Hmm looks like I was wrong... -snip- /* Returns a pseudo-random number between 0 and 32767. */ static int brand () { rseed = rseed * 1103515245 + 12345; return ((unsigned int)((rseed >> 16) & 32767)); /* was % 32768 */ }
>From bash-3.1/variables.c lines 1146-1152 -snip- (copied from http://cer.freeshell.org/renma/LibraryRandomNumber/#LibraryRandomNumber_sec_bash) altough it returns a number between 0 and 32767, it indeed saves a 32 bit number, so the cycle length of this linear congruential generator is actually 2^32. So yes, the seed should be 4 bits and the generator is better then I first tought. Sorry about that, I should have checked the code a bit more careful. Still it is a bad idea to use a PRNG in general, and especially an LCG for password generation. On 4/4/06, Dave English <[EMAIL PROTECTED]> wrote: > In message > <[EMAIL PROTECTED]>, Matthijs > <[EMAIL PROTECTED]> writes > > >By the way, if the random function can only generate numbers between 0 > >and 32767, won't 2 bytes be enough then? The algorithm will perform a > >modulo calculation anyway, so 4 bytes won't really add anything. Of > >course, it is much better then only one byte. > > That will depend on whether the state stored between calls to the PRNG > is only 15-bits, or something larger. > > If more state is stored than is enumerated in the result, then the > generator should have more points on its sequence than 32768 . In that > case then, seeding with more than 15 bits would be worthwhile. > > I have not looked at Bash myself, to see what it actually does > -- > Dave English Senior Software & Systems Engineer > Internet Platform Development, Thus plc > > >