egencrypt.c (809B)
1 #include "os.h" 2 #include <mp.h> 3 #include <libsec.h> 4 5 mpint* 6 egencrypt(EGpub *pub, mpint *in, mpint *out) 7 { 8 mpint *m, *k, *gamma, *delta, *pm1; 9 mpint *p = pub->p, *alpha = pub->alpha; 10 int plen = mpsignif(p); 11 int shift = ((plen+Dbits)/Dbits)*Dbits; 12 /* in libcrypt version, (int)(LENGTH(pub->p)*sizeof(NumType)*CHARBITS); */ 13 14 if(out == nil) 15 out = mpnew(0); 16 pm1 = mpnew(0); 17 m = mpnew(0); 18 gamma = mpnew(0); 19 delta = mpnew(0); 20 mpmod(in, p, m); 21 while(1){ 22 k = mprand(plen, genrandom, nil); 23 if((mpcmp(mpone, k) <= 0) && (mpcmp(k, pm1) < 0)) 24 break; 25 } 26 mpexp(alpha, k, p, gamma); 27 mpexp(pub->key, k, p, delta); 28 mpmul(m, delta, delta); 29 mpmod(delta, p, delta); 30 mpleft(gamma, shift, out); 31 mpadd(delta, out, out); 32 mpfree(pm1); 33 mpfree(m); 34 mpfree(k); 35 mpfree(gamma); 36 mpfree(delta); 37 return out; 38 }