Java example source code file (ec.c)
The ec.c Java example source code
/*
* Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved.
* Use is subject to license terms.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/* *********************************************************************
*
* The Original Code is the Elliptic Curve Cryptography library.
*
* The Initial Developer of the Original Code is
* Sun Microsystems, Inc.
* Portions created by the Initial Developer are Copyright (C) 2003
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Dr Vipul Gupta <vipul.gupta@sun.com> and
* Douglas Stebila <douglas@stebila.ca>, Sun Microsystems Laboratories
*
*********************************************************************** */
#include "mplogic.h"
#include "ec.h"
#include "ecl.h"
#include <sys/types.h>
#ifndef _KERNEL
#include <stdlib.h>
#include <string.h>
#ifndef _WIN32
#include <stdio.h>
#include <strings.h>
#endif /* _WIN32 */
#endif
#include "ecl-exp.h"
#include "mpi.h"
#include "ecc_impl.h"
#ifdef _KERNEL
#define PORT_ZFree(p, l) bzero((p), (l)); kmem_free((p), (l))
#else
#ifndef _WIN32
#define PORT_ZFree(p, l) bzero((p), (l)); free((p))
#else
#define PORT_ZFree(p, l) memset((p), 0, (l)); free((p))
#endif /* _WIN32 */
#endif
/*
* Returns true if pointP is the point at infinity, false otherwise
*/
PRBool
ec_point_at_infinity(SECItem *pointP)
{
unsigned int i;
for (i = 1; i < pointP->len; i++) {
if (pointP->data[i] != 0x00) return PR_FALSE;
}
return PR_TRUE;
}
/*
* Computes scalar point multiplication pointQ = k1 * G + k2 * pointP for
* the curve whose parameters are encoded in params with base point G.
*/
SECStatus
ec_points_mul(const ECParams *params, const mp_int *k1, const mp_int *k2,
const SECItem *pointP, SECItem *pointQ, int kmflag)
{
mp_int Px, Py, Qx, Qy;
mp_int Gx, Gy, order, irreducible, a, b;
#if 0 /* currently don't support non-named curves */
unsigned int irr_arr[5];
#endif
ECGroup *group = NULL;
SECStatus rv = SECFailure;
mp_err err = MP_OKAY;
unsigned int len;
#if EC_DEBUG
int i;
char mpstr[256];
printf("ec_points_mul: params [len=%d]:", params->DEREncoding.len);
for (i = 0; i < params->DEREncoding.len; i++)
printf("%02x:", params->DEREncoding.data[i]);
printf("\n");
if (k1 != NULL) {
mp_tohex(k1, mpstr);
printf("ec_points_mul: scalar k1: %s\n", mpstr);
mp_todecimal(k1, mpstr);
printf("ec_points_mul: scalar k1: %s (dec)\n", mpstr);
}
if (k2 != NULL) {
mp_tohex(k2, mpstr);
printf("ec_points_mul: scalar k2: %s\n", mpstr);
mp_todecimal(k2, mpstr);
printf("ec_points_mul: scalar k2: %s (dec)\n", mpstr);
}
if (pointP != NULL) {
printf("ec_points_mul: pointP [len=%d]:", pointP->len);
for (i = 0; i < pointP->len; i++)
printf("%02x:", pointP->data[i]);
printf("\n");
}
#endif
/* NOTE: We only support uncompressed points for now */
len = (params->fieldID.size + 7) >> 3;
if (pointP != NULL) {
if ((pointP->data[0] != EC_POINT_FORM_UNCOMPRESSED) ||
(pointP->len != (2 * len + 1))) {
return SECFailure;
};
}
MP_DIGITS(&Px) = 0;
MP_DIGITS(&Py) = 0;
MP_DIGITS(&Qx) = 0;
MP_DIGITS(&Qy) = 0;
MP_DIGITS(&Gx) = 0;
MP_DIGITS(&Gy) = 0;
MP_DIGITS(&order) = 0;
MP_DIGITS(&irreducible) = 0;
MP_DIGITS(&a) = 0;
MP_DIGITS(&b) = 0;
CHECK_MPI_OK( mp_init(&Px, kmflag) );
CHECK_MPI_OK( mp_init(&Py, kmflag) );
CHECK_MPI_OK( mp_init(&Qx, kmflag) );
CHECK_MPI_OK( mp_init(&Qy, kmflag) );
CHECK_MPI_OK( mp_init(&Gx, kmflag) );
CHECK_MPI_OK( mp_init(&Gy, kmflag) );
CHECK_MPI_OK( mp_init(&order, kmflag) );
