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gecko-dev/security/nss/lib/freebl/dsa.c

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18 KiB
C
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/*
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifdef FREEBL_NO_DEPEND
#include "stubs.h"
#endif
#include "prerror.h"
#include "secerr.h"
#include "prtypes.h"
#include "prinit.h"
#include "blapi.h"
#include "nssilock.h"
#include "secitem.h"
#include "blapi.h"
#include "mpi.h"
#include "secmpi.h"
#include "pqg.h"
/* XXX to be replaced by define in blapit.h */
#define NSS_FREEBL_DSA_DEFAULT_CHUNKSIZE 2048
/*
* FIPS 186-2 requires result from random output to be reduced mod q when
* generating random numbers for DSA.
*
* Input: w, 2*qLen bytes
* q, qLen bytes
* Output: xj, qLen bytes
*/
static SECStatus
fips186Change_ReduceModQForDSA(const PRUint8 *w, const PRUint8 *q,
unsigned int qLen, PRUint8 * xj)
{
mp_int W, Q, Xj;
mp_err err;
SECStatus rv = SECSuccess;
/* Initialize MPI integers. */
MP_DIGITS(&W) = 0;
MP_DIGITS(&Q) = 0;
MP_DIGITS(&Xj) = 0;
CHECK_MPI_OK( mp_init(&W) );
CHECK_MPI_OK( mp_init(&Q) );
CHECK_MPI_OK( mp_init(&Xj) );
/*
* Convert input arguments into MPI integers.
*/
CHECK_MPI_OK( mp_read_unsigned_octets(&W, w, 2*qLen) );
CHECK_MPI_OK( mp_read_unsigned_octets(&Q, q, qLen) );
/*
* Algorithm 1 of FIPS 186-2 Change Notice 1, Step 3.3
*
* xj = (w0 || w1) mod q
*/
CHECK_MPI_OK( mp_mod(&W, &Q, &Xj) );
CHECK_MPI_OK( mp_to_fixlen_octets(&Xj, xj, qLen) );
cleanup:
mp_clear(&W);
mp_clear(&Q);
mp_clear(&Xj);
if (err) {
MP_TO_SEC_ERROR(err);
rv = SECFailure;
}
return rv;
}
/*
* FIPS 186-2 requires result from random output to be reduced mod q when
* generating random numbers for DSA.
*/
SECStatus
FIPS186Change_ReduceModQForDSA(const unsigned char *w,
const unsigned char *q,
unsigned char *xj) {
return fips186Change_ReduceModQForDSA(w, q, DSA1_SUBPRIME_LEN, xj);
}
/*
* The core of Algorithm 1 of FIPS 186-2 Change Notice 1.
*
* We no longer support FIPS 186-2 RNG. This function was exported
* for power-up self tests and FIPS tests. Keep this stub, which fails,
* to prevent crashes, but also to signal to test code that FIPS 186-2
* RNG is no longer supported.
*/
SECStatus
FIPS186Change_GenerateX(PRUint8 *XKEY, const PRUint8 *XSEEDj,
PRUint8 *x_j)
{
PORT_SetError(PR_NOT_IMPLEMENTED_ERROR);
return SECFailure;
}
/*
* Specialized RNG for DSA
*
* As per Algorithm 1 of FIPS 186-2 Change Notice 1, in step 3.3 the value
* Xj should be reduced mod q, a 160-bit prime number. Since this parameter
* is only meaningful in the context of DSA, the above RNG functions
* were implemented without it. They are re-implemented below for use
* with DSA.
