Sean Luke wrote:

> Mersenne Twister has an internal state of 624 longs.  If you fill those 

> longs with a poor-entropy value, or successive poor-entropy values,



Didn't spot this when I first read your email; ec.util.MersenneTwister

has an internal state of 624 /ints/, not 624 longs. FastRNG has the same

amount of internal state (in normal mode, slightly more in secure mode),

but as per the MT19937-64 spec it's organised as 312 64-bit values

instead of 624 32-bit ones.



You may be thinking of old C compilers that defined int as 16 bits and

long as 32 bits. The source for the MersenneTwisterFast class has

several instances of 'a = a&0xffffffff' (where a is an int) with the

comment 'for >32 bit  machines'. Of course this has no effect in Java

because ints are fixed at 32 bits regardless of size.



Michael Wilson

Software Engineer

Purple Frog Text