CHECK_MPI_OK( mp_init(&irreducible, kmflag) );
CHECK_MPI_OK( mp_init(&a, kmflag) );
CHECK_MPI_OK( mp_init(&b, kmflag) );
if ((k2 != NULL) && (pointP != NULL)) {
/* Initialize Px and Py */
CHECK_MPI_OK( mp_read_unsigned_octets(&Px, pointP->data + 1, (mp_size) len) );
CHECK_MPI_OK( mp_read_unsigned_octets(&Py, pointP->data + 1 + len, (mp_size) len) );
}
/* construct from named params, if possible */
if (params->name != ECCurve_noName) {
group = ECGroup_fromName(params->name, kmflag);
}
#if 0 /* currently don't support non-named curves */
if (group == NULL) {
/* Set up mp_ints containing the curve coefficients */
CHECK_MPI_OK( mp_read_unsigned_octets(&Gx, params->base.data + 1,
(mp_size) len) );
CHECK_MPI_OK( mp_read_unsigned_octets(&Gy, params->base.data + 1 + len,
(mp_size) len) );
SECITEM_TO_MPINT( params->order, &order );
SECITEM_TO_MPINT( params->curve.a, &a );
SECITEM_TO_MPINT( params->curve.b, &b );
if (params->fieldID.type == ec_field_GFp) {
SECITEM_TO_MPINT( params->fieldID.u.prime, &irreducible );
group = ECGroup_consGFp(&irreducible, &a, &b, &Gx, &Gy, &order, params->cofactor);
} else {
SECITEM_TO_MPINT( params->fieldID.u.poly, &irreducible );
irr_arr[0] = params->fieldID.size;
irr_arr[1] = params->fieldID.k1;
irr_arr[2] = params->fieldID.k2;
irr_arr[3] = params->fieldID.k3;
irr_arr[4] = 0;
group = ECGroup_consGF2m(&irreducible, irr_arr, &a, &b, &Gx, &Gy, &order, params->cofactor);
}
}
#endif
if (group == NULL)
goto cleanup;
if ((k2 != NULL) && (pointP != NULL)) {
CHECK_MPI_OK( ECPoints_mul(group, k1, k2, &Px, &Py, &Qx, &Qy) );
} else {
CHECK_MPI_OK( ECPoints_mul(group, k1, NULL, NULL, NULL, &Qx, &Qy) );
}
/* Construct the SECItem representation of point Q */
pointQ->data[0] = EC_POINT_FORM_UNCOMPRESSED;
CHECK_MPI_OK( mp_to_fixlen_octets(&Qx, pointQ->data + 1,
(mp_size) len) );
CHECK_MPI_OK( mp_to_fixlen_octets(&Qy, pointQ->data + 1 + len,
(mp_size) len) );
rv = SECSuccess;
#if EC_DEBUG
printf("ec_points_mul: pointQ [len=%d]:", pointQ->len);
for (i = 0; i < pointQ->len; i++)
printf("%02x:", pointQ->data[i]);
printf("\n");
#endif
cleanup:
ECGroup_free(group);
mp_clear(&Px);
mp_clear(&Py);
mp_clear(&Qx);
mp_clear(&Qy);
mp_clear(&Gx);
mp_clear(&Gy);
mp_clear(&order);
mp_clear(&irreducible);
mp_clear(&a);
mp_clear(&b);
if (err) {
MP_TO_SEC_ERROR(err);
rv = SECFailure;
}
return rv;
}
/* Generates a new EC key pair. The private key is a supplied
* value and the public key is the result of performing a scalar
* point multiplication of that value with the curve's base point.
*/
SECStatus
ec_NewKey(ECParams *ecParams, ECPrivateKey **privKey,
const unsigned char *privKeyBytes, int privKeyLen, int kmflag)
{
SECStatus rv = SECFailure;
PRArenaPool *arena;
ECPrivateKey *key;
mp_int k;
mp_err err = MP_OKAY;
int len;
#if EC_DEBUG
printf("ec_NewKey called\n");
#endif
if (!ecParams || !privKey || !privKeyBytes || (privKeyLen < 0)) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
/* Initialize an arena for the EC key. */
if (!(arena = PORT_NewArena(NSS_FREEBL_DEFAULT_CHUNKSIZE)))
return SECFailure;
key = (ECPrivateKey *)PORT_ArenaZAlloc(arena, sizeof(ECPrivateKey),
kmflag);
if (!key) {
PORT_FreeArena(arena, PR_TRUE);
return SECFailure;
}
/* Set the version number (SEC 1 section C.4 says it should be 1) */
SECITEM_AllocItem(arena, &key->version, 1, kmflag);
key->version.data[0] = 1;
/* Copy all of the fields from the ECParams argument to the
* ECParams structure within the private key.