*/
/*
** Generate some random bytes, using the global random number generator
** object. In DSA mode, so there is a q.
*/
static SECStatus
dsa_GenerateGlobalRandomBytes(const SECItem * qItem, PRUint8 * dest,
unsigned int * destLen, unsigned int maxDestLen)
{
SECStatus rv;
SECItem w;
const PRUint8 * q = qItem->data;
unsigned int qLen = qItem->len;
if (*q == 0) {
++q;
--qLen;
}
if (maxDestLen < qLen) {
/* This condition can occur when DSA_SignDigest is passed a group
with a subprime that is larger than DSA_MAX_SUBPRIME_LEN. */
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
w.data = NULL; /* otherwise SECITEM_AllocItem asserts */
if (!SECITEM_AllocItem(NULL, &w, 2*qLen)) {
return SECFailure;
}
*destLen = qLen;
rv = RNG_GenerateGlobalRandomBytes(w.data, w.len);
if (rv == SECSuccess) {
rv = fips186Change_ReduceModQForDSA(w.data, q, qLen, dest);
}
SECITEM_FreeItem(&w, PR_FALSE);
return rv;
}
static void translate_mpi_error(mp_err err)
{
MP_TO_SEC_ERROR(err);
}
static SECStatus
dsa_NewKeyExtended(const PQGParams *params, const SECItem * seed,
DSAPrivateKey **privKey)
{
mp_int p, g;
mp_int x, y;
mp_err err;
PLArenaPool *arena;
DSAPrivateKey *key;
/* Check args. */
if (!params || !privKey || !seed || !seed->data) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
/* Initialize an arena for the DSA key. */
arena = PORT_NewArena(NSS_FREEBL_DSA_DEFAULT_CHUNKSIZE);
if (!arena) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
return SECFailure;
}
key = (DSAPrivateKey *)PORT_ArenaZAlloc(arena, sizeof(DSAPrivateKey));
if (!key) {
PORT_SetError(SEC_ERROR_NO_MEMORY);
PORT_FreeArena(arena, PR_TRUE);
return SECFailure;
}
key->params.arena = arena;
/* Initialize MPI integers. */
MP_DIGITS(&p) = 0;
MP_DIGITS(&g) = 0;
MP_DIGITS(&x) = 0;
MP_DIGITS(&y) = 0;
CHECK_MPI_OK( mp_init(&p) );
CHECK_MPI_OK( mp_init(&g) );
CHECK_MPI_OK( mp_init(&x) );
CHECK_MPI_OK( mp_init(&y) );
/* Copy over the PQG params */
CHECK_MPI_OK( SECITEM_CopyItem(arena, &key->params.prime,
&params->prime) );
CHECK_MPI_OK( SECITEM_CopyItem(arena, &key->params.subPrime,
&params->subPrime) );
CHECK_MPI_OK( SECITEM_CopyItem(arena, &key->params.base, &params->base) );
/* Convert stored p, g, and received x into MPI integers. */
SECITEM_TO_MPINT(params->prime, &p);
SECITEM_TO_MPINT(params->base, &g);
OCTETS_TO_MPINT(seed->data, &x, seed->len);
/* Store x in private key */
SECITEM_AllocItem(arena, &key->privateValue, seed->len);
PORT_Memcpy(key->privateValue.data, seed->data, seed->len);
/* Compute public key y = g**x mod p */
CHECK_MPI_OK( mp_exptmod(&g, &x, &p, &y) );
/* Store y in public key */
MPINT_TO_SECITEM(&y, &key->publicValue, arena);
*privKey = key;
key = NULL;
cleanup:
mp_clear(&p);
mp_clear(&g);
mp_clear(&x);
mp_clear(&y);
if (key)
PORT_FreeArena(key->params.arena, PR_TRUE);
if (err) {
translate_mpi_error(err);
return SECFailure;
}
return SECSuccess;
}
SECStatus
DSA_NewRandom(PLArenaPool * arena, const SECItem * q, SECItem * seed)
{
int retries = 10;
unsigned int i;
PRBool good;
if (q == NULL || q->data == NULL || q->len == 0 ||
(q->data[0] == 0 && q->len == 1)) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
if (!SECITEM_AllocItem(arena, seed, q->len)) {
return SECFailure;
}
do {
/* Generate seed bytes for x according to FIPS 186-1 appendix 3 */
if (dsa_GenerateGlobalRandomBytes(q, seed->data, &seed->len,
seed->len)) {
goto loser;
}
/* Disallow values of 0 and 1 for x. */
good = PR_FALSE;
for (i = 0; i < seed->len-1; i++) {
if (seed->data[i] != 0) {
good = PR_TRUE;
break;
}
}
if (!good && seed->data[i] > 1) {
good = PR_TRUE;
}
} while (!good && --retries > 0);
if (!good) {
PORT_SetError(SEC_ERROR_NEED_RANDOM);
loser: if (arena != NULL) {
SECITEM_FreeItem(seed, PR_FALSE);
}
return SECFailure;
}
return SECSuccess;
