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#include "os.h"
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#include <mp.h>
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#include <libsec.h>
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EGsig*
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egsign(EGpriv *priv, mpint *m)
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{
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	EGpub *pub = &priv->pub;
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	EGsig *sig;
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	mpint *pm1, *k, *kinv, *r, *s;
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	mpint *p = pub->p, *alpha = pub->alpha;
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	int plen = mpsignif(p);
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	pm1 = mpnew(0);
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	kinv = mpnew(0);
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	r = mpnew(0);
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	s = mpnew(0);
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	k = mpnew(0);
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	mpsub(p, mpone, pm1);
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	while(1){
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		mprand(plen, genrandom, k);
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		if((mpcmp(mpone, k) > 0) || (mpcmp(k, pm1) >= 0))
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			continue;
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		mpextendedgcd(k, pm1, r, kinv, s);
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		if(mpcmp(r, mpone) != 0)
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			continue;
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		break;
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	}
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	mpmod(kinv, pm1, kinv);  // make kinv positive
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	mpexp(alpha, k, p, r);
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	mpmul(priv->secret, r, s);
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	mpmod(s, pm1, s);
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	mpsub(m, s, s);
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	mpmul(kinv, s, s);
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	mpmod(s, pm1, s);
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	sig = egsigalloc();
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	sig->r = r;
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	sig->s = s;
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	mpfree(pm1);
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	mpfree(k);
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	mpfree(kinv);
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	return sig;
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}