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630 lines
23 KiB
C
Executable File
630 lines
23 KiB
C
Executable File
/* $OpenBSD: s3_cbc.c,v 1.22 2020/06/19 21:26:40 tb Exp $ */
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/* ====================================================================
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* Copyright (c) 2012 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* openssl-core@openssl.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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* ====================================================================
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*
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* This product includes cryptographic software written by Eric Young
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* (eay@cryptsoft.com). This product includes software written by Tim
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* Hudson (tjh@cryptsoft.com).
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*
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*/
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#include "ssl_locl.h"
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#include <openssl/md5.h>
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#include <openssl/sha.h>
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/* MAX_HASH_BIT_COUNT_BYTES is the maximum number of bytes in the hash's length
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* field. (SHA-384/512 have 128-bit length.) */
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#define MAX_HASH_BIT_COUNT_BYTES 16
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/* MAX_HASH_BLOCK_SIZE is the maximum hash block size that we'll support.
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* Currently SHA-384/512 has a 128-byte block size and that's the largest
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* supported by TLS.) */
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#define MAX_HASH_BLOCK_SIZE 128
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/* Some utility functions are needed:
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*
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* These macros return the given value with the MSB copied to all the other
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* bits. They use the fact that arithmetic shift shifts-in the sign bit.
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* However, this is not ensured by the C standard so you may need to replace
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* them with something else on odd CPUs. */
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#define DUPLICATE_MSB_TO_ALL(x) ((unsigned int)((int)(x) >> (sizeof(int) * 8 - 1)))
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#define DUPLICATE_MSB_TO_ALL_8(x) ((unsigned char)(DUPLICATE_MSB_TO_ALL(x)))
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/* constant_time_lt returns 0xff if a<b and 0x00 otherwise. */
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static unsigned int
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constant_time_lt(unsigned int a, unsigned int b)
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{
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a -= b;
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return DUPLICATE_MSB_TO_ALL(a);
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}
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/* constant_time_ge returns 0xff if a>=b and 0x00 otherwise. */
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static unsigned int
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constant_time_ge(unsigned int a, unsigned int b)
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{
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a -= b;
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return DUPLICATE_MSB_TO_ALL(~a);
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}
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/* constant_time_eq_8 returns 0xff if a==b and 0x00 otherwise. */
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static unsigned char
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constant_time_eq_8(unsigned int a, unsigned int b)
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{
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unsigned int c = a ^ b;
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c--;
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return DUPLICATE_MSB_TO_ALL_8(c);
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}
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/* tls1_cbc_remove_padding removes the CBC padding from the decrypted, TLS, CBC
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* record in |rec| in constant time and returns 1 if the padding is valid and
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* -1 otherwise. It also removes any explicit IV from the start of the record
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* without leaking any timing about whether there was enough space after the
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* padding was removed.
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*
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* block_size: the block size of the cipher used to encrypt the record.
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* returns:
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* 0: (in non-constant time) if the record is publicly invalid.
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* 1: if the padding was valid
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* -1: otherwise. */
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int
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tls1_cbc_remove_padding(const SSL* s, SSL3_RECORD_INTERNAL *rec,
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unsigned int block_size, unsigned int mac_size)
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{
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unsigned int padding_length, good, to_check, i;
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const unsigned int overhead = 1 /* padding length byte */ + mac_size;
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/* Check if version requires explicit IV */
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if (SSL_USE_EXPLICIT_IV(s)) {
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/* These lengths are all public so we can test them in
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* non-constant time.
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*/
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if (overhead + block_size > rec->length)
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return 0;
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/* We can now safely skip explicit IV */
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rec->data += block_size;
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rec->input += block_size;
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rec->length -= block_size;
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} else if (overhead > rec->length)
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return 0;
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padding_length = rec->data[rec->length - 1];
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good = constant_time_ge(rec->length, overhead + padding_length);
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/* The padding consists of a length byte at the end of the record and
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* then that many bytes of padding, all with the same value as the
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* length byte. Thus, with the length byte included, there are i+1
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* bytes of padding.
