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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.
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?
I think you misunderstood. I'm saying that you shouldn't use your own schemes in practice, for any form of security mechanism in a production environment. You can devise your own schemes and get critique to learn about crypto, but please don't ever use your own cipher to secure sensitive information. Real ciphers have been developed by serious crypto gurus and vetted by hundreds of other serious crypto gurus, over a period of many years. Not a single one of them would use their own cipher without years of peer review and revision.