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Jun
17
comment Is HMAC needed for a SHA-3 based MAC?
Use the key as prefix not as suffix. Key as suffix is secure as well as long as SHA-3 remains unbroken, but falls once a collision attack is found. If you don't care about the performance cost, still using HMAC is a good choice as well.
Jun
16
comment Functions that are only second-preimage resistant?
@fgrieu I don't see how proving that helps.
Jun
16
reviewed Edit What does it mean that a protocol realizes “strong mutual authentication”?
Jun
16
revised What does it mean that a protocol realizes “strong mutual authentication”?
added 5 characters in body
Jun
16
reviewed Leave Open What are the consequences of not checking the server mac in a TLS connection?
Jun
13
comment RSA decrypting of a huge file by parts
With the edit things get even more confused since RSA private keys aren't used for encryption.
Jun
11
comment Given $n$ bits, how many “truly random” sequences/numbers can be constructed?
@RickyDemer Kolmogorov is cute, but unfortunately very theoretical. Only useful for long messages and cannot be computed. Even simplifications are exponentially expensive.
Jun
11
comment Given $n$ bits, how many “truly random” sequences/numbers can be constructed?
Shannon entropy is only defined for a generation process, not for an individual sequence. If a good generator produces an all zero sequence, that's still perfectly random even if it doesn't look like it.
Jun
7
comment What differences between Menezes–Vanstone ECC and ElGamal ECC?
If you want practical ECC encryption, use ECIES. It's simple and offers strong security.
Jun
6
comment Pick faster private exponent
You could consider multi-prime RSA if your implementation supports it.
Jun
4
comment Padding to increase entropy and size of (otherwise) small JSON objects
If you're using proper encryption (with a per-message IV) you don't need to pad the message.
Jun
4
comment Comparing two values without revealing them
This may be usable as fallback solution, but generally order preserving encryption leaks a bit much. If there is an efficient ZKP, it will be much stronger than OPE.
Jun
4
comment Comparing two values without revealing them
This seems to be a combination of a commitment and a zero knowledge proof. Your hashes solve the commitment part, but make the ZKP part impossible. There is a similar problem called Yao's Millionaires' Problem but there alice knowns one value and bob the other. You should search for "Zero knowledge proof" or perhaps "secure multi party computation".
Jun
3
comment Montgomery Ladder vs Double-and-Add
On montgomery curves montgomery ladders enable cheap addition via differential addition in x/z form. In most other situations I'd rather create a lookup table with 32 or so entries and then double 5 times followed by one lookup and one addition.
Jun
2
revised Is the first version of the Message-Digest algorithm by Ronald Rivest publically available?
edited body
Jun
2
comment Measure ECC key size
When talking about the size in ECC we generally refer to the field size.
Jun
1
comment Parallel hash construction
Related question: Counter mode secure hash algorithm
Jun
1
revised How can one parallelize tasks in CTR-AES for maximum performance?
deleted 9 characters in body
May
28
comment RSA and ECDSA performances
Concerning optimized implementations, ECC has one big advantage: A fixed modulus which usually has been chosen to allow efficient reductions. Certain academics like publishing papers about their world record speed ECC implementations, so ECC has seen quite a bit of optimization work targeting modern CPUs. ECC is more complex mathematically, but I think it's actually easier to write a fast ECC implementation compared to a fast RSA implementation.
May
28
comment Is TEA considered secure?
@user54609 8 byte blocks are annoying to use since it makes encrypting more than a GB using a fixed key problematic. In a quick test TEA was rather slow at 45 cycles per byte. Why do you claim it's "super fast"?