*/
key->ecParams.arena = arena;
key->ecParams.type = ecParams->type;
key->ecParams.fieldID.size = ecParams->fieldID.size;
key->ecParams.fieldID.type = ecParams->fieldID.type;
if (ecParams->fieldID.type == ec_field_GFp) {
CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.fieldID.u.prime,
&ecParams->fieldID.u.prime, kmflag));
} else {
CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.fieldID.u.poly,
&ecParams->fieldID.u.poly, kmflag));
}
key->ecParams.fieldID.k1 = ecParams->fieldID.k1;
key->ecParams.fieldID.k2 = ecParams->fieldID.k2;
key->ecParams.fieldID.k3 = ecParams->fieldID.k3;
CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.curve.a,
&ecParams->curve.a, kmflag));
CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.curve.b,
&ecParams->curve.b, kmflag));
CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.curve.seed,
&ecParams->curve.seed, kmflag));
CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.base,
&ecParams->base, kmflag));
CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.order,
&ecParams->order, kmflag));
key->ecParams.cofactor = ecParams->cofactor;
CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.DEREncoding,
&ecParams->DEREncoding, kmflag));
key->ecParams.name = ecParams->name;
CHECK_SEC_OK(SECITEM_CopyItem(arena, &key->ecParams.curveOID,
&ecParams->curveOID, kmflag));
len = (ecParams->fieldID.size + 7) >> 3;
SECITEM_AllocItem(arena, &key->publicValue, 2*len + 1, kmflag);
len = ecParams->order.len;
SECITEM_AllocItem(arena, &key->privateValue, len, kmflag);
/* Copy private key */
if (privKeyLen >= len) {
memcpy(key->privateValue.data, privKeyBytes, len);
} else {
memset(key->privateValue.data, 0, (len - privKeyLen));
memcpy(key->privateValue.data + (len - privKeyLen), privKeyBytes, privKeyLen);
}
/* Compute corresponding public key */
MP_DIGITS(&k) = 0;
CHECK_MPI_OK( mp_init(&k, kmflag) );
CHECK_MPI_OK( mp_read_unsigned_octets(&k, key->privateValue.data,
(mp_size) len) );
rv = ec_points_mul(ecParams, &k, NULL, NULL, &(key->publicValue), kmflag);
if (rv != SECSuccess) goto cleanup;
*privKey = key;
cleanup:
mp_clear(&k);
if (rv) {
PORT_FreeArena(arena, PR_TRUE);
}
#if EC_DEBUG
printf("ec_NewKey returning %s\n",
(rv == SECSuccess) ? "success" : "failure");
#endif
return rv;
}
/* Generates a new EC key pair. The private key is a supplied
* random value (in seed) and the public key is the result of
* performing a scalar point multiplication of that value with
* the curve's base point.
*/
SECStatus
EC_NewKeyFromSeed(ECParams *ecParams, ECPrivateKey **privKey,
const unsigned char *seed, int seedlen, int kmflag)
{
SECStatus rv = SECFailure;
rv = ec_NewKey(ecParams, privKey, seed, seedlen, kmflag);
return rv;
}
/* Generate a random private key using the algorithm A.4.1 of ANSI X9.62,
* modified a la FIPS 186-2 Change Notice 1 to eliminate the bias in the
* random number generator.
*
* Parameters
* - order: a buffer that holds the curve's group order
* - len: the length in octets of the order buffer
* - random: a buffer of 2 * len random bytes
* - randomlen: the length in octets of the random buffer
*
* Return Value
* Returns a buffer of len octets that holds the private key. The caller
* is responsible for freeing the buffer with PORT_ZFree.
*/
static unsigned char *
ec_GenerateRandomPrivateKey(const unsigned char *order, int len,
const unsigned char *random, int randomlen, int kmflag)
{
SECStatus rv = SECSuccess;
mp_err err;
unsigned char *privKeyBytes = NULL;
mp_int privKeyVal, order_1, one;
MP_DIGITS(&privKeyVal) = 0;
MP_DIGITS(&order_1) = 0;
MP_DIGITS(&one) = 0;
CHECK_MPI_OK( mp_init(&privKeyVal, kmflag) );
CHECK_MPI_OK( mp_init(&order_1, kmflag) );
CHECK_MPI_OK( mp_init(&one, kmflag) );
/*
* Reduces the 2*len buffer of random bytes modulo the group order.