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*
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* We can't check just |padding_length+1| bytes because that leaks
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* decrypted information. Therefore we always have to check the maximum
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* amount of padding possible. (Again, the length of the record is
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* public information so we can use it.) */
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to_check = 256; /* maximum amount of padding, inc length byte. */
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if (to_check > rec->length)
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to_check = rec->length;
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for (i = 0; i < to_check; i++) {
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unsigned char mask = constant_time_ge(padding_length, i);
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unsigned char b = rec->data[rec->length - 1 - i];
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/* The final |padding_length+1| bytes should all have the value
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* |padding_length|. Therefore the XOR should be zero. */
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good &= ~(mask&(padding_length ^ b));
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}
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/* If any of the final |padding_length+1| bytes had the wrong value,
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* one or more of the lower eight bits of |good| will be cleared. We
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* AND the bottom 8 bits together and duplicate the result to all the
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* bits. */
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good &= good >> 4;
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good &= good >> 2;
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good &= good >> 1;
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good <<= sizeof(good)*8 - 1;
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good = DUPLICATE_MSB_TO_ALL(good);
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padding_length = good & (padding_length + 1);
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rec->length -= padding_length;
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rec->padding_length = padding_length;
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return (int)((good & 1) | (~good & -1));
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}
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/* ssl3_cbc_copy_mac copies |md_size| bytes from the end of |rec| to |out| in
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* constant time (independent of the concrete value of rec->length, which may
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* vary within a 256-byte window).
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*
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* ssl3_cbc_remove_padding or tls1_cbc_remove_padding must be called prior to
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* this function.
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*
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* On entry:
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* rec->orig_len >= md_size
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* md_size <= EVP_MAX_MD_SIZE
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*
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* If CBC_MAC_ROTATE_IN_PLACE is defined then the rotation is performed with
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* variable accesses in a 64-byte-aligned buffer. Assuming that this fits into
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* a single or pair of cache-lines, then the variable memory accesses don't
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* actually affect the timing. CPUs with smaller cache-lines [if any] are
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* not multi-core and are not considered vulnerable to cache-timing attacks.
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*/
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#define CBC_MAC_ROTATE_IN_PLACE
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void
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ssl3_cbc_copy_mac(unsigned char* out, const SSL3_RECORD_INTERNAL *rec,
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unsigned int md_size, unsigned int orig_len)
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{
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#if defined(CBC_MAC_ROTATE_IN_PLACE)
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unsigned char rotated_mac_buf[64 + EVP_MAX_MD_SIZE];
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unsigned char *rotated_mac;
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#else
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unsigned char rotated_mac[EVP_MAX_MD_SIZE];
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#endif
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/* mac_end is the index of |rec->data| just after the end of the MAC. */
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unsigned int mac_end = rec->length;
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unsigned int mac_start = mac_end - md_size;
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/* scan_start contains the number of bytes that we can ignore because
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* the MAC's position can only vary by 255 bytes. */
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unsigned int scan_start = 0;
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unsigned int i, j;
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unsigned int div_spoiler;
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unsigned int rotate_offset;
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OPENSSL_assert(orig_len >= md_size);
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OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE);
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#if defined(CBC_MAC_ROTATE_IN_PLACE)
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rotated_mac = rotated_mac_buf + ((0 - (size_t)rotated_mac_buf)&63);
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#endif
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/* This information is public so it's safe to branch based on it. */
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if (orig_len > md_size + 255 + 1)
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scan_start = orig_len - (md_size + 255 + 1);
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/* div_spoiler contains a multiple of md_size that is used to cause the
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* modulo operation to be constant time. Without this, the time varies
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* based on the amount of padding when running on Intel chips at least.
