mirror/openssl
2
0
Fork 0
mirror of https://github.com/openssl/openssl.git synced 2024-12-03 05:41:46 +08:00
Code Issues Packages Projects Releases Wiki Activity
22b858a888
openssl/crypto/dh/dh_key.c
Pauli ada66e78ef Deprecate the low level Diffie-Hellman functions. 
Use of the low level DH functions has been informally discouraged for a
long time.  We now formally deprecate them.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11024)
2020-02-20 19:04:57 +10:00

379 lines
9.6 KiB
C
Raw Blame History

/*
* Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* DH low level APIs are deprecated for public use, but still ok for
* internal use.
*/
#include "internal/deprecated.h"
#include <stdio.h>
#include "internal/cryptlib.h"
#include "dh_local.h"
#include "crypto/bn.h"
#include "crypto/dh.h"
static int generate_key(DH *dh);
static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
const BIGNUM *a, const BIGNUM *p,
const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
static int dh_init(DH *dh);
static int dh_finish(DH *dh);
static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
{
BN_CTX *ctx = NULL;
BN_MONT_CTX *mont = NULL;
BIGNUM *tmp;
int ret = -1;
#ifndef FIPS_MODE
int check_result;
#endif
if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS) {
DHerr(0, DH_R_MODULUS_TOO_LARGE);
goto err;
}
if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
DHerr(0, DH_R_MODULUS_TOO_SMALL);
return 0;
}
ctx = BN_CTX_new_ex(dh->libctx);
if (ctx == NULL)
goto err;
BN_CTX_start(ctx);
tmp = BN_CTX_get(ctx);
if (tmp == NULL)
goto err;
if (dh->priv_key == NULL) {
DHerr(0, DH_R_NO_PRIVATE_VALUE);
goto err;
}
if (dh->flags & DH_FLAG_CACHE_MONT_P) {
mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
dh->lock, dh->params.p, ctx);
BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
if (!mont)
goto err;
}
/* TODO(3.0) : Solve in a PR related to Key validation for DH */
#ifndef FIPS_MODE
if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) {
DHerr(0, DH_R_INVALID_PUBKEY);
goto err;
}
#endif
if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->params.p, ctx,
mont)) {
DHerr(0, ERR_R_BN_LIB);
goto err;
}
ret = BN_bn2bin(tmp, key);
err:
BN_CTX_end(ctx);
BN_CTX_free(ctx);
return ret;
}
int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
{
#ifdef FIPS_MODE
return compute_key(key, pub_key, dh);
#else
return dh->meth->compute_key(key, pub_key, dh);
#endif
}
int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh)
{
int rv, pad;
#ifdef FIPS_MODE
rv = compute_key(key, pub_key, dh);
#else
rv = dh->meth->compute_key(key, pub_key, dh);
#endif
if (rv <= 0)
return rv;
pad = BN_num_bytes(dh->params.p) - rv;
if (pad > 0) {
memmove(key + pad, key, rv);
memset(key, 0, pad);
}
return rv + pad;
}
static DH_METHOD dh_ossl = {
"OpenSSL DH Method",
generate_key,
compute_key,
dh_bn_mod_exp,
dh_init,
dh_finish,
DH_FLAG_FIPS_METHOD,
NULL,
NULL
};
static const DH_METHOD *default_DH_method = &dh_ossl;
const DH_METHOD *DH_OpenSSL(void)
{
return &dh_ossl;
}
const DH_METHOD *DH_get_default_method(void)
{
return default_DH_method;
}
static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
const BIGNUM *a, const BIGNUM *p,
const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
{
return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
}
static int dh_init(DH *dh)
{
dh->flags |= DH_FLAG_CACHE_MONT_P;
ffc_params_init(&dh->params);
dh->dirty_cnt++;
return 1;
}
static int dh_finish(DH *dh)
{
BN_MONT_CTX_free(dh->method_mont_p);
return 1;
}
#ifndef FIPS_MODE
void DH_set_default_method(const DH_METHOD *meth)
{
default_DH_method = meth;
}
#endif /* FIPS_MODE */
int DH_generate_key(DH *dh)
{
#ifdef FIPS_MODE
return generate_key(dh);
#else
return dh->meth->generate_key(dh);
#endif
}
int dh_generate_public_key(BN_CTX *ctx, DH *dh, const BIGNUM *priv_key,
BIGNUM *pub_key)
{
int ret = 0;
BIGNUM *prk = BN_new();
BN_MONT_CTX *mont = NULL;
if (prk == NULL)
return 0;
if (dh->flags & DH_FLAG_CACHE_MONT_P) {
mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
dh->lock, dh->params.p, ctx);
if (mont == NULL)
goto err;
}
BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
/* pub_key = g^priv_key mod p */
if (!dh->meth->bn_mod_exp(dh, pub_key, dh->params.g, prk, dh->params.p,
ctx, mont))
goto err;
ret = 1;
err:
BN_clear_free(prk);
return ret;
}
static int generate_key(DH *dh)
{
int ok = 0;
int generate_new_key = 0;
#ifndef FIPS_MODE
unsigned l;
#endif
BN_CTX *ctx = NULL;
BIGNUM *pub_key = NULL, *priv_key = NULL;
if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS) {
DHerr(0, DH_R_MODULUS_TOO_LARGE);
return 0;
}
if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
DHerr(0, DH_R_MODULUS_TOO_SMALL);
return 0;
}
ctx = BN_CTX_new_ex(dh->libctx);
if (ctx == NULL)
goto err;
if (dh->priv_key == NULL) {
priv_key = BN_secure_new();
if (priv_key == NULL)
goto err;
generate_new_key = 1;
} else {
priv_key = dh->priv_key;
}
if (dh->pub_key == NULL) {
pub_key = BN_new();
if (pub_key == NULL)
goto err;
} else {
pub_key = dh->pub_key;
}
if (generate_new_key) {
/* Is it an approved safe prime ?*/
if (DH_get_nid(dh) != NID_undef) {
/*
* The safe prime group code sets N = 2*s
* (where s = max security strength supported).
