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 Jul 10 asked Entropy of system data - use all and hash, or trim least significant bits? Jun 6 comment Is there a simple hash function that one can compute without a computer? You can improve your chance of picking a prime by using the 6k±1 rule. Note that this rule only applies one way - all primes fit the rule, but not all numbers that fit the rule are primes. May 30 comment Applying multiple hash functions to improve security? Multiple iterations of the same hash is often useful. However, Ha(Hb(Hc(Hd(message)))) is only as strong as the weakest in the chain. May 30 comment Cryptographic Algorithm/Protocol needed @esskar Don't bother spending money on draconian DRM that won't actually do anything. Instead, get a lawyer to draft up an NDA for all staff that have access to your valuable assets (e.g. source code, design specs, etc) and implement strong working practices to ensure that data can't be leaked accidently. Keep an air-gap between your development network and your internet-access/email network. That way, you can take disciplinary action if someone violates procedure, or legal action if someone violates their NDA. May 27 answered Brute force a ciphered message? May 27 accepted Galois fields in cryptography May 27 comment Galois fields in cryptography This is an amazing answer. I get it now! :) May 26 comment Is it secure to use the hash of key as the IV in AES encryption? @CodeInChaos Paranoia! :) May 25 comment Galois fields in cryptography I'm still lost. I understand vectors as a small set of numbers. So, a vector has a size and a set of values - essentially an array. A vector $[a,b,c,d]$ has a length of 4 and four values - $a$, $b$, $c$, and $d$. If a field is a set of vectors, I envision it as: field = array(array(a1,b1,c1,d1),array(a2,b2,c2,d2),...). Is this correct? If so, how are a1, b1, etc. computed initially, ignoring operators? Or do we just populate them with something (e.g. a key) and then do operations on them? May 25 accepted Standard symbol / notation for “x knows y”, or the inverse May 25 comment Standard symbol / notation for “x knows y”, or the inverse @CodeInChaos I was just using it as an example. If I were really writing that in a document, I'd put something like "where $f(x)$ runs in polynomial time or better". May 25 comment Standard symbol / notation for “x knows y”, or the inverse So you're saying there's no such notation? May 25 asked Standard symbol / notation for “x knows y”, or the inverse May 25 accepted Is every output of a hash function possible? May 25 revised Galois fields in cryptography example May 25 revised Galois fields in cryptography update May 25 comment Galois fields in cryptography <<*snip*>> - I've put this comment as an update to the question. May 24 asked Galois fields in cryptography May 24 comment Memory-hard operations in work-factor hash functions @CodeInChaos I am using scrypt, in my production code. This is just something I'm playing with out of interest, to see how I might go about creating a memory-hard hash function. May 24 comment After implementing a novel encryption algorithm, how would one go about analyzing its security or get help from others in doing so? Can't +1 poncho's comment enough. Learn to break ciphers! I aso recomment Stanford's free crypto course.