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*
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* The aim of right-shifting md_size is so that the compiler doesn't
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* figure out that it can remove div_spoiler as that would require it
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* to prove that md_size is always even, which I hope is beyond it. */
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div_spoiler = md_size >> 1;
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div_spoiler <<= (sizeof(div_spoiler) - 1) * 8;
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rotate_offset = (div_spoiler + mac_start - scan_start) % md_size;
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memset(rotated_mac, 0, md_size);
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for (i = scan_start, j = 0; i < orig_len; i++) {
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unsigned char mac_started = constant_time_ge(i, mac_start);
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unsigned char mac_ended = constant_time_ge(i, mac_end);
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unsigned char b = rec->data[i];
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rotated_mac[j++] |= b & mac_started & ~mac_ended;
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j &= constant_time_lt(j, md_size);
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}
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/* Now rotate the MAC */
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#if defined(CBC_MAC_ROTATE_IN_PLACE)
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j = 0;
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for (i = 0; i < md_size; i++) {
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/* in case cache-line is 32 bytes, touch second line */
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((volatile unsigned char *)rotated_mac)[rotate_offset^32];
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out[j++] = rotated_mac[rotate_offset++];
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rotate_offset &= constant_time_lt(rotate_offset, md_size);
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}
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#else
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memset(out, 0, md_size);
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rotate_offset = md_size - rotate_offset;
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rotate_offset &= constant_time_lt(rotate_offset, md_size);
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for (i = 0; i < md_size; i++) {
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for (j = 0; j < md_size; j++)
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out[j] |= rotated_mac[i] & constant_time_eq_8(j, rotate_offset);
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rotate_offset++;
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rotate_offset &= constant_time_lt(rotate_offset, md_size);
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}
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#endif
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}
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#define l2n(l,c) (*((c)++)=(unsigned char)(((l)>>24)&0xff), \
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*((c)++)=(unsigned char)(((l)>>16)&0xff), \
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*((c)++)=(unsigned char)(((l)>> 8)&0xff), \
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*((c)++)=(unsigned char)(((l) )&0xff))
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#define l2n8(l,c) (*((c)++)=(unsigned char)(((l)>>56)&0xff), \
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*((c)++)=(unsigned char)(((l)>>48)&0xff), \
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*((c)++)=(unsigned char)(((l)>>40)&0xff), \
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*((c)++)=(unsigned char)(((l)>>32)&0xff), \
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*((c)++)=(unsigned char)(((l)>>24)&0xff), \
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*((c)++)=(unsigned char)(((l)>>16)&0xff), \
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*((c)++)=(unsigned char)(((l)>> 8)&0xff), \
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*((c)++)=(unsigned char)(((l) )&0xff))
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/* u32toLE serialises an unsigned, 32-bit number (n) as four bytes at (p) in
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* little-endian order. The value of p is advanced by four. */
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#define u32toLE(n, p) \
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(*((p)++)=(unsigned char)(n), \
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*((p)++)=(unsigned char)(n>>8), \
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*((p)++)=(unsigned char)(n>>16), \
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*((p)++)=(unsigned char)(n>>24))
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/* These functions serialize the state of a hash and thus perform the standard
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* "final" operation without adding the padding and length that such a function
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* typically does. */
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static void
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tls1_md5_final_raw(void* ctx, unsigned char *md_out)
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{
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MD5_CTX *md5 = ctx;
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u32toLE(md5->A, md_out);
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u32toLE(md5->B, md_out);
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u32toLE(md5->C, md_out);
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u32toLE(md5->D, md_out);
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}
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static void
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tls1_sha1_final_raw(void* ctx, unsigned char *md_out)
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{
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SHA_CTX *sha1 = ctx;
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l2n(sha1->h0, md_out);
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l2n(sha1->h1, md_out);
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l2n(sha1->h2, md_out);
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l2n(sha1->h3, md_out);
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l2n(sha1->h4, md_out);
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}
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static void
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tls1_sha256_final_raw(void* ctx, unsigned char *md_out)
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{
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SHA256_CTX *sha256 = ctx;
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unsigned int i;
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for (i = 0; i < 8; i++) {
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l2n(sha256->h[i], md_out);
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}
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}
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static void
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tls1_sha512_final_raw(void* ctx, unsigned char *md_out)
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{
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SHA512_CTX *sha512 = ctx;
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unsigned int i;
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for (i = 0; i < 8; i++) {
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l2n8(sha512->h[i], md_out);
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}
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}
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/* Largest hash context ever used by the functions above. */
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#define LARGEST_DIGEST_CTX SHA512_CTX
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/* Type giving the alignment needed by the above */
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#define LARGEST_DIGEST_CTX_ALIGNMENT SHA_LONG64
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/* ssl3_cbc_record_digest_supported returns 1 iff |ctx| uses a hash function
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* which ssl3_cbc_digest_record supports. */
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char
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ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx)
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{
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switch (EVP_MD_CTX_type(ctx)) {
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case NID_md5:
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case NID_sha1:
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case NID_sha224:
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case NID_sha256:
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case NID_sha384:
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case NID_sha512:
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return 1;
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default:
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return 0;
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}
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}
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/* ssl3_cbc_digest_record computes the MAC of a decrypted, padded TLS
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* record.
