#include "os.h"#include <mp.h>#include <libsec.h> DSAsig*dsasign(DSApriv *priv, mpint *m){	DSApub *pub = &priv->pub;	DSAsig *sig;	mpint *qm1, *k, *kinv, *r, *s;	mpint *q = pub->q, *p = pub->p, *alpha = pub->alpha;	int qlen = mpsignif(q); 	qm1 = mpnew(0);	kinv = mpnew(0);	r = mpnew(0);	s = mpnew(0);	k = mpnew(0);	mpsub(pub->q, mpone, qm1); 	// find a k that has an inverse mod q	while(1){		mprand(qlen, genrandom, k);		if((mpcmp(mpone, k) > 0) || (mpcmp(k, pub->q) >= 0))			continue;		mpextendedgcd(k, q, r, kinv, s);		if(mpcmp(r, mpone) != 0)			sysfatal("dsasign: pub->q not prime");		break;	}   	// make kinv positive	mpmod(kinv, pub->q, kinv); 	// r = ((alpha**k) mod p) mod q	mpexp(alpha, k, p, r);	mpmod(r, q, r); 	// s = (kinv*(m + ar)) mod q	mpmul(r, priv->secret, s);	mpadd(s, m, s);	mpmul(s, kinv, s);	mpmod(s, q, s); 	sig = dsasigalloc();	sig->r = r;	sig->s = s;	mpfree(qm1);	mpfree(k);	mpfree(kinv);	return sig;}