genprime.c (544B)
1 #include "os.h" 2 #include <mp.h> 3 #include <libsec.h> 4 5 /* generate a probable prime. accuracy is the miller-rabin interations */ 6 void 7 genprime(mpint *p, int n, int accuracy) 8 { 9 mpdigit x; 10 11 /* generate n random bits with high and low bits set */ 12 mpbits(p, n); 13 genrandom((uchar*)p->p, (n+7)/8); 14 p->top = (n+Dbits-1)/Dbits; 15 x = 1; 16 x <<= ((n-1)%Dbits); 17 p->p[p->top-1] &= (x-1); 18 p->p[p->top-1] |= x; 19 p->p[0] |= 1; 20 21 /* keep icrementing till it looks prime */ 22 for(;;){ 23 if(probably_prime(p, accuracy)) 24 break; 25 mpadd(p, mptwo, p); 26 } 27 }