}
/*
** Generate and return a new DSA public and private key pair,
** both of which are encoded into a single DSAPrivateKey struct.
** "params" is a pointer to the PQG parameters for the domain
** Uses a random seed.
*/
SECStatus
DSA_NewKey(const PQGParams *params, DSAPrivateKey **privKey)
{
SECItem seed;
SECStatus rv;
rv = PQG_Check(params);
if (rv != SECSuccess) {
return rv;
}
seed.data = NULL;
rv = DSA_NewRandom(NULL, &params->subPrime, &seed);
if (rv == SECSuccess) {
if (seed.len != PQG_GetLength(&params->subPrime)) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
rv = SECFailure;
} else {
rv = dsa_NewKeyExtended(params, &seed, privKey);
}
}
SECITEM_FreeItem(&seed, PR_FALSE);
return rv;
}
/* For FIPS compliance testing. Seed must be exactly the size of subPrime */
SECStatus
DSA_NewKeyFromSeed(const PQGParams *params,
const unsigned char *seed,
DSAPrivateKey **privKey)
{
SECItem seedItem;
seedItem.data = (unsigned char*) seed;
seedItem.len = PQG_GetLength(&params->subPrime);
return dsa_NewKeyExtended(params, &seedItem, privKey);
}
static SECStatus
dsa_SignDigest(DSAPrivateKey *key, SECItem *signature, const SECItem *digest,
const unsigned char *kb)
{
mp_int p, q, g; /* PQG parameters */
mp_int x, k; /* private key & pseudo-random integer */
mp_int r, s; /* tuple (r, s) is signature) */
mp_err err = MP_OKAY;
SECStatus rv = SECSuccess;
unsigned int dsa_subprime_len, dsa_signature_len, offset;
SECItem localDigest;
unsigned char localDigestData[DSA_MAX_SUBPRIME_LEN];
/* FIPS-compliance dictates that digest is a SHA hash. */
/* Check args. */
if (!key || !signature || !digest) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
dsa_subprime_len = PQG_GetLength(&key->params.subPrime);
dsa_signature_len = dsa_subprime_len*2;
if ((signature->len < dsa_signature_len) ||
(digest->len > HASH_LENGTH_MAX) ||
(digest->len < SHA1_LENGTH)) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
/* DSA accepts digests not equal to dsa_subprime_len, if the
* digests are greater, then they are truncated to the size of
* dsa_subprime_len, using the left most bits. If they are less
* then they are padded on the left.*/
PORT_Memset(localDigestData, 0, dsa_subprime_len);
offset = (digest->len < dsa_subprime_len) ?
(dsa_subprime_len - digest->len) : 0;
PORT_Memcpy(localDigestData+offset, digest->data,
dsa_subprime_len - offset);
localDigest.data = localDigestData;
localDigest.len = dsa_subprime_len;
/* Initialize MPI integers. */
MP_DIGITS(&p) = 0;
MP_DIGITS(&q) = 0;
MP_DIGITS(&g) = 0;
MP_DIGITS(&x) = 0;
MP_DIGITS(&k) = 0;
MP_DIGITS(&r) = 0;
MP_DIGITS(&s) = 0;
CHECK_MPI_OK( mp_init(&p) );
CHECK_MPI_OK( mp_init(&q) );
CHECK_MPI_OK( mp_init(&g) );
CHECK_MPI_OK( mp_init(&x) );
CHECK_MPI_OK( mp_init(&k) );
CHECK_MPI_OK( mp_init(&r) );
CHECK_MPI_OK( mp_init(&s) );
/*
** Convert stored PQG and private key into MPI integers.
*/
SECITEM_TO_MPINT(key->params.prime, &p);
SECITEM_TO_MPINT(key->params.subPrime, &q);
SECITEM_TO_MPINT(key->params.base, &g);
SECITEM_TO_MPINT(key->privateValue, &x);
OCTETS_TO_MPINT(kb, &k, dsa_subprime_len);
