| /* |
| * Copyright 2019-2020 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 |
| */ |
| |
| #include "internal/ffc.h" |
| |
| /* |
| * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Partial public key validation. |
| * To only be used with ephemeral FFC public keys generated using the approved |
| * safe-prime groups. (Checks that the public key is in the range [2, p - 1] |
| * |
| * ret contains 0 on success, or error flags (see FFC_ERROR_PUBKEY_TOO_SMALL) |
| */ |
| int ossl_ffc_validate_public_key_partial(const FFC_PARAMS *params, |
| const BIGNUM *pub_key, int *ret) |
| { |
| int ok = 0; |
| BIGNUM *tmp = NULL; |
| BN_CTX *ctx = NULL; |
| |
| *ret = 0; |
| ctx = BN_CTX_new_ex(NULL); |
| if (ctx == NULL) |
| goto err; |
| |
| BN_CTX_start(ctx); |
| tmp = BN_CTX_get(ctx); |
| /* Step(1): Verify pub_key >= 2 */ |
| if (tmp == NULL |
| || !BN_set_word(tmp, 1)) |
| goto err; |
| if (BN_cmp(pub_key, tmp) <= 0) { |
| *ret |= FFC_ERROR_PUBKEY_TOO_SMALL; |
| goto err; |
| } |
| /* Step(1): Verify pub_key <= p-2 */ |
| if (BN_copy(tmp, params->p) == NULL |
| || !BN_sub_word(tmp, 1)) |
| goto err; |
| if (BN_cmp(pub_key, tmp) >= 0) { |
| *ret |= FFC_ERROR_PUBKEY_TOO_LARGE; |
| goto err; |
| } |
| ok = 1; |
| err: |
| if (ctx != NULL) { |
| BN_CTX_end(ctx); |
| BN_CTX_free(ctx); |
| } |
| return ok; |
| } |
| |
| /* |
| * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Full public key validation. |
| */ |
| int ossl_ffc_validate_public_key(const FFC_PARAMS *params, |
| const BIGNUM *pub_key, int *ret) |
| { |
| int ok = 0; |
| BIGNUM *tmp = NULL; |
| BN_CTX *ctx = NULL; |
| |
| if (!ossl_ffc_validate_public_key_partial(params, pub_key, ret)) |
| return 0; |
| |
| if (params->q != NULL) { |
| ctx = BN_CTX_new_ex(NULL); |
| if (ctx == NULL) |
| goto err; |
| BN_CTX_start(ctx); |
| tmp = BN_CTX_get(ctx); |
| |
| /* Check pub_key^q == 1 mod p */ |
| if (tmp == NULL |
| || !BN_mod_exp(tmp, pub_key, params->q, params->p, ctx)) |
| goto err; |
| if (!BN_is_one(tmp)) { |
| *ret |= FFC_ERROR_PUBKEY_INVALID; |
| goto err; |
| } |
| } |
| |
| ok = 1; |
| err: |
| if (ctx != NULL) { |
| BN_CTX_end(ctx); |
| BN_CTX_free(ctx); |
| } |
| return ok; |
| } |
| |
| /* |
| * See SP800-56Ar3 Section 5.6.2.1.2: Owner assurance of Private key validity. |
| * Verifies priv_key is in the range [1..upper-1]. The passed in value of upper |
| * is normally params->q but can be 2^N for approved safe prime groups. |
| * Note: This assumes that the domain parameters are valid. |
| */ |
| int ossl_ffc_validate_private_key(const BIGNUM *upper, const BIGNUM *priv, |
| int *ret) |
| { |
| int ok = 0; |
| |
| *ret = 0; |
| |
| if (BN_cmp(priv, BN_value_one()) < 0) { |
| *ret |= FFC_ERROR_PRIVKEY_TOO_SMALL; |
| goto err; |
| } |
| if (BN_cmp(priv, upper) >= 0) { |
| *ret |= FFC_ERROR_PRIVKEY_TOO_LARGE; |
| goto err; |
| } |
| ok = 1; |
| err: |
| return ok; |
| } |