From e23c152aa58f533a224df4bc3d433e2be967f64b Mon Sep 17 00:00:00 2001 From: Arne Schwabe Date: Tue, 19 Oct 2021 20:31:13 +0200 Subject: [PATCH] Remove DES key fixup code This code mainly sets the parity bits in the DES keys. As mbed TLS and OpenSSL already ignore these bits in the DES key and since DES is deprecated, remove this special DES code that is not even needed by the libraries. Signed-off-by: Arne Schwabe Acked-by: Max Fillinger Message-Id: <20211019183127.614175-8-arne@rfc2549.org> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg23014.html Signed-off-by: Gert Doering --- src/openvpn/crypto.c | 46 ------------------------------------ src/openvpn/crypto.h | 2 -- src/openvpn/crypto_backend.h | 9 ------- src/openvpn/crypto_mbedtls.c | 24 ------------------- src/openvpn/crypto_openssl.c | 27 --------------------- src/openvpn/ntlm.c | 1 - src/openvpn/ssl.c | 18 -------------- 7 files changed, 127 deletions(-) diff --git a/src/openvpn/crypto.c b/src/openvpn/crypto.c index 1dfc760f9..ce041153f 100644 --- a/src/openvpn/crypto.c +++ b/src/openvpn/crypto.c @@ -956,45 +956,6 @@ check_key(struct key *key, const struct key_type *kt) return true; } -/* - * Make safe mutations to key to ensure it is valid, - * such as ensuring correct parity on DES keys. - * - * This routine cannot guarantee it will generate a good - * key. You must always call check_key after this routine - * to make sure. - */ -void -fixup_key(struct key *key, const struct key_type *kt) -{ - struct gc_arena gc = gc_new(); - if (kt->cipher) - { -#ifdef ENABLE_DEBUG - const struct key orig = *key; -#endif - const int ndc = key_des_num_cblocks(kt->cipher); - - if (ndc) - { - key_des_fixup(key->cipher, kt->cipher_length, ndc); - } - -#ifdef ENABLE_DEBUG - if (check_debug_level(D_CRYPTO_DEBUG)) - { - if (memcmp(orig.cipher, key->cipher, kt->cipher_length)) - { - dmsg(D_CRYPTO_DEBUG, "CRYPTO INFO: fixup_key: before=%s after=%s", - format_hex(orig.cipher, kt->cipher_length, 0, &gc), - format_hex(key->cipher, kt->cipher_length, 0, &gc)); - } - } -#endif - } - gc_free(&gc); -} - void check_replay_consistency(const struct key_type *kt, bool packet_id) { @@ -1043,10 +1004,6 @@ generate_key_random(struct key *key, const struct key_type *kt) dmsg(D_SHOW_KEY_SOURCE, "Cipher source entropy: %s", format_hex(key->cipher, cipher_len, 0, &gc)); dmsg(D_SHOW_KEY_SOURCE, "HMAC source entropy: %s", format_hex(key->hmac, hmac_len, 0, &gc)); - if (kt) - { - fixup_key(key, kt); - } } while (kt && !check_key(key, kt)); gc_free(&gc); @@ -1589,9 +1546,6 @@ verify_fix_key2(struct key2 *key2, const struct key_type *kt, const char *shared for (i = 0; i < key2->n; ++i) { - /* Fix parity for DES keys and make sure not a weak key */ - fixup_key(&key2->keys[i], kt); - /* This should be a very improbable failure */ if (!check_key(&key2->keys[i], kt)) { diff --git a/src/openvpn/crypto.h b/src/openvpn/crypto.h index 759da4bfb..e9ba21ab2 100644 --- a/src/openvpn/crypto.h +++ b/src/openvpn/crypto.h @@ -288,8 +288,6 @@ void check_replay_consistency(const struct key_type *kt, bool packet_id); bool check_key(struct key *key, const struct key_type *kt); -void fixup_key(struct key *key, const struct key_type *kt); - bool write_key(const struct key *key, const struct key_type *kt, struct buffer *buf); diff --git a/src/openvpn/crypto_backend.h b/src/openvpn/crypto_backend.h index e9447f82f..c201735d9 100644 --- a/src/openvpn/crypto_backend.h +++ b/src/openvpn/crypto_backend.h @@ -170,15 +170,6 @@ int key_des_num_cblocks(const