/*
** FIPS 186-1, Section 5, Step 1
**
** r = (g**k mod p) mod q
*/
CHECK_MPI_OK( mp_exptmod(&g, &k, &p, &r) ); /* r = g**k mod p */
CHECK_MPI_OK( mp_mod(&r, &q, &r) ); /* r = r mod q */
/*
** FIPS 186-1, Section 5, Step 2
**
** s = (k**-1 * (HASH(M) + x*r)) mod q
*/
SECITEM_TO_MPINT(localDigest, &s); /* s = HASH(M) */
CHECK_MPI_OK( mp_invmod(&k, &q, &k) ); /* k = k**-1 mod q */
CHECK_MPI_OK( mp_mulmod(&x, &r, &q, &x) ); /* x = x * r mod q */
CHECK_MPI_OK( mp_addmod(&s, &x, &q, &s) ); /* s = s + x mod q */
CHECK_MPI_OK( mp_mulmod(&s, &k, &q, &s) ); /* s = s * k mod q */
/*
** verify r != 0 and s != 0
** mentioned as optional in FIPS 186-1.
*/
if (mp_cmp_z(&r) == 0 || mp_cmp_z(&s) == 0) {
PORT_SetError(SEC_ERROR_NEED_RANDOM);
rv = SECFailure;
goto cleanup;
}
/*
** Step 4
**
** Signature is tuple (r, s)
*/
err = mp_to_fixlen_octets(&r, signature->data, dsa_subprime_len);
if (err < 0) goto cleanup;
err = mp_to_fixlen_octets(&s, signature->data + dsa_subprime_len,
dsa_subprime_len);
if (err < 0) goto cleanup;
err = MP_OKAY;
signature->len = dsa_signature_len;
cleanup:
PORT_Memset(localDigestData, 0, DSA_MAX_SUBPRIME_LEN);
mp_clear(&p);
mp_clear(&q);
mp_clear(&g);
mp_clear(&x);
mp_clear(&k);
mp_clear(&r);
mp_clear(&s);
if (err) {
translate_mpi_error(err);
rv = SECFailure;
}
return rv;
}
/* signature is caller-supplied buffer of at least 40 bytes.
** On input, signature->len == size of buffer to hold signature.
** digest->len == size of digest.
** On output, signature->len == size of signature in buffer.
** Uses a random seed.
*/
SECStatus
DSA_SignDigest(DSAPrivateKey *key, SECItem *signature, const SECItem *digest)
{
SECStatus rv;
int retries = 10;
unsigned char kSeed[DSA_MAX_SUBPRIME_LEN];
unsigned int kSeedLen = 0;
unsigned int i;
unsigned int dsa_subprime_len = PQG_GetLength(&key->params.subPrime);
PRBool good;
PORT_SetError(0);
do {
rv = dsa_GenerateGlobalRandomBytes(&key->params.subPrime,
kSeed, &kSeedLen, sizeof kSeed);
if (rv != SECSuccess)
break;
if (kSeedLen != dsa_subprime_len) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
rv = SECFailure;
break;
}
/* Disallow a value of 0 for k. */
good = PR_FALSE;
for (i = 0; i < kSeedLen; i++) {
if (kSeed[i] != 0) {
good = PR_TRUE;
break;
}
}
if (!good) {
PORT_SetError(SEC_ERROR_NEED_RANDOM);
rv = SECFailure;
continue;
}
rv = dsa_SignDigest(key, signature, digest, kSeed);
} while (rv != SECSuccess && PORT_GetError() == SEC_ERROR_NEED_RANDOM &&
--retries > 0);
return rv;
}
/* For FIPS compliance testing. Seed must be exactly 20 bytes. */
SECStatus
DSA_SignDigestWithSeed(DSAPrivateKey * key,
SECItem * signature,
const SECItem * digest,
const unsigned char * seed)
{
SECStatus rv;
rv = dsa_SignDigest(key, signature, digest, seed);
return rv;
}
/* signature is caller-supplied buffer of at least 20 bytes.
** On input, signature->len == size of buffer to hold signature.
** digest->len == size of digest.
*/
SECStatus
DSA_VerifyDigest(DSAPublicKey *key, const SECItem *signature,
const SECItem *digest)
{
/* FIPS-compliance dictates that digest is a SHA hash. */
mp_int p, q, g; /* PQG parameters */
mp_int r_, s_; /* tuple (r', s') is received signature) */
mp_int u1, u2, v, w; /* intermediate values used in verification */
mp_int y; /* public key */
mp_err err;
int dsa_subprime_len, dsa_signature_len, offset;
SECItem localDigest;
unsigned char localDigestData[DSA_MAX_SUBPRIME_LEN];
SECStatus verified = SECFailure;
/* Check args. */
if (!key || !signature || !digest ) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
dsa_subprime_len = PQG_GetLength(&key->params.subPrime);
dsa_signature_len = dsa_subprime_len*2;
if ((signature->len != dsa_signature_len) ||
(digest->len > HASH_LENGTH_MAX) ||
(digest->len < SHA1_LENGTH)) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
/* DSA accepts digests not equal to dsa_subprime_len, if the
* digests are greater, than they are truncated to the size of
* dsa_subprime_len, using the left most bits. If they are less
* then they are padded on the left.*/
PORT_Memset(localDigestData, 0, dsa_subprime_len);
offset = (digest->len < dsa_subprime_len) ?