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*
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* ctx: the EVP_MD_CTX from which we take the hash function.
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* ssl3_cbc_record_digest_supported must return true for this EVP_MD_CTX.
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* md_out: the digest output. At most EVP_MAX_MD_SIZE bytes will be written.
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* md_out_size: if non-NULL, the number of output bytes is written here.
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* header: the 13-byte, TLS record header.
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* data: the record data itself, less any preceeding explicit IV.
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* data_plus_mac_size: the secret, reported length of the data and MAC
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* once the padding has been removed.
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* data_plus_mac_plus_padding_size: the public length of the whole
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* record, including padding.
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*
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* On entry: by virtue of having been through one of the remove_padding
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* functions, above, we know that data_plus_mac_size is large enough to contain
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* a padding byte and MAC. (If the padding was invalid, it might contain the
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* padding too. )
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*/
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int
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ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, unsigned char* md_out,
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size_t* md_out_size, const unsigned char header[13],
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const unsigned char *data, size_t data_plus_mac_size,
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size_t data_plus_mac_plus_padding_size, const unsigned char *mac_secret,
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unsigned int mac_secret_length)
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{
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union {
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/*
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* Alignment here is to allow this to be cast as SHA512_CTX
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* without losing alignment required by the 64-bit SHA_LONG64
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* integer it contains.
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*/
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LARGEST_DIGEST_CTX_ALIGNMENT align;
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unsigned char c[sizeof(LARGEST_DIGEST_CTX)];
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} md_state;
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void (*md_final_raw)(void *ctx, unsigned char *md_out);
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void (*md_transform)(void *ctx, const unsigned char *block);
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unsigned int md_size, md_block_size = 64;
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unsigned int header_length, variance_blocks,
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len, max_mac_bytes, num_blocks,
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num_starting_blocks, k, mac_end_offset, c, index_a, index_b;
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unsigned int bits; /* at most 18 bits */
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unsigned char length_bytes[MAX_HASH_BIT_COUNT_BYTES];
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/* hmac_pad is the masked HMAC key. */
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unsigned char hmac_pad[MAX_HASH_BLOCK_SIZE];
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unsigned char first_block[MAX_HASH_BLOCK_SIZE];
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unsigned char mac_out[EVP_MAX_MD_SIZE];
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unsigned int i, j, md_out_size_u;
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EVP_MD_CTX md_ctx;
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/* mdLengthSize is the number of bytes in the length field that terminates
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* the hash. */
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unsigned int md_length_size = 8;
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char length_is_big_endian = 1;
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/* This is a, hopefully redundant, check that allows us to forget about
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* many possible overflows later in this function. */
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OPENSSL_assert(data_plus_mac_plus_padding_size < 1024*1024);
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switch (EVP_MD_CTX_type(ctx)) {
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case NID_md5:
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MD5_Init((MD5_CTX*)md_state.c);
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md_final_raw = tls1_md5_final_raw;
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md_transform = (void(*)(void *ctx, const unsigned char *block)) MD5_Transform;
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md_size = 16;
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length_is_big_endian = 0;
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break;
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case NID_sha1:
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SHA1_Init((SHA_CTX*)md_state.c);
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md_final_raw = tls1_sha1_final_raw;
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md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA1_Transform;
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md_size = 20;
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break;
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case NID_sha224:
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SHA224_Init((SHA256_CTX*)md_state.c);
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md_final_raw = tls1_sha256_final_raw;
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md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA256_Transform;
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md_size = 224/8;
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break;
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case NID_sha256:
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SHA256_Init((SHA256_CTX*)md_state.c);
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md_final_raw = tls1_sha256_final_raw;
|
|
md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA256_Transform;
|
|
md_size = 32;
|
|
break;
|
|
case NID_sha384:
|
|
SHA384_Init((SHA512_CTX*)md_state.c);
|
|
md_final_raw = tls1_sha512_final_raw;
|
|
md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA512_Transform;
|
|
md_size = 384/8;
|
|
md_block_size = 128;
|
|
md_length_size = 16;
|
|
break;
|
|
case NID_sha512:
|
|
SHA512_Init((SHA512_CTX*)md_state.c);
|
|
md_final_raw = tls1_sha512_final_raw;
|
|
md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA512_Transform;
|
|
md_size = 64;
|
|
md_block_size = 128;
|
|
md_length_size = 16;
|
|
break;
|
|
default:
|
|
/* ssl3_cbc_record_digest_supported should have been
|
|
* called first to check that the hash function is
|
|
* supported. */
|
|
OPENSSL_assert(0);
|
|
if (md_out_size)
|
|
*md_out_size = 0;
|
|
return 0;
|
|
}
|
|
|
|
OPENSSL_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES);
|
|
OPENSSL_assert(md_block_size <= MAX_HASH_BLOCK_SIZE);
|
|
OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE);
|
|
|
|
header_length = 13;
|
|
|
|
/* variance_blocks is the number of blocks of the hash that we have to
|
|
* calculate in constant time because they could be altered by the
|
|
* padding value.
