Re: java.security expert?

[Casey Marshall]

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>>>>> "Tom" == Tom Tromey <address@hidden> writes:

Tom>     //Step 1 - generate prime
Tom>     BigInteger p = new BigInteger( (pmax + pmin)/2, new Random() );

This uses a simple linear congruential PRNG seeded with the current
time to generate the number, which really isn't secure.

Tom> +          //Step 7.1 - test primality
Tom> +          if( p.isProbablePrime( 1 ) == true )
Tom> +            {

This is almost certainly wrong. isProbablePrime(n) will return `true'
correctly (i.e. when the number is actually prime) with a probability
of 1 - 1 / 2^n, meaning that the above lies about a prime 1/2 the
time. This is bad, especially when the security of your system depends
on large prime. 

Where is this used? It is probably a better idea to use just the
constructor of BigInteger that generates random primes, and to use a
well-seeded instance of SecureRandom to pass it. The prime test in
BigInteger (probably Miller-Rabin) is good enough.

Also `== true' is just silly. I say we dust off and nuke the site from
orbit. It's the only way to be sure.

- -- 
Casey Marshall || address@hidden
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