*/
if ((privKeyBytes = PORT_Alloc(2*len, kmflag)) == NULL) goto cleanup;
if (randomlen != 2 * len) {
randomlen = 2 * len;
}
/* No need to generate - random bytes are now supplied */
/* CHECK_SEC_OK( RNG_GenerateGlobalRandomBytes(privKeyBytes, 2*len) );*/
memcpy(privKeyBytes, random, randomlen);
CHECK_MPI_OK( mp_read_unsigned_octets(&privKeyVal, privKeyBytes, 2*len) );
CHECK_MPI_OK( mp_read_unsigned_octets(&order_1, order, len) );
CHECK_MPI_OK( mp_set_int(&one, 1) );
CHECK_MPI_OK( mp_sub(&order_1, &one, &order_1) );
CHECK_MPI_OK( mp_mod(&privKeyVal, &order_1, &privKeyVal) );
CHECK_MPI_OK( mp_add(&privKeyVal, &one, &privKeyVal) );
CHECK_MPI_OK( mp_to_fixlen_octets(&privKeyVal, privKeyBytes, len) );
memset(privKeyBytes+len, 0, len);
cleanup:
mp_clear(&privKeyVal);
mp_clear(&order_1);
mp_clear(&one);
if (err < MP_OKAY) {
MP_TO_SEC_ERROR(err);
rv = SECFailure;
}
if (rv != SECSuccess && privKeyBytes) {
#ifdef _KERNEL
kmem_free(privKeyBytes, 2*len);
#else
free(privKeyBytes);
#endif
privKeyBytes = NULL;
}
return privKeyBytes;
}
/* Generates a new EC key pair. The private key is a random value and
* the public key is the result of performing a scalar point multiplication
* of that value with the curve's base point.
*/
SECStatus
EC_NewKey(ECParams *ecParams, ECPrivateKey **privKey,
const unsigned char* random, int randomlen, int kmflag)
{
SECStatus rv = SECFailure;
int len;
unsigned char *privKeyBytes = NULL;
if (!ecParams) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
len = ecParams->order.len;
privKeyBytes = ec_GenerateRandomPrivateKey(ecParams->order.data, len,
random, randomlen, kmflag);
if (privKeyBytes == NULL) goto cleanup;
/* generate public key */
CHECK_SEC_OK( ec_NewKey(ecParams, privKey, privKeyBytes, len, kmflag) );
cleanup:
if (privKeyBytes) {
PORT_ZFree(privKeyBytes, len * 2);
}
#if EC_DEBUG
printf("EC_NewKey returning %s\n",
(rv == SECSuccess) ? "success" : "failure");
#endif
return rv;
}
/* Validates an EC public key as described in Section 5.2.2 of
* X9.62. The ECDH primitive when used without the cofactor does
* not address small subgroup attacks, which may occur when the
* public key is not valid. These attacks can be prevented by
* validating the public key before using ECDH.
*/
SECStatus
EC_ValidatePublicKey(ECParams *ecParams, SECItem *publicValue, int kmflag)
{
mp_int Px, Py;
ECGroup *group = NULL;
SECStatus rv = SECFailure;
mp_err err = MP_OKAY;
unsigned int len;
if (!ecParams || !publicValue) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
/* NOTE: We only support uncompressed points for now */
len = (ecParams->fieldID.size + 7) >> 3;
if (publicValue->data[0] != EC_POINT_FORM_UNCOMPRESSED) {
PORT_SetError(SEC_ERROR_UNSUPPORTED_EC_POINT_FORM);
return SECFailure;
} else if (publicValue->len != (2 * len + 1)) {
PORT_SetError(SEC_ERROR_BAD_KEY);
return SECFailure;
}
MP_DIGITS(&Px) = 0;
MP_DIGITS(&Py) = 0;
CHECK_MPI_OK( mp_init(&Px, kmflag) );
CHECK_MPI_OK( mp_init(&Py, kmflag) );
/* Initialize Px and Py */
CHECK_MPI_OK( mp_read_unsigned_octets(&Px, publicValue->data + 1, (mp_size) len) );
CHECK_MPI_OK( mp_read_unsigned_octets(&Py, publicValue->data + 1 + len, (mp_size) len) );
/* construct from named params */
group = ECGroup_fromName(ecParams->name, kmflag);
if (group == NULL) {
/*
* ECGroup_fromName fails if ecParams->name is not a valid
* ECCurveName value, or if we run out of memory, or perhaps
* for other reasons. Unfortunately if ecParams->name is a
* valid ECCurveName value, we don't know what the right error
* code should be because ECGroup_fromName doesn't return an
* error code to the caller. Set err to MP_UNDEF because
* that's what ECGroup_fromName uses internally.
