Subversion Repositories planix.SVN

#include "os.h"
#include <mp.h>
#include <libsec.h>

EGsig*
egsign(EGpriv *priv, mpint *m)
{
        EGpub *pub = &priv->pub;
        EGsig *sig;
        mpint *pm1, *k, *kinv, *r, *s;
        mpint *p = pub->p, *alpha = pub->alpha;
        int plen = mpsignif(p);

        pm1 = mpnew(0);
        kinv = mpnew(0);
        r = mpnew(0);
        s = mpnew(0);
        k = mpnew(0);
        mpsub(p, mpone, pm1);
        while(1){
                mprand(plen, genrandom, k);
                if((mpcmp(mpone, k) > 0) || (mpcmp(k, pm1) >= 0))
                        continue;
                mpextendedgcd(k, pm1, r, kinv, s);
                if(mpcmp(r, mpone) != 0)
                        continue;
                break;
        }
        mpmod(kinv, pm1, kinv);  // make kinv positive
        mpexp(alpha, k, p, r);
        mpmul(priv->secret, r, s);
        mpmod(s, pm1, s);
        mpsub(m, s, s);
        mpmul(kinv, s, s);
        mpmod(s, pm1, s);
        sig = egsigalloc();
        sig->r = r;
        sig->s = s;
        mpfree(pm1);
        mpfree(k);
        mpfree(kinv);
        return sig;
}