norm@netcom.com(Norman Hardy) writes: Much has been said recently here about how to produce truly random primes. [snip] The protocol is to accept a sequence of key strokes for printable ASCII characters. [snip] I suggest that if you capture the time in microseconds between keystrokes and insert the least significant 8 bits between the corresponding characters (i. e. <letter1> <time2 - time1> <letter2> <time3 - time2> <letter3> ... <letter nnn> <time until double CR - time nnn>) and MD5 the set of values, the resulting "random" value will be different for both people who type different input texts as well as those people who type the same input text. It is important to be sure that you are accessing a true microsecond clock (or other high resolution clock). For example, in the IBM PC architecture, the clock tic (basic time interrupt) is one per 18.2 milliseconds or 55 interrupts per second. If you were using the clock tic rate and a highly trained typist with a regular typing rate, the interspersed time values might show a consistent set of values. On the other hand, use of a microsecond clock eliminates this problem. As regards the observation that MD5 produces only a 128 bit result, you could call MD5 after each nn values (at least 16) have been entered. In that way a few lines of input and associated timing values could easily generate a value of the same order of magnitude as the number of 1K primes. Martin G. Diehl