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Oct
21
comment AMD and RDRAND instruction
Intel's HRNG is described in these slides (PDF). You may also be interested in AMD clRNG, which is AMD's OpenCL-based PRNG.
Sep
2
comment POODLE attack on TLS 1.2
@dave_thompson_085 This was mentioned in the answer: "The normal recommendation for POODLE where SSLv3.0 cannot be disabled entirely is to implement TLS_FALLBACK_SCSV support"
Sep
1
comment POODLE attack on TLS 1.2
@HenrickHellström True. I can't remember specifically, but I believe that most practical SSLv3.0 implementations use a single padding length byte at the end, fill the rest with zeros or random data, and don't validate the padding data on receipt. But that's not to say that an implementation couldn't validate padding - it just wouldn't work with most implementations.
Jul
6
comment What is the complexity for attacking 3DES in linear or differential cryptanalysis?
@dave_thompson_085 Fixed the 2^64 error - thanks for spotting that. I left the peta/pebi change out because personally I think it's a bit of a silly distinction, fueled by manufacturers who want to get away with selling smaller drives than what the customer expected from the advertising. But that's a discussion for a different venue ;)
Jul
3
comment Reasons for components of AES
I quite like the terms "confusion and diffusion". Confusion describes taking some quantum of information (e.g. a byte) and turning it into something else, and diffusion describes taking some information and rearranging it so that the information is randomly spread about.
Jun
5
comment Why does anyone use elliptic curves for a CSPRNG?
@SOJPM AES-CTR was just an example - the point I was trying to make is that there other CSPRNG designs out there that don't have the "magic number" problem. That being said, your "provably secure" comment intrigues me - do you have a reference for a proof? I guess the proof relies upon the discrete log problem being known hard?
May
8
comment At what point can you you implement crypto algorithms?
@NeilSmithline Also power analysis.
Apr
6
comment What makes this mixer function resistant to differential cryptanalysis?
Makes sense! Do you have a reference that explains the part about invertible vs. non-invertible s-boxes for SPNs? It sounds like an interesting topic.
Apr
6
comment What makes this mixer function resistant to differential cryptanalysis?
@MaartenBodewes As I said in the post, I was "testing some other randomly conjured up designs" - this construction was just invented by me trying random things.
Apr
2
comment Are there any valid, and person readable, checksums possible?
I think OP is looking for something similar to the PGP word list.
Apr
2
comment What makes this mixer function resistant to differential cryptanalysis?
@Aleph Sorry, I'm not familiar with the term DDT. The s-box is just a randomly generated preset created by shuffling the numbers 0 to 255 - is it likely that this produced a good S-box in terms of differential properties?
Apr
2
comment What makes this mixer function resistant to differential cryptanalysis?
@kodlu 2, on an 8-bit input. Sorry, should've said.
Mar
16
comment Given only RSA public key parameters, what security issues might I be able to detect?
@yyyyyyy I was wondering whether somebody might mention shared factors and other such things. I don't know of any that have affected .NET compilers / IDEs, but I'd be interested to know if anyone has heard of such a thing (either in Microsoft .NET, Mono, or another implementation).
Mar
16
comment Can the same random number be used in encryption and signing?
Another reason is that if the implementation of the signature function is flawed (either in terms of the cryptography involved, or a side-channel attack) in a way that allows key recovery, the attacker would gain the ability to decrypt all messages because she inherently recovers the encryption key too. Where the two keys are distinct, she only gains the ability to forge messages (which may or may not be useful, depending on ciphertext malleability).
Mar
16
comment Where I can find a list of certified software / hardware RNGs compliant to NIST SP 800-22?
I would imagine that you'd need to get your implementation certified, in situ within your product.
Mar
16
comment What is the most light-weight symmetric cipher thats still usefull?
What are your actual limitations? The answer(s) to your question greatly depend on your platform, and how limited your ROM and RAM are.
Mar
16
comment Where I can find a list of certified software / hardware RNGs compliant to NIST SP 800-22?
According to this page, NIST certifies four DRBG techniques, and no NRBGs. It doesn't seem that they've explicitly certified any implementation.
Mar
16
comment CCA-attack is possible in RSA, but how the decryption key $d$ is known to anyone
Are you talking about Bleichenbacher's ACCA attack? My understanding is that it's a padding oracle attack against PKCS#1, which inherently affects RSA, rather than an attack against RSA itself.
Jul
16
comment Can I crack an AES string if I have all these parameters?
@Matthew ... and verify that the result is correct by doing statistical analysis. Remember that AES decryption with incorrect keys just gets you a bunch of incorrect plaintext bytes.
Jul
15
comment Galois field step in XEX mode
Surely $2^n$ over $GF(2^{128})$ is equal to $2^n\ mod\ 2^{128}$?