/* * Copyright 2019-2023 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 * 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; if (params == NULL || pub_key == NULL || params->p == NULL) { *ret = FFC_ERROR_PASSED_NULL_PARAM; return 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 (priv == NULL || upper == NULL) { *ret = FFC_ERROR_PASSED_NULL_PARAM; goto err; } 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; }