*/
if ((ecParams->name <= ECCurve_noName) ||
(ecParams->name >= ECCurve_pastLastCurve)) {
err = MP_BADARG;
} else {
err = MP_UNDEF;
}
goto cleanup;
}
/* validate public point */
if ((err = ECPoint_validate(group, &Px, &Py)) < MP_YES) {
if (err == MP_NO) {
PORT_SetError(SEC_ERROR_BAD_KEY);
rv = SECFailure;
err = MP_OKAY; /* don't change the error code */
}
goto cleanup;
}
rv = SECSuccess;
cleanup:
ECGroup_free(group);
mp_clear(&Px);
mp_clear(&Py);
if (err) {
MP_TO_SEC_ERROR(err);
rv = SECFailure;
}
return rv;
}
/*
** Performs an ECDH key derivation by computing the scalar point
** multiplication of privateValue and publicValue (with or without the
** cofactor) and returns the x-coordinate of the resulting elliptic
** curve point in derived secret. If successful, derivedSecret->data
** is set to the address of the newly allocated buffer containing the
** derived secret, and derivedSecret->len is the size of the secret
** produced. It is the caller's responsibility to free the allocated
** buffer containing the derived secret.
*/
SECStatus
ECDH_Derive(SECItem *publicValue,
ECParams *ecParams,
SECItem *privateValue,
PRBool withCofactor,
SECItem *derivedSecret,
int kmflag)
{
SECStatus rv = SECFailure;
unsigned int len = 0;
SECItem pointQ = {siBuffer, NULL, 0};
mp_int k; /* to hold the private value */
mp_int cofactor;
mp_err err = MP_OKAY;
#if EC_DEBUG
int i;
#endif
if (!publicValue || !ecParams || !privateValue ||
!derivedSecret) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
memset(derivedSecret, 0, sizeof *derivedSecret);
len = (ecParams->fieldID.size + 7) >> 3;
pointQ.len = 2*len + 1;
if ((pointQ.data = PORT_Alloc(2*len + 1, kmflag)) == NULL) goto cleanup;
MP_DIGITS(&k) = 0;
CHECK_MPI_OK( mp_init(&k, kmflag) );
CHECK_MPI_OK( mp_read_unsigned_octets(&k, privateValue->data,
(mp_size) privateValue->len) );
if (withCofactor && (ecParams->cofactor != 1)) {
/* multiply k with the cofactor */
MP_DIGITS(&cofactor) = 0;
CHECK_MPI_OK( mp_init(&cofactor, kmflag) );
mp_set(&cofactor, ecParams->cofactor);
CHECK_MPI_OK( mp_mul(&k, &cofactor, &k) );
}
/* Multiply our private key and peer's public point */
if ((ec_points_mul(ecParams, NULL, &k, publicValue, &pointQ, kmflag) != SECSuccess) ||
ec_point_at_infinity(&pointQ))
goto cleanup;
/* Allocate memory for the derived secret and copy
* the x co-ordinate of pointQ into it.
*/
SECITEM_AllocItem(NULL, derivedSecret, len, kmflag);
memcpy(derivedSecret->data, pointQ.data + 1, len);
rv = SECSuccess;
#if EC_DEBUG
printf("derived_secret:\n");
for (i = 0; i < derivedSecret->len; i++)
printf("%02x:", derivedSecret->data[i]);
printf("\n");
#endif
cleanup:
mp_clear(&k);
if (pointQ.data) {
PORT_ZFree(pointQ.data, 2*len + 1);
}
return rv;
}
/* Computes the ECDSA signature (a concatenation of two values r and s)
* on the digest using the given key and the random value kb (used in
* computing s).
