Add most of libsec.

1 files changed, 70 insertions, 0 deletions

diff --git a/src/libsec/port/rsagen.c b/src/libsec/port/rsagen.c
new file mode 100644
index 00000000..ebe1079d
--- /dev/null
+++ b/src/libsec/port/rsagen.c
@@ -0,0 +1,70 @@
+#include "os.h"
+#include <mp.h>
+#include <libsec.h>
+
+RSApriv*
+rsagen(int nlen, int elen, int rounds)
+{
+	mpint *p, *q, *e, *d, *phi, *n, *t1, *t2, *kp, *kq, *c2;
+	RSApriv *rsa;
+
+	p = mpnew(nlen/2);
+	q = mpnew(nlen/2);
+	n = mpnew(nlen);
+	e = mpnew(elen);
+	d = mpnew(0);
+	phi = mpnew(nlen);
+
+	// create the prime factors and euclid's function
+	genprime(p, nlen/2, rounds);
+	genprime(q, nlen - mpsignif(p) + 1, rounds);
+	mpmul(p, q, n);
+	mpsub(p, mpone, e);
+	mpsub(q, mpone, d);
+	mpmul(e, d, phi);
+
+	// find an e relatively prime to phi
+	t1 = mpnew(0);
+	t2 = mpnew(0);
+	mprand(elen, genrandom, e);
+	if(mpcmp(e,mptwo) <= 0)
+		itomp(3, e);
+	// See Menezes et al. p.291 "8.8 Note (selecting primes)" for discussion
+	// of the merits of various choices of primes and exponents.  e=3 is a
+	// common and recommended exponent, but doesn't necessarily work here
+	// because we chose strong rather than safe primes.
+	for(;;){
+		mpextendedgcd(e, phi, t1, d, t2);
+		if(mpcmp(t1, mpone) == 0)
+			break;
+		mpadd(mpone, e, e);
+	}
+	mpfree(t1);
+	mpfree(t2);
+
+	// compute chinese remainder coefficient
+	c2 = mpnew(0);
+	mpinvert(p, q, c2);
+
+	// for crt a**k mod p == (a**(k mod p-1)) mod p
+	kq = mpnew(0);
+	kp = mpnew(0);
+	mpsub(p, mpone, phi);
+	mpmod(d, phi, kp);
+	mpsub(q, mpone, phi);
+	mpmod(d, phi, kq);
+
+	rsa = rsaprivalloc();
+	rsa->pub.ek = e;
+	rsa->pub.n = n;
+	rsa->dk = d;
+	rsa->kp = kp;
+	rsa->kq = kq;
+	rsa->p = p;
+	rsa->q = q;
+	rsa->c2 = c2;
+
+	mpfree(phi);
+
+	return rsa;
+}