ref: 5df8776cafe4ed614fa3c4a0f9e1e4f01de228de
dir: /libsec/rsagen.c/
#include "os.h" #include <mp.h> #include <libsec.h> static void genrand(mpint *p, int n) { mpdigit x; // generate n random bits with high set mpbits(p, n); genrandom((uchar*)p->p, (n+7)/8); p->top = (n+Dbits-1)/Dbits; x = 1; x <<= ((n-1)%Dbits); p->p[p->top-1] &= (x-1); p->p[p->top-1] |= x; } RSApriv* rsagen(int nlen, int elen, int rounds) { mpint *p, *q, *e, *d, *phi, *n, *t1, *t2, *kp, *kq, *c2; RSApriv *rsa; p = mpnew(nlen/2); q = mpnew(nlen/2); n = mpnew(nlen); e = mpnew(elen); d = mpnew(0); phi = mpnew(nlen); // create the prime factors and euclid's function genstrongprime(p, nlen/2, rounds); genstrongprime(q, nlen - mpsignif(p) + 1, rounds); mpmul(p, q, n); mpsub(p, mpone, e); mpsub(q, mpone, d); mpmul(e, d, phi); // find an e relatively prime to phi t1 = mpnew(0); t2 = mpnew(0); genrand(e, elen); for(;;){ mpextendedgcd(e, phi, d, t1, t2); if(mpcmp(d, mpone) == 0) break; mpadd(mpone, e, e); } mpfree(t1); mpfree(t2); // d = e**-1 mod phi mpinvert(e, phi, d); // compute chinese remainder coefficient c2 = mpnew(0); mpinvert(p, q, c2); // for crt a**k mod p == (a**(k mod p-1)) mod p kq = mpnew(0); kp = mpnew(0); mpsub(p, mpone, phi); mpmod(d, phi, kp); mpsub(q, mpone, phi); mpmod(d, phi, kq); rsa = rsaprivalloc(); rsa->pub.ek = e; rsa->pub.n = n; rsa->dk = d; rsa->kp = kp; rsa->kq = kq; rsa->p = p; rsa->q = q; rsa->c2 = c2; mpfree(phi); return rsa; }