1*8ccd4a63SDavid du Colombier #include "os.h"
2*8ccd4a63SDavid du Colombier #include <mp.h>
3*8ccd4a63SDavid du Colombier #include <libsec.h>
4*8ccd4a63SDavid du Colombier
5*8ccd4a63SDavid du Colombier EGsig*
egsign(EGpriv * priv,mpint * m)6*8ccd4a63SDavid du Colombier egsign(EGpriv *priv, mpint *m)
7*8ccd4a63SDavid du Colombier {
8*8ccd4a63SDavid du Colombier EGpub *pub = &priv->pub;
9*8ccd4a63SDavid du Colombier EGsig *sig;
10*8ccd4a63SDavid du Colombier mpint *pm1, *k, *kinv, *r, *s;
11*8ccd4a63SDavid du Colombier mpint *p = pub->p, *alpha = pub->alpha;
12*8ccd4a63SDavid du Colombier int plen = mpsignif(p);
13*8ccd4a63SDavid du Colombier
14*8ccd4a63SDavid du Colombier pm1 = mpnew(0);
15*8ccd4a63SDavid du Colombier kinv = mpnew(0);
16*8ccd4a63SDavid du Colombier r = mpnew(0);
17*8ccd4a63SDavid du Colombier s = mpnew(0);
18*8ccd4a63SDavid du Colombier k = mpnew(0);
19*8ccd4a63SDavid du Colombier mpsub(p, mpone, pm1);
20*8ccd4a63SDavid du Colombier while(1){
21*8ccd4a63SDavid du Colombier mprand(plen, genrandom, k);
22*8ccd4a63SDavid du Colombier if((mpcmp(mpone, k) > 0) || (mpcmp(k, pm1) >= 0))
23*8ccd4a63SDavid du Colombier continue;
24*8ccd4a63SDavid du Colombier mpextendedgcd(k, pm1, r, kinv, s);
25*8ccd4a63SDavid du Colombier if(mpcmp(r, mpone) != 0)
26*8ccd4a63SDavid du Colombier continue;
27*8ccd4a63SDavid du Colombier break;
28*8ccd4a63SDavid du Colombier }
29*8ccd4a63SDavid du Colombier mpmod(kinv, pm1, kinv); // make kinv positive
30*8ccd4a63SDavid du Colombier mpexp(alpha, k, p, r);
31*8ccd4a63SDavid du Colombier mpmul(priv->secret, r, s);
32*8ccd4a63SDavid du Colombier mpmod(s, pm1, s);
33*8ccd4a63SDavid du Colombier mpsub(m, s, s);
34*8ccd4a63SDavid du Colombier mpmul(kinv, s, s);
35*8ccd4a63SDavid du Colombier mpmod(s, pm1, s);
36*8ccd4a63SDavid du Colombier sig = egsigalloc();
37*8ccd4a63SDavid du Colombier sig->r = r;
38*8ccd4a63SDavid du Colombier sig->s = s;
39*8ccd4a63SDavid du Colombier mpfree(pm1);
40*8ccd4a63SDavid du Colombier mpfree(k);
41*8ccd4a63SDavid du Colombier mpfree(kinv);
42*8ccd4a63SDavid du Colombier return sig;
43*8ccd4a63SDavid du Colombier }
44