Tom Jones says:
Dear Eric and Cypherpunks,
So, how is division defined in Fp?
Being an old fogey, I still refer to the field formed by the integers modulo a prime by a gothic capital Z sub p. In Z_p, you define division as the inverse of multiplcation, just as in real life. One easy way to do this is to note that every number in a field like this has a multiplicative inverse. Multiplying by the multiplicative inverse of a number is the same as dividing by the number. For the hell of it, make yourself a multiplication table for Z_5. Its a quick exercise. Note that every number in Z_5 other than zero possesses a multiplicative inverse -- that is, a number that it can be multiplied against to yield 1. Step back and then observe, experimentally, that for any three positive numbers in Z_5 A, B and C such that A*B=C, that C*(B^-1)=A. One can, of course, prove that this is the case rigorously... Perry