 hashes with RSA?
“it may be possible to create a forged message with the same hash as the message you signed”: no, this is not the case. It is possible to create two messages with the a given prefix and a given suffix. There are situations where this is a dealbreaker, because the attacker can cause the signing party to include a payload in the middle of the message that the attacker controls, with P1 being an inoccuous payload that the signer willingly signs and P2 being a nefarious payload such that the resulting MD5 are the same. But if the message is under full control of the signer then MD5 isn't broken.
Mar
21
revised Signing MD5 hashes with RSA?
added 29 characters in body; edited tags
Mar
21
reviewed Edit what is DHE_EXPORT cipher suite
Mar
21
revised what is DHE_EXPORT cipher suite
Retag - remove irrelevant tag
Mar
20
comment What's the best way to pad a message?
Are you signing or encrypting? Why aren't you using the standard methods (PSS or OAEP)?
Mar
17
reviewed Edit Which encryption is recommended for own messenger
Mar
17
revised Which encryption is recommended for own messenger
add some tags.
Mar
15
revised “Prime conspiracy”'s effect on cryptography
added 30 characters in body; edited title
Mar
9
comment Fast algorithm for reduction modulo a prime
@ArtjomB. This is math that's directly relevant to the design of cryptographic algorithms, and it's about an algorithm which makes it more computer science than math, so I really can't see this question being off-topic here.
Mar
9
reviewed Looks OK Fast algorithm for reduction modulo a prime
Mar
8
revised Yubico's take on U2F key wrapping
edited tags
Mar
8
comment Why haven't we proven many things computationally secure yet?
NP-completeness wouldn't help since it's unproven that this is distinct from P. By the way, there are cryptographic algorithms that are based on NP-complete problems, but they're too slow in practice and there's no reason to think they'd be more robust than other constructions.
Mar
8
revised Why haven't we proven many things computationally secure yet?
edited tags
Mar
8
reviewed Approve Comparison Affine Coordinates and Projective Coordinates Addition in Excel
Mar
8
reviewed Approve How to check that you got the right key when brute forcing an encryption?
Mar
6
reviewed Approve Partially homomorphic addition - not all parties present
Mar
5
reviewed Reject What to do when crib dragging does not work in OTP (One-time pad) ciphers?