/*
- * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 1995-2023 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
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)
+/*
+ * See SP800-56Ar3 Section 5.7.1.1
+ * Finite Field Cryptography Diffie-Hellman (FFC DH) Primitive
+ */
+int ossl_dh_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
{
BN_CTX *ctx = NULL;
BN_MONT_CTX *mont = NULL;
- BIGNUM *tmp;
+ BIGNUM *z = NULL, *pminus1;
int ret = -1;
-#ifndef FIPS_MODULE
- int check_result;
-#endif
if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS) {
ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
goto err;
}
+ if (dh->params.q != NULL
+ && BN_num_bits(dh->params.q) > OPENSSL_DH_MAX_MODULUS_BITS) {
+ ERR_raise(ERR_LIB_DH, DH_R_Q_TOO_LARGE);
+ goto err;
+ }
+
if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
return 0;
if (ctx == NULL)
goto err;
BN_CTX_start(ctx);
- tmp = BN_CTX_get(ctx);
- if (tmp == NULL)
+ pminus1 = BN_CTX_get(ctx);
+ z = BN_CTX_get(ctx);
+ if (z == NULL)
goto err;
if (dh->priv_key == NULL) {
if (!mont)
goto err;
}
-/* TODO(3.0) : Solve in a PR related to Key validation for DH */
-#ifndef FIPS_MODULE
- if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) {
- ERR_raise(ERR_LIB_DH, DH_R_INVALID_PUBKEY);
- goto err;
- }
-#endif
- if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->params.p, ctx,
+
+ /* (Step 1) Z = pub_key^priv_key mod p */
+ if (!dh->meth->bn_mod_exp(dh, z, pub_key, dh->priv_key, dh->params.p, ctx,
mont)) {
ERR_raise(ERR_LIB_DH, ERR_R_BN_LIB);
goto err;
}
+ /* (Step 2) Error if z <= 1 or z = p - 1 */
+ if (BN_copy(pminus1, dh->params.p) == NULL
+ || !BN_sub_word(pminus1, 1)
+ || BN_cmp(z, BN_value_one()) <= 0
+ || BN_cmp(z, pminus1) == 0) {
+ ERR_raise(ERR_LIB_DH, DH_R_INVALID_SECRET);
+ goto err;
+ }
+
/* return the padded key, i.e. same number of bytes as the modulus */
- ret = BN_bn2binpad(tmp, key, BN_num_bytes(dh->params.p));
+ ret = BN_bn2binpad(z, key, BN_num_bytes(dh->params.p));
err:
+ BN_clear(z); /* (Step 2) destroy intermediate values */
BN_CTX_end(ctx);
BN_CTX_free(ctx);
return ret;
/* compute the key; ret is constant unless compute_key is external */
#ifdef FIPS_MODULE
- ret = compute_key(key, pub_key, dh);
+ ret = ossl_dh_compute_key(key, pub_key, dh);
#else
ret = dh->meth->compute_key(key, pub_key, dh);
#endif
/* rv is constant unless compute_key is external */
#ifdef FIPS_MODULE
- rv = compute_key(key, pub_key, dh);
+ rv = ossl_dh_compute_key(key, pub_key, dh);
#else
rv = dh->meth->compute_key(key, pub_key, dh);
#endif
static DH_METHOD dh_ossl = {
"OpenSSL DH Method",
generate_key,
- compute_key,
+ ossl_dh_compute_key,
dh_bn_mod_exp,
dh_init,
dh_finish,
static int dh_init(DH *dh)
{
dh->flags |= DH_FLAG_CACHE_MONT_P;
- ossl_ffc_params_init(&dh->params);
dh->dirty_cnt++;
return 1;
}
#endif
}
-int dh_generate_public_key(BN_CTX *ctx, const DH *dh, const BIGNUM *priv_key,
- BIGNUM *pub_key)
+int ossl_dh_generate_public_key(BN_CTX *ctx, const DH *dh,
+ const BIGNUM *priv_key, BIGNUM *pub_key)
{
int ret = 0;
BIGNUM *prk = BN_new();
return 0;
}
+ if (dh->params.q != NULL
+ && BN_num_bits(dh->params.q) > OPENSSL_DH_MAX_MODULUS_BITS) {
+ ERR_raise(ERR_LIB_DH, DH_R_Q_TOO_LARGE);
+ return 0;
+ }
+
if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
return 0;
/* Is it an approved safe prime ?*/
if (DH_get_nid(dh) != NID_undef) {
int max_strength =
- ifc_ffc_compute_security_bits(BN_num_bits(dh->params.p));
+ ossl_ifc_ffc_compute_security_bits(BN_num_bits(dh->params.p));
if (dh->params.q == NULL
|| dh->length > BN_num_bits(dh->params.q))
goto err;
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))
+ BN_RAND_BOTTOM_ANY, 0, ctx))
goto err;
/*
* We handle just one known case where g is a quadratic non-residue:
{
/* Do a partial check for invalid p, q, g */
if (!ossl_ffc_params_simple_validate(dh->libctx, &dh->params,
- FFC_PARAM_TYPE_DH))
+ FFC_PARAM_TYPE_DH, NULL))
goto err;
/*
* For FFC FIPS 186-4 keygen
}
}
- if (!dh_generate_public_key(ctx, dh, priv_key, pub_key))
+ if (!ossl_dh_generate_public_key(ctx, dh, priv_key, pub_key))
goto err;
dh->pub_key = pub_key;
return ok;
}
-int dh_buf2key(DH *dh, const unsigned char *buf, size_t len)
+int ossl_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;
+ int ret;
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) {
+ if (p == NULL || 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) {
+ /* Prevent small subgroup attacks per RFC 8446 Section 4.2.8.1 */
+ if (!ossl_dh_check_pub_key_partial(dh, pubkey, &ret)) {
err_reason = DH_R_INVALID_PUBKEY;
goto err;
}
return 0;
}
-size_t dh_key2buf(const DH *dh, unsigned char **pbuf_out, size_t size, int alloc)
+size_t ossl_dh_key2buf(const DH *dh, unsigned char **pbuf_out, size_t size,
+ int alloc)
{
const BIGNUM *pubkey;
unsigned char *pbuf = NULL;
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