*/
SECStatus
ECDSA_SignDigestWithSeed(ECPrivateKey *key, SECItem *signature,
const SECItem *digest, const unsigned char *kb, const int kblen, int kmflag)
{
SECStatus rv = SECFailure;
mp_int x1;
mp_int d, k; /* private key, random integer */
mp_int r, s; /* tuple (r, s) is the signature */
mp_int n;
mp_err err = MP_OKAY;
ECParams *ecParams = NULL;
SECItem kGpoint = { siBuffer, NULL, 0};
int flen = 0; /* length in bytes of the field size */
unsigned olen; /* length in bytes of the base point order */
#if EC_DEBUG
char mpstr[256];
#endif
/* Initialize MPI integers. */
/* must happen before the first potential call to cleanup */
MP_DIGITS(&x1) = 0;
MP_DIGITS(&d) = 0;
MP_DIGITS(&k) = 0;
MP_DIGITS(&r) = 0;
MP_DIGITS(&s) = 0;
MP_DIGITS(&n) = 0;
/* Check args */
if (!key || !signature || !digest || !kb || (kblen < 0)) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
goto cleanup;
}
ecParams = &(key->ecParams);
flen = (ecParams->fieldID.size + 7) >> 3;
olen = ecParams->order.len;
if (signature->data == NULL) {
/* a call to get the signature length only */
goto finish;
}
if (signature->len < 2*olen) {
PORT_SetError(SEC_ERROR_OUTPUT_LEN);
rv = SECBufferTooSmall;
goto cleanup;
}
CHECK_MPI_OK( mp_init(&x1, kmflag) );
CHECK_MPI_OK( mp_init(&d, kmflag) );
CHECK_MPI_OK( mp_init(&k, kmflag) );
CHECK_MPI_OK( mp_init(&r, kmflag) );
CHECK_MPI_OK( mp_init(&s, kmflag) );
CHECK_MPI_OK( mp_init(&n, kmflag) );
SECITEM_TO_MPINT( ecParams->order, &n );
SECITEM_TO_MPINT( key->privateValue, &d );
CHECK_MPI_OK( mp_read_unsigned_octets(&k, kb, kblen) );
/* Make sure k is in the interval [1, n-1] */
if ((mp_cmp_z(&k) <= 0) || (mp_cmp(&k, &n) >= 0)) {
#if EC_DEBUG
printf("k is outside [1, n-1]\n");
mp_tohex(&k, mpstr);
printf("k : %s \n", mpstr);
mp_tohex(&n, mpstr);
printf("n : %s \n", mpstr);
#endif
PORT_SetError(SEC_ERROR_NEED_RANDOM);
goto cleanup;
}
/*
** ANSI X9.62, Section 5.3.2, Step 2
**
** Compute kG
*/
kGpoint.len = 2*flen + 1;
kGpoint.data = PORT_Alloc(2*flen + 1, kmflag);
if ((kGpoint.data == NULL) ||
(ec_points_mul(ecParams, &k, NULL, NULL, &kGpoint, kmflag)
!= SECSuccess))
goto cleanup;
/*
** ANSI X9.62, Section 5.3.3, Step 1
**
** Extract the x co-ordinate of kG into x1
*/
CHECK_MPI_OK( mp_read_unsigned_octets(&x1, kGpoint.data + 1,
(mp_size) flen) );
/*
** ANSI X9.62, Section 5.3.3, Step 2
**
** r = x1 mod n NOTE: n is the order of the curve
*/
CHECK_MPI_OK( mp_mod(&x1, &n, &r) );
/*
** ANSI X9.62, Section 5.3.3, Step 3
**
** verify r != 0
*/
if (mp_cmp_z(&r) == 0) {
PORT_SetError(SEC_ERROR_NEED_RANDOM);
goto cleanup;
}
/*
** ANSI X9.62, Section 5.3.3, Step 4
**
** s = (k**-1 * (HASH(M) + d*r)) mod n
*/
SECITEM_TO_MPINT(*digest, &s); /* s = HASH(M) */
/* In the definition of EC signing, digests are truncated
* to the length of n in bits.
* (see SEC 1 "Elliptic Curve Digit Signature Algorithm" section 4.1.*/
if (digest->len*8 > (unsigned int)ecParams->fieldID.size) {
mpl_rsh(&s,&s,digest->len*8 - ecParams->fieldID.size);
}
#if EC_DEBUG
mp_todecimal(&n, mpstr);
printf("n : %s (dec)\n", mpstr);
mp_todecimal(&d, mpstr);
printf("d : %s (dec)\n", mpstr);
mp_tohex(&x1, mpstr);
printf("x1: %s\n", mpstr);
mp_todecimal(&s, mpstr);
printf("digest: %s (decimal)\n", mpstr);
mp_todecimal(&r, mpstr);
printf("r : %s (dec)\n", mpstr);
mp_tohex(&r, mpstr);
printf("r : %s\n", mpstr);
#endif
CHECK_MPI_OK( mp_invmod(&k, &n, &k) ); /* k = k**-1 mod n */
CHECK_MPI_OK( mp_mulmod(&d, &r, &n, &d) ); /* d = d * r mod n */
CHECK_MPI_OK( mp_addmod(&s, &d, &n, &s) ); /* s = s + d mod n */
CHECK_MPI_OK( mp_mulmod(&s, &k, &n, &s) ); /* s = s * k mod n */
#if EC_DEBUG
mp_todecimal(&s, mpstr);
printf("s : %s (dec)\n", mpstr);
mp_tohex(&s, mpstr);
printf("s : %s\n", mpstr);
#endif
/*
** ANSI X9.62, Section 5.3.3, Step 5
**
** verify s != 0
*/
if (mp_cmp_z(&s) == 0) {
PORT_SetError(SEC_ERROR_NEED_RANDOM);
goto cleanup;
}
/*
**
** Signature is tuple (r, s)
*/
CHECK_MPI_OK( mp_to_fixlen_octets(&r, signature->data, olen) );
CHECK_MPI_OK( mp_to_fixlen_octets(&s, signature->data + olen, olen) );
finish:
signature->len = 2*olen;
rv = SECSuccess;
err = MP_OKAY;
cleanup:
mp_clear(&x1);
mp_clear(&d);
mp_clear(&k);
mp_clear(&r);
mp_clear(&s);
mp_clear(&n);
if (kGpoint.data) {
PORT_ZFree(kGpoint.data, 2*flen + 1);
}
if (err) {
MP_TO_SEC_ERROR(err);
rv = SECFailure;
}
#if EC_DEBUG
printf("ECDSA signing with seed %s\n",
(rv == SECSuccess) ? "succeeded" : "failed");
#endif
return rv;
