685 reputation
219
bio website en.wikipedia.org/wiki/…
location United Kingdom
age 26
visits member for 2 years, 4 months
seen Mar 27 at 12:08

Pentester, ex-developer, security researcher, reverse engineer, electronics tinkerer, internet activist, zombie eradicator, promulgator of useless facts, shrubbery inspector, bacon aficionado.

Strengths: Security, Crypto, Win32 API, C#, .NET, PHP, x86 assembly

All answers and comments are encrypted with ROT256-ECB.

Opinions are my own. Advice provided with no warranty.


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.
May
24
asked Memory-hard operations in work-factor hash functions
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?
If you're considering them as an actual security measure, forget it. Crypto is a field where "rolling your own" is a very bad idea.
May
23
asked Is every output of a hash function possible?
May
23
comment Is it secure to use the hash of key as the IV in AES encryption?
@CodeInChaos It's not intended to be some hair-brained "increase the entropies!" scheme, if that's what you're concerned about. The idea is to xor the IV with the hash when storing it in the file, so it can't be known by an attacker without knowing the password.
May
23
comment Is it secure to use the hash of key as the IV in AES encryption?
A solution to this is to store a random IV in the file header, xor'ed with the hash of the password. When you decrypt, compute the password hash and xor against the stored value, then use the result as the IV. This gives you a safe way to store the IV, and a unique IV per file.
May
23
comment Order of cascaded ciphers
Just for reference, if someone sees this answer in future and wonders what custom hardware could crack DES, it's COPACOBANA: copacobana.org
May
23
comment What is the time complexity of the RC4 encryption & decryption algorithms?
Keep in mind, though, that time complexity is practically meaningless as a measure of speed in this sense, because it tells you nothing about how fast the cipher is. If it always takes 10 milliseconds to encrypt a block in a cipher, it's O(n). If it always takes 10 minutes to encrypt a block in a cipher, it's still O(n).
May
23
comment What is the time complexity of the RC4 encryption & decryption algorithms?
Most block ciphers will be O(n) against the number of blocks, yes.
May
23
asked Hash decrypts key, key decrypts cipher… why?
May
23
answered What is the time complexity of the RC4 encryption & decryption algorithms?
May
23
comment Order of cascaded ciphers
@PaŭloEbermann This is purely theoretical, so I'd be interested in the security implications of both.
May
23
comment Order of cascaded ciphers
Interesting. So the optimal solution is to place the two strongest ciphers on the outside? i.e. first and last.
May
22
revised Order of cascaded ciphers
added 69 characters in body
May
21
accepted Security of simple xor and s-box cipher?
May
21
awarded  Scholar
May
21
accepted Is a book cipher provably secure?
May
21
accepted Desirable S-box properties
May
21
asked Order of cascaded ciphers
May
2
awarded  Teacher