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