ref: 1077af5bb8c70351814b5a0042020116b23690d6
dir: /libmp/mpinvert.c/
#include "os.h" #include <mp.h> #define iseven(a) (((a)->p[0] & 1) == 0) // use extended gcd to find the multiplicative inverse // res = b**-1 mod m void mpinvert(mpint *b, mpint *m, mpint *res) { mpint *dc1, *dc2; // don't care dc1 = mpnew(0); dc2 = mpnew(0); mpextendedgcd(b, m, dc1, res, dc2); if(mpcmp(dc1, mpone) != 0) abort(); mpmod(res, m, res); mpfree(dc1); mpfree(dc2); }