bgpegcd.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* Copyright (c) 1999 by Sun Microsystems, Inc.
* All rights reserved.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/* Copyright (C) RSA Data Security, Inc. created 1986, 1996. This is an
unpublished work protected as such under copyright law. This work
contains proprietary, confidential, and trade secret information of
RSA Data Security, Inc. Use, disclosure or reproduction without the
express written authorization of RSA Data Security, Inc. is
prohibited.
*/
#include "port_before.h"
#include "global.h"
#include "bigmath.h"
#include "port_after.h"
/* BigPegcd
input
u, v bignums
k int size of u, v regs
restriction u, v positive
output
u3=GCD (u, v) (pos)
u1=inv (u)modv (pos)
u2=inv (v)modu (pos)
if GCD (u, v)!=1 then u1, u2 st
u3=u * u1mod (v) & u3=v * u2mod (u)
(see KNUTH vol 2)
*/
void BigPegcd (u3, u1, u2, u, v, k)
UINT2 *u3, *u2, *u1, *u, *v;
unsigned int k;
{
UINT2 v1[2 * MAX_RSA_PRIME_WORDS], v2[2 * MAX_RSA_PRIME_WORDS],
v3[2 * MAX_RSA_PRIME_WORDS], q[2 * MAX_RSA_PRIME_WORDS],
r[2 * MAX_RSA_PRIME_WORDS], t1[2 * MAX_RSA_PRIME_WORDS],
t2[2 * MAX_RSA_PRIME_WORDS], t3[2 * MAX_RSA_PRIME_WORDS];
BigConst (u1, 1, k);
BigConst (u2, 0, k);
BigCopy (u3, u, k);
BigConst (v1, 0, k);
BigConst (v2, 1, k);
BigCopy (v3, v, k);
/* Begin calc.
*/
while (1) {
if (BigSign (v3, k) == 0)
break;
BigPdiv (q, r, u3, v3, k, k);
BigPmpyl (t1, v1, q, k);
BigPmpyl (t2, v2, q, k);
BigPmpyl (t3, v3, q, k);
BigSub (t1, u1, t1, k);
BigSub (t2, u2, t2, k);
BigSub (t3, u3, t3, k);
BigCopy (u1, v1, k);
BigCopy (u2, v2, k);
BigCopy (u3, v3, k);
BigCopy (v1, t1, k);
BigCopy (v2, t2, k);
BigCopy (v3, t3, k);
}
if (BigSign (u1, k) == -1)
/* make positive */
BigAdd (u1, u1, v, k);
if (BigSign (u2, k) == -1)
/* make positive */
BigAdd (u2, u2, u, k);
T_memset ((POINTER)v1, 0, sizeof (v1));
T_memset ((POINTER)v2, 0, sizeof (v2));
T_memset ((POINTER)v3, 0, sizeof (v3));
T_memset ((POINTER)q, 0, sizeof (q));
T_memset ((POINTER)r, 0, sizeof (r));
T_memset ((POINTER)t1, 0, sizeof (t1));
T_memset ((POINTER)t2, 0, sizeof (t2));
T_memset ((POINTER)t3, 0, sizeof (t3));
}