| #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); | |
| } |