(dsa_subprime_len - digest->len) : 0;
PORT_Memcpy(localDigestData+offset, digest->data,
dsa_subprime_len - offset);
localDigest.data = localDigestData;
localDigest.len = dsa_subprime_len;
/* Initialize MPI integers. */
MP_DIGITS(&p) = 0;
MP_DIGITS(&q) = 0;
MP_DIGITS(&g) = 0;
MP_DIGITS(&y) = 0;
MP_DIGITS(&r_) = 0;
MP_DIGITS(&s_) = 0;
MP_DIGITS(&u1) = 0;
MP_DIGITS(&u2) = 0;
MP_DIGITS(&v) = 0;
MP_DIGITS(&w) = 0;
CHECK_MPI_OK( mp_init(&p) );
CHECK_MPI_OK( mp_init(&q) );
CHECK_MPI_OK( mp_init(&g) );
CHECK_MPI_OK( mp_init(&y) );
CHECK_MPI_OK( mp_init(&r_) );
CHECK_MPI_OK( mp_init(&s_) );
CHECK_MPI_OK( mp_init(&u1) );
CHECK_MPI_OK( mp_init(&u2) );
CHECK_MPI_OK( mp_init(&v) );
CHECK_MPI_OK( mp_init(&w) );
/*
** Convert stored PQG and public key into MPI integers.
*/
SECITEM_TO_MPINT(key->params.prime, &p);
SECITEM_TO_MPINT(key->params.subPrime, &q);
SECITEM_TO_MPINT(key->params.base, &g);
SECITEM_TO_MPINT(key->publicValue, &y);
/*
** Convert received signature (r', s') into MPI integers.
*/
OCTETS_TO_MPINT(signature->data, &r_, dsa_subprime_len);
OCTETS_TO_MPINT(signature->data + dsa_subprime_len, &s_, dsa_subprime_len);
/*
** Verify that 0 < r' < q and 0 < s' < q
*/
if (mp_cmp_z(&r_) <= 0 || mp_cmp_z(&s_) <= 0 ||
mp_cmp(&r_, &q) >= 0 || mp_cmp(&s_, &q) >= 0) {
/* err is zero here. */
PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
goto cleanup; /* will return verified == SECFailure */
}
/*
** FIPS 186-1, Section 6, Step 1
**
** w = (s')**-1 mod q
*/
CHECK_MPI_OK( mp_invmod(&s_, &q, &w) ); /* w = (s')**-1 mod q */
/*
** FIPS 186-1, Section 6, Step 2
**
** u1 = ((Hash(M')) * w) mod q
*/
SECITEM_TO_MPINT(localDigest, &u1); /* u1 = HASH(M') */
CHECK_MPI_OK( mp_mulmod(&u1, &w, &q, &u1) ); /* u1 = u1 * w mod q */
/*
** FIPS 186-1, Section 6, Step 3
**
** u2 = ((r') * w) mod q
*/
CHECK_MPI_OK( mp_mulmod(&r_, &w, &q, &u2) );
/*
** FIPS 186-1, Section 6, Step 4
**
** v = ((g**u1 * y**u2) mod p) mod q
*/
CHECK_MPI_OK( mp_exptmod(&g, &u1, &p, &g) ); /* g = g**u1 mod p */
CHECK_MPI_OK( mp_exptmod(&y, &u2, &p, &y) ); /* y = y**u2 mod p */
CHECK_MPI_OK( mp_mulmod(&g, &y, &p, &v) ); /* v = g * y mod p */
CHECK_MPI_OK( mp_mod(&v, &q, &v) ); /* v = v mod q */
/*
** Verification: v == r'
*/
if (mp_cmp(&v, &r_)) {
PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
verified = SECFailure; /* Signature failed to verify. */
} else {
verified = SECSuccess; /* Signature verified. */
}
cleanup:
mp_clear(&p);
mp_clear(&q);
mp_clear(&g);
mp_clear(&y);
mp_clear(&r_);
mp_clear(&s_);
mp_clear(&u1);
mp_clear(&u2);
mp_clear(&v);
mp_clear(&w);
if (err) {
translate_mpi_error(err);
}
return verified;
}
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