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visits member for 2 years, 3 months
seen Sep 18 '13 at 12:00

Computer engineer: a lot of C, PHP, and Python, plus a bit of lots of other stuff. Linux user. Amateur cryptonerd and general science and math geek.


Sep
18
revised Can PBKDF2 be used to create an XOR cipher key to encrypt random plaintext?
Removed OTP from title, as well.
Sep
18
comment Can PBKDF2 be used to create an XOR cipher key to encrypt random plaintext?
Ugh, sorry about that. I guess I was using it in a kind of colloquial way, but you're right, it's obviously not a real OTP.
Sep
18
comment Can PBKDF2 be used to create an XOR cipher key to encrypt random plaintext?
@CodesInChaos: That's true, but I didn't say anything about an OTP =). I think someone else added that tag, I just removed it.
Sep
18
revised Can PBKDF2 be used to create an XOR cipher key to encrypt random plaintext?
Fixed typo, removed OTP tag.
Oct
26
comment Seed a PRNG with random data and a password
Thanks, nice simple idea.
Oct
26
accepted Seed a PRNG with random data and a password
Oct
24
awarded  Editor
Oct
24
revised Seed a PRNG with random data and a password
Added some more details about the PRNG and seed size.
Oct
24
comment Seed a PRNG with random data and a password
Good question. I guess I've been assuming the key file is the same size as the seed, which I think will be a fair assumption for this application.
Oct
24
asked Seed a PRNG with random data and a password
Jul
27
accepted PRNG taking advantage of very large seed
Jul
27
comment PRNG taking advantage of very large seed
@DavidSchwartz: Ok, I think I finally get it now =). Just use a good PRNG and I don't have to worry about "making the most" of my random seed. That being said, it probably doesn't do any good to use a seed that's bigger than the PRNGs internal state, right?
Jul
17
awarded  Commentator
Jul
17
comment PRNG taking advantage of very large seed
I'm not worried about brute force: I'm worried about patterns in the output if I have to generate thousands of times more data than what is in the seed. Is that what you mean by the strength of the PRNG?
Jul
17
comment PRNG taking advantage of very large seed
@CodeInChaos: Can you elaborate on that? How does several thousand bits of true random data not increase security over 512 bits?
Jul
17
comment PRNG taking advantage of very large seed
Alternatively, if anyone can point me to a good hash function which has a configurable, arbitrarily long output size, I could use that with PBKDF2 with a hash size equal (or almost equal) to the amount of input data I have.
Jul
17
comment PRNG taking advantage of very large seed
Thanks Ricky. No offense, I'm trying to avoid things that people "just came up with" =). I'm hoping there's a standard peer reviewed and time tested technique for doing this. Your idea sounds perfectly reasonable to me, but I'm no expert. Anyway, I think a variant of your idea would be to use Fortuna, or something very Fortuna like (i.e., set the number of entropy pools high enough to cover all of the input data).
Jul
17
asked PRNG taking advantage of very large seed
Mar
20
comment If plaintext is random, how does it affect my choice of encryption algorithm?
No good reason. Mostly just so I didn't have to put in the effort of finding, using, and distributing a library to do the encryption. But given the potential risks, I guess I'll just suck it up and find one =). Thanks for the lead on a new topic to study.
Mar
20
comment If plaintext is random, how does it affect my choice of encryption algorithm?
Thank you, a very clear answer. I feel stupid for not thinking of this =).