|
|
*
|
|
* TLSv1 has MACs up to 48 bytes long (SHA-384) and the padding is not
|
|
* required to be minimal. Therefore we say that the final six blocks
|
|
* can vary based on the padding.
|
|
*
|
|
* Later in the function, if the message is short and there obviously
|
|
* cannot be this many blocks then variance_blocks can be reduced. */
|
|
variance_blocks = 6;
|
|
/* From now on we're dealing with the MAC, which conceptually has 13
|
|
* bytes of `header' before the start of the data (TLS) */
|
|
len = data_plus_mac_plus_padding_size + header_length;
|
|
/* max_mac_bytes contains the maximum bytes of bytes in the MAC, including
|
|
* |header|, assuming that there's no padding. */
|
|
max_mac_bytes = len - md_size - 1;
|
|
/* num_blocks is the maximum number of hash blocks. */
|
|
num_blocks = (max_mac_bytes + 1 + md_length_size + md_block_size - 1) / md_block_size;
|
|
/* In order to calculate the MAC in constant time we have to handle
|
|
* the final blocks specially because the padding value could cause the
|
|
* end to appear somewhere in the final |variance_blocks| blocks and we
|
|
* can't leak where. However, |num_starting_blocks| worth of data can
|
|
* be hashed right away because no padding value can affect whether
|
|
* they are plaintext. */
|
|
num_starting_blocks = 0;
|
|
/* k is the starting byte offset into the conceptual header||data where
|
|
* we start processing. */
|
|
k = 0;
|
|
/* mac_end_offset is the index just past the end of the data to be
|
|
* MACed. */
|
|
mac_end_offset = data_plus_mac_size + header_length - md_size;
|
|
/* c is the index of the 0x80 byte in the final hash block that
|
|
* contains application data. */
|
|
c = mac_end_offset % md_block_size;
|
|
/* index_a is the hash block number that contains the 0x80 terminating
|
|
* value. */
|
|
index_a = mac_end_offset / md_block_size;
|
|
/* index_b is the hash block number that contains the 64-bit hash
|
|
* length, in bits. */
|
|
index_b = (mac_end_offset + md_length_size) / md_block_size;
|
|
/* bits is the hash-length in bits. It includes the additional hash
|
|
* block for the masked HMAC key. */
|
|
|
|
if (num_blocks > variance_blocks) {
|
|
num_starting_blocks = num_blocks - variance_blocks;
|
|
k = md_block_size*num_starting_blocks;
|
|
}
|
|
|
|
bits = 8*mac_end_offset;
|
|
/* Compute the initial HMAC block. */
|
|
bits += 8*md_block_size;
|
|
memset(hmac_pad, 0, md_block_size);
|
|
OPENSSL_assert(mac_secret_length <= sizeof(hmac_pad));
|
|
memcpy(hmac_pad, mac_secret, mac_secret_length);
|
|
for (i = 0; i < md_block_size; i++)
|
|
hmac_pad[i] ^= 0x36;
|
|
|
|
md_transform(md_state.c, hmac_pad);
|
|
|
|
if (length_is_big_endian) {
|
|
memset(length_bytes, 0, md_length_size - 4);
|
|
length_bytes[md_length_size - 4] = (unsigned char)(bits >> 24);
|
|
length_bytes[md_length_size - 3] = (unsigned char)(bits >> 16);
|
|
length_bytes[md_length_size - 2] = (unsigned char)(bits >> 8);
|
|
length_bytes[md_length_size - 1] = (unsigned char)bits;
|
|
} else {
|
|
memset(length_bytes, 0, md_length_size);
|
|
length_bytes[md_length_size - 5] = (unsigned char)(bits >> 24);