}
/*
** Computes the ECDSA signature on the digest using the given key
** and a random seed.
*/
SECStatus
ECDSA_SignDigest(ECPrivateKey *key, SECItem *signature, const SECItem *digest,
const unsigned char* random, int randomLen, int kmflag)
{
SECStatus rv = SECFailure;
int len;
unsigned char *kBytes= NULL;
if (!key) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
/* Generate random value k */
len = key->ecParams.order.len;
kBytes = ec_GenerateRandomPrivateKey(key->ecParams.order.data, len,
random, randomLen, kmflag);
if (kBytes == NULL) goto cleanup;
/* Generate ECDSA signature with the specified k value */
rv = ECDSA_SignDigestWithSeed(key, signature, digest, kBytes, len, kmflag);
cleanup:
if (kBytes) {
PORT_ZFree(kBytes, len * 2);
}
#if EC_DEBUG
printf("ECDSA signing %s\n",
(rv == SECSuccess) ? "succeeded" : "failed");
#endif
return rv;
}
/*
** Checks the signature on the given digest using the key provided.
*/
SECStatus
ECDSA_VerifyDigest(ECPublicKey *key, const SECItem *signature,
const SECItem *digest, int kmflag)
{
SECStatus rv = SECFailure;
mp_int r_, s_; /* tuple (r', s') is received signature) */
mp_int c, u1, u2, v; /* intermediate values used in verification */
mp_int x1;
mp_int n;
mp_err err = MP_OKAY;
ECParams *ecParams = NULL;
SECItem pointC = { siBuffer, NULL, 0 };
int slen; /* length in bytes of a half signature (r or s) */
int flen; /* length in bytes of the field size */
unsigned olen; /* length in bytes of the base point order */
#if EC_DEBUG
char mpstr[256];
printf("ECDSA verification called\n");
#endif
/* Initialize MPI integers. */
/* must happen before the first potential call to cleanup */
MP_DIGITS(&r_) = 0;
MP_DIGITS(&s_) = 0;
MP_DIGITS(&c) = 0;
MP_DIGITS(&u1) = 0;
MP_DIGITS(&u2) = 0;
MP_DIGITS(&x1) = 0;
MP_DIGITS(&v) = 0;
MP_DIGITS(&n) = 0;
/* Check args */
if (!key || !signature || !digest) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
goto cleanup;
}
ecParams = &(key->ecParams);
flen = (ecParams->fieldID.size + 7) >> 3;
olen = ecParams->order.len;
if (signature->len == 0 || signature->len%2 != 0 ||
signature->len > 2*olen) {
PORT_SetError(SEC_ERROR_INPUT_LEN);
goto cleanup;
}
slen = signature->len/2;
SECITEM_AllocItem(NULL, &pointC, 2*flen + 1, kmflag);
if (pointC.data == NULL)
goto cleanup;
CHECK_MPI_OK( mp_init(&r_, kmflag) );
CHECK_MPI_OK( mp_init(&s_, kmflag) );
CHECK_MPI_OK( mp_init(&c, kmflag) );
CHECK_MPI_OK( mp_init(&u1, kmflag) );
CHECK_MPI_OK( mp_init(&u2, kmflag) );
CHECK_MPI_OK( mp_init(&x1, kmflag) );
CHECK_MPI_OK( mp_init(&v, kmflag) );
CHECK_MPI_OK( mp_init(&n, kmflag) );
