a

libsec/egencrypt.c

@@ -0,0 +1,38 @@
+#include "os.h"
+#include <mp.h>
+#include <libsec.h>
+
+mpint*
+egencrypt(EGpub *pub, mpint *in, mpint *out)
+{
+	mpint *m, *k, *gamma, *delta, *pm1;
+	mpint *p = pub->p, *alpha = pub->alpha;
+	int plen = mpsignif(p);
+	int shift = ((plen+Dbits)/Dbits)*Dbits;
+	// in libcrypt version, (int)(LENGTH(pub->p)*sizeof(NumType)*CHARBITS);
+
+	if(out == nil)
+		out = mpnew(0);
+	pm1 = mpnew(0);
+	m = mpnew(0);
+	gamma = mpnew(0);
+	delta = mpnew(0);
+	mpmod(in, p, m);
+	while(1){
+		k = mprand(plen, genrandom, nil);
+		if((mpcmp(mpone, k) <= 0) && (mpcmp(k, pm1) < 0))
+			break;
+	}
+	mpexp(alpha, k, p, gamma);
+	mpexp(pub->key, k, p, delta);
+	mpmul(m, delta, delta);
+	mpmod(delta, p, delta);
+	mpleft(gamma, shift, out);
+	mpadd(delta, out, out);
+	mpfree(pm1);
+	mpfree(m);
+	mpfree(k);
+	mpfree(gamma);
+	mpfree(delta);
+	return out;
+}