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#1
November 6th, 2005, 03:30 AM
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Cryptographically secure random file generator
Does anyone know of a cryptographically secure random file generator?
Not a random number generator, mind you, a random file generator -- which is, granted, basically just a random number generator that loops a lot and sends the output to a file rather than the screen. But it's critical that the "random" values generated be cryptographically strong, meaning that it should be impossible to asertain the input that was used to generate the random data AND it should be as physically impossible as possible to reconstruct the exact conditions of input that were used to generate the random data. (It's easy to simply use rand() % 256, but, given the source code, it's potentially too easy [for a professional] to reconstruct the exact input condiions that were used to seed rand().) Does anyone know of such a program that will do that? Specifically, it'd be nice if it were F/OSS, so I can also study it (when I get the spare time).
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#2
November 6th, 2005, 10:33 PM
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The code isn't exactly "easy reading," but you may want to take a look at drivers/char/random.c in the Linux kernel source code (or the similar source file(s) in a *BSD system). That's what provides the entropy-driven random byte sequence character device. According to the comments in the source code, this method is cryptographically strong.
Hope that helps.
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#3
November 11th, 2005, 09:15 PM
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well in linux you could possible us python2.4 which includes a cryptographicly secure random number generator with this simple code you could put as meny bytes as you would like into a file
Code:
#!/usr/bin/python
import os
f = open("/url/to/file", "w")
#replace 55 below with number of random bytes
randData = os.urandom(55)
f.write(randData)
f.close()
this uses linuxes urandom function which is cryptographicly secure. Also just to note you must have python 2.4 and up for this to work. I can write a java one that will work if python 2.4 isn't an option.
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