* N = dh->length (N = maximum bit length of private key)
*/
if (dh->length == 0
|| dh->params.q == NULL
|| dh->length > BN_num_bits(dh->params.q))
goto err;
if (!ffc_generate_private_key(ctx, &dh->params, dh->length,
dh->length / 2, priv_key))
goto err;
} else {
#ifdef FIPS_MODE
if (dh->params.q == NULL)
goto err;
#else
if (dh->params.q == NULL) {
/* secret exponent length */
l = dh->length ? dh->length : BN_num_bits(dh->params.p) - 1;
if (!BN_priv_rand_ex(priv_key, l, BN_RAND_TOP_ONE,
BN_RAND_BOTTOM_ANY, ctx))
goto err;
/*
* We handle just one known case where g is a quadratic non-residue:
* for g = 2: p % 8 == 3
*/
if (BN_is_word(dh->params.g, DH_GENERATOR_2)
&& !BN_is_bit_set(dh->params.p, 2)) {
/* clear bit 0, since it won't be a secret anyway */
if (!BN_clear_bit(priv_key, 0))
goto err;
}
} else
#endif
{
/*
* For FFC FIPS 186-4 keygen
* security strength s = 112,
* Max Private key size N = len(q)
*/
if (!ffc_generate_private_key(ctx, &dh->params,
BN_num_bits(dh->params.q), 112,
priv_key))
goto err;
}
}
}
if (!dh_generate_public_key(ctx, dh, priv_key, pub_key))
goto err;
dh->pub_key = pub_key;
dh->priv_key = priv_key;
dh->dirty_cnt++;
ok = 1;
err:
if (ok != 1)
DHerr(0, ERR_R_BN_LIB);
if (pub_key != dh->pub_key)
BN_free(pub_key);
if (priv_key != dh->priv_key)
BN_free(priv_key);
BN_CTX_free(ctx);
return ok;
}
int dh_buf2key(DH *dh, const unsigned char *buf, size_t len)
{
int err_reason = DH_R_BN_ERROR;
BIGNUM *pubkey = NULL;
const BIGNUM *p;
size_t p_size;
if ((pubkey = BN_bin2bn(buf, len, NULL)) == NULL)
goto err;
DH_get0_pqg(dh, &p, NULL, NULL);
if (p == NULL || (p_size = BN_num_bytes(p)) == 0) {
err_reason = DH_R_NO_PARAMETERS_SET;
goto err;
}
/*
* As per Section 4.2.8.1 of RFC 8446 fail if DHE's
* public key is of size not equal to size of p
*/
if (BN_is_zero(pubkey) || p_size != len) {
err_reason = DH_R_INVALID_PUBKEY;
goto err;
}
if (DH_set0_key(dh, pubkey, NULL) != 1)
goto err;
return 1;
err:
DHerr(DH_F_DH_BUF2KEY, err_reason);
BN_free(pubkey);
return 0;
}
size_t dh_key2buf(const DH *dh, unsigned char **pbuf_out)
{
const BIGNUM *pubkey;
unsigned char *pbuf;
const BIGNUM *p;
int p_size;
DH_get0_pqg(dh, &p, NULL, NULL);
DH_get0_key(dh, &pubkey, NULL);
if (p == NULL || pubkey == NULL
|| (p_size = BN_num_bytes(p)) == 0
|| BN_num_bytes(pubkey) == 0) {
DHerr(DH_F_DH_KEY2BUF, DH_R_INVALID_PUBKEY);
return 0;
}
if ((pbuf = OPENSSL_malloc(p_size)) == NULL) {
DHerr(DH_F_DH_KEY2BUF, ERR_R_MALLOC_FAILURE);
return 0;
}
/*
* As per Section 4.2.8.1 of RFC 8446 left pad public
* key with zeros to the size of p
*/
if (BN_bn2binpad(pubkey, pbuf, p_size) < 0) {
OPENSSL_free(pbuf);
DHerr(DH_F_DH_KEY2BUF, DH_R_BN_ERROR);
return 0;
}
*pbuf_out = pbuf;
return p_size;
}
Reference in New Issue View Git Blame Copy Permalink