/*
** Convert received signature (r', s') into MPI integers.
*/
CHECK_MPI_OK( mp_read_unsigned_octets(&r_, signature->data, slen) );
CHECK_MPI_OK( mp_read_unsigned_octets(&s_, signature->data + slen, slen) );
/*
** ANSI X9.62, Section 5.4.2, Steps 1 and 2
**
** Verify that 0 < r' < n and 0 < s' < n
*/
SECITEM_TO_MPINT(ecParams->order, &n);
if (mp_cmp_z(&r_) <= 0 || mp_cmp_z(&s_) <= 0 ||
mp_cmp(&r_, &n) >= 0 || mp_cmp(&s_, &n) >= 0) {
PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
goto cleanup; /* will return rv == SECFailure */
}
/*
** ANSI X9.62, Section 5.4.2, Step 3
**
** c = (s')**-1 mod n
*/
CHECK_MPI_OK( mp_invmod(&s_, &n, &c) ); /* c = (s')**-1 mod n */
/*
** ANSI X9.62, Section 5.4.2, Step 4
**
** u1 = ((HASH(M')) * c) mod n
*/
SECITEM_TO_MPINT(*digest, &u1); /* u1 = HASH(M) */
/* In the definition of EC signing, digests are truncated
* to the length of n in bits.
* (see SEC 1 "Elliptic Curve Digit Signature Algorithm" section 4.1.*/
/* u1 = HASH(M') */
if (digest->len*8 > (unsigned int)ecParams->fieldID.size) {
mpl_rsh(&u1,&u1,digest->len*8- ecParams->fieldID.size);
}
#if EC_DEBUG
mp_todecimal(&r_, mpstr);
printf("r_: %s (dec)\n", mpstr);
mp_todecimal(&s_, mpstr);
printf("s_: %s (dec)\n", mpstr);
mp_todecimal(&c, mpstr);
printf("c : %s (dec)\n", mpstr);
mp_todecimal(&u1, mpstr);
printf("digest: %s (dec)\n", mpstr);
#endif
CHECK_MPI_OK( mp_mulmod(&u1, &c, &n, &u1) ); /* u1 = u1 * c mod n */
/*
** ANSI X9.62, Section 5.4.2, Step 4
**
** u2 = ((r') * c) mod n
*/
CHECK_MPI_OK( mp_mulmod(&r_, &c, &n, &u2) );
/*
** ANSI X9.62, Section 5.4.3, Step 1
**
** Compute u1*G + u2*Q
** Here, A = u1.G B = u2.Q and C = A + B
** If the result, C, is the point at infinity, reject the signature
*/
if (ec_points_mul(ecParams, &u1, &u2, &key->publicValue, &pointC, kmflag)
!= SECSuccess) {
rv = SECFailure;
goto cleanup;
}
if (ec_point_at_infinity(&pointC)) {
PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
rv = SECFailure;
goto cleanup;
}
CHECK_MPI_OK( mp_read_unsigned_octets(&x1, pointC.data + 1, flen) );
/*
** ANSI X9.62, Section 5.4.4, Step 2
**
** v = x1 mod n
*/
CHECK_MPI_OK( mp_mod(&x1, &n, &v) );
#if EC_DEBUG
mp_todecimal(&r_, mpstr);
printf("r_: %s (dec)\n", mpstr);
mp_todecimal(&v, mpstr);
printf("v : %s (dec)\n", mpstr);
#endif
/*
** ANSI X9.62, Section 5.4.4, Step 3
**
** Verification: v == r'
*/
if (mp_cmp(&v, &r_)) {
PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
rv = SECFailure; /* Signature failed to verify. */
} else {
rv = SECSuccess; /* Signature verified. */
}
#if EC_DEBUG
mp_todecimal(&u1, mpstr);
printf("u1: %s (dec)\n", mpstr);
mp_todecimal(&u2, mpstr);
printf("u2: %s (dec)\n", mpstr);
mp_tohex(&x1, mpstr);
printf("x1: %s\n", mpstr);
mp_todecimal(&v, mpstr);
printf("v : %s (dec)\n", mpstr);
#endif
cleanup:
mp_clear(&r_);
mp_clear(&s_);
mp_clear(&c);
mp_clear(&u1);
mp_clear(&u2);
mp_clear(&x1);
mp_clear(&v);
mp_clear(&n);
if (pointC.data) SECITEM_FreeItem(&pointC, PR_FALSE);
if (err) {
MP_TO_SEC_ERROR(err);
rv = SECFailure;
}
#if EC_DEBUG
printf("ECDSA verification %s\n",
(rv == SECSuccess) ? "succeeded" : "failed");
#endif
return rv;
}
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