73535ab252
This one is a little thorny. All the various block cipher modes functions and callbacks take a void *key. This allows them to be used with multiple kinds of block ciphers. However, the implementations of those callbacks are the normal typed functions, like AES_encrypt. Those take AES_KEY *key. While, at the ABI level, this is perfectly fine, C considers this undefined behavior. If we wish to preserve this genericness, we could either instantiate multiple versions of these mode functions or create wrappers of AES_encrypt, etc., that take void *key. The former means more code and is tedious without C++ templates (maybe someday...). The latter would not be difficult for a compiler to optimize out. C mistakenly allowed comparing function pointers for equality, which means a compiler cannot replace pointers to wrapper functions with the real thing. (That said, the performance-sensitive bits already act in chunks, e.g. ctr128_f, so the function call overhead shouldn't matter.) But our only 128-bit block cipher is AES anyway, so I just switched things to use AES_KEY throughout. AES is doing fine, and hopefully we would have the sense not to pair a hypothetical future block cipher with so many modes! Change-Id: Ied3e843f0e3042a439f09e655b29847ade9d4c7d Reviewed-on: https://boringssl-review.googlesource.com/32107 Reviewed-by: Adam Langley <agl@google.com>
96 lines
3.4 KiB
C
96 lines
3.4 KiB
C
/* ====================================================================
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* Copyright (c) 2008 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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#include <openssl/type_check.h>
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#include <assert.h>
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#include <string.h>
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#include "internal.h"
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OPENSSL_COMPILE_ASSERT((16 % sizeof(size_t)) == 0, bad_size_t_size_ofb);
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void CRYPTO_ofb128_encrypt(const uint8_t *in, uint8_t *out, size_t len,
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const AES_KEY *key, uint8_t ivec[16], unsigned *num,
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block128_f block) {
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assert(in && out && key && ivec && num);
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unsigned n = *num;
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while (n && len) {
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*(out++) = *(in++) ^ ivec[n];
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--len;
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n = (n + 1) % 16;
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}
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while (len >= 16) {
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(*block)(ivec, ivec, key);
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for (; n < 16; n += sizeof(size_t)) {
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size_t a, b;
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OPENSSL_memcpy(&a, in + n, sizeof(size_t));
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OPENSSL_memcpy(&b, ivec + n, sizeof(size_t));
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const size_t c = a ^ b;
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OPENSSL_memcpy(out + n, &c, sizeof(size_t));
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}
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len -= 16;
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out += 16;
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in += 16;
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n = 0;
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}
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if (len) {
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(*block)(ivec, ivec, key);
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while (len--) {
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out[n] = in[n] ^ ivec[n];
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++n;
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}
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}
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*num = n;
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}
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