|
|
length_bytes[md_length_size - 6] = (unsigned char)(bits >> 16);
|
|
length_bytes[md_length_size - 7] = (unsigned char)(bits >> 8);
|
|
length_bytes[md_length_size - 8] = (unsigned char)bits;
|
|
}
|
|
|
|
if (k > 0) {
|
|
/* k is a multiple of md_block_size. */
|
|
memcpy(first_block, header, 13);
|
|
memcpy(first_block + 13, data, md_block_size - 13);
|
|
md_transform(md_state.c, first_block);
|
|
for (i = 1; i < k/md_block_size; i++)
|
|
md_transform(md_state.c, data + md_block_size*i - 13);
|
|
}
|
|
|
|
memset(mac_out, 0, sizeof(mac_out));
|
|
|
|
/* We now process the final hash blocks. For each block, we construct
|
|
* it in constant time. If the |i==index_a| then we'll include the 0x80
|
|
* bytes and zero pad etc. For each block we selectively copy it, in
|
|
* constant time, to |mac_out|. */
|
|
for (i = num_starting_blocks; i <= num_starting_blocks + variance_blocks; i++) {
|
|
unsigned char block[MAX_HASH_BLOCK_SIZE];
|
|
unsigned char is_block_a = constant_time_eq_8(i, index_a);
|
|
unsigned char is_block_b = constant_time_eq_8(i, index_b);
|
|
for (j = 0; j < md_block_size; j++) {
|
|
unsigned char b = 0, is_past_c, is_past_cp1;
|
|
if (k < header_length)
|
|
b = header[k];
|
|
else if (k < data_plus_mac_plus_padding_size + header_length)
|
|
b = data[k - header_length];
|
|
k++;
|
|
|
|
is_past_c = is_block_a & constant_time_ge(j, c);
|
|
is_past_cp1 = is_block_a & constant_time_ge(j, c + 1);
|
|
/* If this is the block containing the end of the
|
|
* application data, and we are at the offset for the
|
|
* 0x80 value, then overwrite b with 0x80. */
|
|
b = (b&~is_past_c) | (0x80&is_past_c);
|
|
/* If this is the block containing the end of the
|
|
* application data and we're past the 0x80 value then
|
|
* just write zero. */
|
|
b = b&~is_past_cp1;
|
|
/* If this is index_b (the final block), but not
|
|
* index_a (the end of the data), then the 64-bit
|
|
* length didn't fit into index_a and we're having to
|
|
* add an extra block of zeros. */
|
|
b &= ~is_block_b | is_block_a;
|
|
|
|
/* The final bytes of one of the blocks contains the
|
|
* length. */
|
|
if (j >= md_block_size - md_length_size) {
|
|
/* If this is index_b, write a length byte. */
|
|
b = (b&~is_block_b) | (is_block_b&length_bytes[j - (md_block_size - md_length_size)]);
|
|
}
|
|
block[j] = b;
|
|
}
|
|
|
|
md_transform(md_state.c, block);
|
|
md_final_raw(md_state.c, block);
|
|
/* If this is index_b, copy the hash value to |mac_out|. */
|
|
for (j = 0; j < md_size; j++)
|
|
mac_out[j] |= block[j]&is_block_b;
|
|
}
|
|
|
|
EVP_MD_CTX_init(&md_ctx);
|
|
if (!EVP_DigestInit_ex(&md_ctx, ctx->digest, NULL /* engine */)) {
|
|
EVP_MD_CTX_cleanup(&md_ctx);
|
|
return 0;
|
|
}
|
|
|
|
/* Complete the HMAC in the standard manner. */
|
|
for (i = 0; i < md_block_size; i++)
|
|
hmac_pad[i] ^= 0x6a;
|
|
|
|
EVP_DigestUpdate(&md_ctx, hmac_pad, md_block_size);
|
|
EVP_DigestUpdate(&md_ctx, mac_out, md_size);
|
|
|
|
EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u);
|
|
if (md_out_size)
|
|
*md_out_size = md_out_size_u;
|
|
EVP_MD_CTX_cleanup(&md_ctx);
|
|
|
|
return 1;
|
|
}
|