/* * 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 * 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 #include "internal/cryptlib.h" #include #include "dh_local.h" #include "crypto/dh.h" /*- * Check that p and g are suitable enough * * p is odd * 1 < g < p - 1 */ int DH_check_params_ex(const DH *dh) { int errflags = 0; if (!DH_check_params(dh, &errflags)) return 0; if ((errflags & DH_CHECK_P_NOT_PRIME) != 0) ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_PRIME); if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0) ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR); if ((errflags & DH_MODULUS_TOO_SMALL) != 0) ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL); if ((errflags & DH_MODULUS_TOO_LARGE) != 0) ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE); return errflags == 0; } #ifdef FIPS_MODULE int DH_check_params(const DH *dh, int *ret) { int nid; *ret = 0; /* * SP800-56A R3 Section 5.5.2 Assurances of Domain Parameter Validity * (1a) The domain parameters correspond to any approved safe prime group. */ nid = DH_get_nid((DH *)dh); if (nid != NID_undef) return 1; /* * OR * (2b) FFC domain params conform to FIPS-186-4 explicit domain param * validity tests. */ return ossl_ffc_params_FIPS186_4_validate(dh->libctx, &dh->params, FFC_PARAM_TYPE_DH, ret, NULL); } #else int DH_check_params(const DH *dh, int *ret) { int ok = 0; BIGNUM *tmp = NULL; BN_CTX *ctx = NULL; *ret = 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 (!BN_is_odd(dh->params.p)) *ret |= DH_CHECK_P_NOT_PRIME; if (BN_is_negative(dh->params.g) || BN_is_zero(dh->params.g) || BN_is_one(dh->params.g)) *ret |= DH_NOT_SUITABLE_GENERATOR; if (BN_copy(tmp, dh->params.p) == NULL || !BN_sub_word(tmp, 1)) goto err; if (BN_cmp(dh->params.g, tmp) >= 0) *ret |= DH_NOT_SUITABLE_GENERATOR; if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) *ret |= DH_MODULUS_TOO_SMALL; if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS) *ret |= DH_MODULUS_TOO_LARGE; ok = 1; err: BN_CTX_end(ctx); BN_CTX_free(ctx); return ok; } #endif /* FIPS_MODULE */ /*- * Check that p is a safe prime and * g is a suitable generator. */ int DH_check_ex(const DH *dh) { int errflags = 0; if (!DH_check(dh, &errflags)) return 0; if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0) ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR); if ((errflags & DH_CHECK_Q_NOT_PRIME) != 0) ERR_raise(ERR_LIB_DH, DH_R_CHECK_Q_NOT_PRIME); if ((errflags & DH_CHECK_INVALID_Q_VALUE) != 0) ERR_raise(ERR_LIB_DH, DH_R_CHECK_INVALID_Q_VALUE); if ((errflags & DH_CHECK_INVALID_J_VALUE) != 0) ERR_raise(ERR_LIB_DH, DH_R_CHECK_INVALID_J_VALUE); if ((errflags & DH_UNABLE_TO_CHECK_GENERATOR) != 0) ERR_raise(ERR_LIB_DH, DH_R_UNABLE_TO_CHECK_GENERATOR); if ((errflags & DH_CHECK_P_NOT_PRIME) != 0) ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_PRIME); if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0) ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_SAFE_PRIME); if ((errflags & DH_MODULUS_TOO_SMALL) != 0) ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL); if ((errflags & DH_MODULUS_TOO_LARGE) != 0) ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE); return errflags == 0; } /* Note: according to documentation - this only checks the params */ int DH_check(const DH *dh, int *ret) { #ifdef FIPS_MODULE return DH_check_params(dh, ret); #else int ok = 0, r, q_good = 0; BN_CTX *ctx = NULL; BIGNUM *t1 = NULL, *t2 = NULL; int nid = DH_get_nid((DH *)dh); *ret = 0; if (nid != NID_undef) return 1; /* Don't do any checks at all with an excessively large modulus */ if (BN_num_bits(dh->params.p) > OPENSSL_DH_CHECK_MAX_MODULUS_BITS) { ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE); *ret = DH_MODULUS_TOO_LARGE | DH_CHECK_P_NOT_PRIME; return 0; } if (!DH_check_params(dh, ret)) return 0; ctx = BN_CTX_new_ex(dh->libctx); if (ctx == NULL) goto err; BN_CTX_start(ctx); t1 = BN_CTX_get(ctx); t2 = BN_CTX_get(ctx); if (t2 == NULL) goto err; if (dh->params.q != NULL) { if (BN_ucmp(dh->params.p, dh->params.q) > 0) q_good = 1; else *ret |= DH_CHECK_INVALID_Q_VALUE; } if (q_good) { if (BN_cmp(dh->params.g, BN_value_one()) <= 0) *ret |= DH_NOT_SUITABLE_GENERATOR; else if (BN_cmp(dh->params.g, dh->params.p) >= 0) *ret |= DH_NOT_SUITABLE_GENERATOR; else { /* Check g^q == 1 mod p */ if (!BN_mod_exp(t1, dh->params.g, dh->params.q, dh->params.p, ctx)) goto err; if (!BN_is_one(t1)) *ret |= DH_NOT_SUITABLE_GENERATOR; } r = BN_check_prime(dh->params.q, ctx, NULL); if (r < 0) goto err; if (!r) *ret |= DH_CHECK_Q_NOT_PRIME; /* Check p == 1 mod q i.e. q divides p - 1 */ if (!BN_div(t1, t2, dh->params.p, dh->params.q, ctx)) goto err; if (!BN_is_one(t2)) *ret |= DH_CHECK_INVALID_Q_VALUE; if (dh->params.j != NULL && BN_cmp(dh->params.j, t1)) *ret |= DH_CHECK_INVALID_J_VALUE; } r = BN_check_prime(dh->params.p, ctx, NULL); if (r < 0) goto err; if (!r) *ret |= DH_CHECK_P_NOT_PRIME; else if (dh->params.q == NULL) { if (!BN_rshift1(t1, dh->params.p)) goto err; r = BN_check_prime(t1, ctx, NULL); if (r < 0) goto err; if (!r) *ret |= DH_CHECK_P_NOT_SAFE_PRIME; } ok = 1; err: BN_CTX_end(ctx); BN_CTX_free(ctx); return ok; #endif /* FIPS_MODULE */ } int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key) { int errflags = 0; if (!DH_check_pub_key(dh, pub_key, &errflags)) return 0; if ((errflags & DH_CHECK_PUBKEY_TOO_SMALL) != 0) ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_TOO_SMALL); if ((errflags & DH_CHECK_PUBKEY_TOO_LARGE) != 0) ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_TOO_LARGE); if ((errflags & DH_CHECK_PUBKEY_INVALID) != 0) ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_INVALID); return errflags == 0; } /* * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Full public key validation. */ int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret) { /* Don't do any checks at all with an excessively large modulus */ if (BN_num_bits(dh->params.p) > OPENSSL_DH_CHECK_MAX_MODULUS_BITS) { ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE); *ret = DH_MODULUS_TOO_LARGE | DH_CHECK_PUBKEY_INVALID; return 0; } if (dh->params.q != NULL && BN_ucmp(dh->params.p, dh->params.q) < 0) { *ret |= DH_CHECK_INVALID_Q_VALUE | DH_CHECK_PUBKEY_INVALID; return 1; } return ossl_ffc_validate_public_key(&dh->params, pub_key, ret); } /* * 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. */ int ossl_dh_check_pub_key_partial(const DH *dh, const BIGNUM *pub_key, int *ret) { return ossl_ffc_validate_public_key_partial(&dh->params, pub_key, ret) && *ret == 0; } int ossl_dh_check_priv_key(const DH *dh, const BIGNUM *priv_key, int *ret) { int ok = 0; BIGNUM *two_powN = NULL, *upper; *ret = 0; two_powN = BN_new(); if (two_powN == NULL) return 0; if (dh->params.q != NULL) { upper = dh->params.q; #ifndef FIPS_MODULE } else if (dh->params.p != NULL) { /* * We do not have q so we just check the key is within some * reasonable range, or the number of bits is equal to dh->length. */ int length = dh->length; if (length == 0) { length = BN_num_bits(dh->params.p) - 1; if (BN_num_bits(priv_key) <= length && BN_num_bits(priv_key) > 1) ok = 1; } else if (BN_num_bits(priv_key) == length) { ok = 1; } goto end; #endif } else { goto end; } /* Is it from an approved Safe prime group ?*/ if (DH_get_nid((DH *)dh) != NID_undef && dh->length != 0) { if (!BN_lshift(two_powN, BN_value_one(), dh->length)) goto end; if (BN_cmp(two_powN, dh->params.q) < 0) upper = two_powN; } if (!ossl_ffc_validate_private_key(upper, priv_key, ret)) goto end; ok = 1; end: BN_free(two_powN); return ok; } /* * FFC pairwise check from SP800-56A R3. * Section 5.6.2.1.4 Owner Assurance of Pair-wise Consistency */ int ossl_dh_check_pairwise(const DH *dh) { int ret = 0; BN_CTX *ctx = NULL; BIGNUM *pub_key = NULL; if (dh->params.p == NULL || dh->params.g == NULL || dh->priv_key == NULL || dh->pub_key == NULL) return 0; ctx = BN_CTX_new_ex(dh->libctx); if (ctx == NULL) goto err; pub_key = BN_new(); if (pub_key == NULL) goto err; /* recalculate the public key = (g ^ priv) mod p */ if (!ossl_dh_generate_public_key(ctx, dh, dh->priv_key, pub_key)) goto err; /* check it matches the existing pubic_key */ ret = BN_cmp(pub_key, dh->pub_key) == 0; err: BN_free(pub_key); BN_CTX_free(ctx); return ret; }