Thomas
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 Feb 9 answered brute force attack on KDF vs KEY Feb 9 comment Name for identical operations for encryption and decryption This is not worth an answer, but the closest mathematical term I can think of would be an involution. I am not sure if there is a cryptographic term for primitives which satisfy this property. Feb 8 comment AES implementation in java that allows key of 320-bit length Key derivation function. Feb 7 reviewed Reject Are there two known strings which have the same MD5 hash value? Feb 7 comment How to best obtain bit sequences from throwing normal dice? @PaŭloEbermann To be fair the term "subcritical" is usually used in the context of probability distributions and not events, but I like to use it to highlight a particular asymptotic behaviour at probability 1. Feb 6 comment How to best obtain bit sequences from throwing normal dice? @PaŭloEbermann Yes, subcritical means less than 1. As long as the probability is less than 1 the algorithm will terminate and the expected number of rolls is finite (though it tends to infinity as the probability approaches 1) Feb 6 comment How to check the strength of an encryption algorithm? @Mok-KongShen And therefore, bitwise addition is a "primitive" as well. Where should the line be drawn? Obviously, where it matters, and that is always at protocol level (below that, we're talking more about "mathematical primitives" than anything else). Put differently, an S-Box provides no security properties on its own - it is merely a more or less nonlinear mapping - but does in the context of a cipher or a hash function - like DES - where its nonlinearity can be assessed with respect to criteria such as resistance to linear/differential cryptanalysis, etc... Feb 6 comment How to check the strength of an encryption algorithm? If you want to learn cryptography: break first, design later. Feb 6 comment RSA primes vs. largest known primes It is also possible to select an integer in such a way that deterministically proving its primality be efficient (general-purpose deterministic tests are kind of slow, but for instance knowing the factorization of $p - 1$ helps a lot) should you need that. Most cryptographic applications don't need to unconditionally guarantee the integer is prime (so they just pick at random) but sometimes a primality certificate may be desirable. Feb 5 comment How to check the strength of an encryption algorithm? If you have to ask, it's not secure at all. Feb 4 comment Entropy in natural language texts How is collecting a huge library of texts, and generating something that sort-of kind-of looks random from it, simpler and less awkward than generating 128-256 pseudorandom bits from a well-vetted and easily accessible source of entropy? Your scheme doesn't even let you measure the amount of entropy you're collecting to any degree of accuracy ("entropy" is a lot more than just "english text has 0.6 to 1.3 bits of entropy per character"). Feb 4 comment Entropy in natural language texts Which is exactly what I said. What advantage does your scheme have over, say, using AES? And what advantages does AES have over yours? In your application, that is. Feb 4 comment Entropy in natural language texts But since you - obviously - no longer have unconditional security, what advantages does this awkward and complicated scheme have over just using generic cryptographic primitives? Feb 2 awarded Custodian Feb 2 reviewed Needs Improvement Two step encryption Feb 2 reviewed Satisfactory Future-Proof Versioning and Validation Feb 2 reviewed Satisfactory FIPS 140 compliance for encrypted files Feb 2 reviewed Satisfactory Blind quantum computing and fully homomorphic encryption Feb 2 reviewed Excellent What exactly is a negligible (and non-negligible) function? Feb 2 reviewed Satisfactory Does RSA-OEAP have integrity and authenticity properties?