cipher_kt_t *kt); */ bool key_des_check(uint8_t *key, int key_len, int ndc); -/* - * Fix the given DES key, setting its parity to odd. - * - * @param key Key to check - * @param key_len Length of the key, in bytes - * @param ndc Number of DES cblocks that the key is made up of. - */ -void key_des_fixup(uint8_t *key, int key_len, int ndc); - /** * Encrypt the given block, using DES ECB mode * diff --git a/src/openvpn/crypto_mbedtls.c b/src/openvpn/crypto_mbedtls.c index c632849db..ef629136a 100644 --- a/src/openvpn/crypto_mbedtls.c +++ b/src/openvpn/crypto_mbedtls.c @@ -422,11 +422,6 @@ key_des_check(uint8_t *key, int key_len, int ndc) msg(D_CRYPT_ERRORS, "CRYPTO INFO: check_key_DES: weak key detected"); goto err; } - if (0 != mbedtls_des_key_check_key_parity(key)) - { - msg(D_CRYPT_ERRORS, "CRYPTO INFO: check_key_DES: bad parity detected"); - goto err; - } } return true; @@ -434,25 +429,6 @@ err: return false; } -void -key_des_fixup(uint8_t *key, int key_len, int ndc) -{ - int i; - struct buffer b; - - buf_set_read(&b, key, key_len); - for (i = 0; i < ndc; ++i) - { - unsigned char *key = buf_read_alloc(&b, MBEDTLS_DES_KEY_SIZE); - if (!key) - { - msg(D_CRYPT_ERRORS, "CRYPTO INFO: fixup_key_DES: insufficient key material"); - return; - } - mbedtls_des_key_set_parity(key); - } -} - /* * * Generic cipher key type functions diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c index dda46c2f8..c8fe0d0f2 100644 --- a/src/openvpn/crypto_openssl.c +++ b/src/openvpn/crypto_openssl.c @@ -546,12 +546,6 @@ key_des_check(uint8_t *key, int key_len, int ndc) "CRYPTO INFO: check_key_DES: weak key detected"); goto err; } - if (!DES_check_key_parity(dc)) - { - crypto_msg(D_CRYPT_ERRORS, - "CRYPTO INFO: check_key_DES: bad parity detected"); - goto err; - } } return true; @@ -567,27 +561,6 @@ err: #endif } -void -key_des_fixup(uint8_t *key, int key_len, int ndc) -{ - int i; - struct buffer b; - - buf_set_read(&b, key, key_len); - for (i = 0; i < ndc; ++i) - { - DES_cblock *dc = (DES_cblock *) buf_read_alloc(&b, sizeof(DES_cblock)); - if (!dc) - { - msg(D_CRYPT_ERRORS, "CRYPTO INFO: fixup_key_DES: insufficient key material"); - ERR_clear_error(); - return; - } - DES_set_odd_parity(dc); - } -} - - /* * * Generic cipher key type functions diff --git a/src/openvpn/ntlm.c b/src/openvpn/ntlm.c index 3abe3b7e3..28e68ded5 100644 --- a/src/openvpn/ntlm.c +++ b/src/openvpn/ntlm.c @@ -67,7 +67,6 @@ create_des_keys(const unsigned char *hash, unsigned char *key) key[5] = ((hash[4] & 31) << 3) | (hash[5] >> 5); key[6] = ((hash[5] & 63) << 2) | (hash[6] >> 6); key[7] = ((hash[6] & 127) << 1); - key_des_fixup(key, 8, 1); } static void diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c index b2dc48be2..ee416a64c 100644 --- a/src/openvpn/ssl.c +++ b/src/openvpn/ssl.c @@ -1739,24 +1739,6 @@ generate_key_expansion_openvpn_prf(const struct tls_session *session, struct key } secure_memzero(&master, sizeof(master)); - - - /* - * fixup_key only correctly sets DES parity bits if the cipher is a - * DES variant. - * - * The newer OpenSSL and mbed TLS libraries (those that support EKM) - * ignore these bits. - * - * We keep the DES fixup here as compatibility. - * OpenVPN3 never did this fixup anyway. So this code is *probably* not - * required but we keep it for compatibility until we remove DES support - * since it does not hurt either. - */ - for (int i = 0; i < 2; ++i) - { - fixup_key(&key2->keys[i], &session->opt->key_type); - } key2->n = 2; return true; -- 2.47.2