diff options
Diffstat (limited to 'crypto/aes/aes_ctr.c')
| -rw-r--r-- | crypto/aes/aes_ctr.c | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/crypto/aes/aes_ctr.c b/crypto/aes/aes_ctr.c new file mode 100644 index 000000000000..f36982be1e26 --- /dev/null +++ b/crypto/aes/aes_ctr.c @@ -0,0 +1,139 @@ +/* crypto/aes/aes_ctr.c -*- mode:C; c-file-style: "eay" -*- */ +/* ==================================================================== + * Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * 3. All advertising materials mentioning features or use of this + * software must display the following acknowledgment: + * "This product includes software developed by the OpenSSL Project + * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" + * + * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to + * endorse or promote products derived from this software without + * prior written permission. For written permission, please contact + * openssl-core@openssl.org. + * + * 5. Products derived from this software may not be called "OpenSSL" + * nor may "OpenSSL" appear in their names without prior written + * permission of the OpenSSL Project. + * + * 6. Redistributions of any form whatsoever must retain the following + * acknowledgment: + * "This product includes software developed by the OpenSSL Project + * for use in the OpenSSL Toolkit (http://www.openssl.org/)" + * + * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY + * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR + * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + * ==================================================================== + * + */ + +#ifndef AES_DEBUG +# ifndef NDEBUG +# define NDEBUG +# endif +#endif +#include <assert.h> + +#include <openssl/aes.h> +#include "aes_locl.h" + +/* NOTE: the IV/counter CTR mode is big-endian. The rest of the AES code + * is endian-neutral. */ + +/* increment counter (128-bit int) by 1 */ +static void AES_ctr128_inc(unsigned char *counter) { + unsigned long c; + + /* Grab bottom dword of counter and increment */ + c = GETU32(counter + 12); + c++; c &= 0xFFFFFFFF; + PUTU32(counter + 12, c); + + /* if no overflow, we're done */ + if (c) + return; + + /* Grab 1st dword of counter and increment */ + c = GETU32(counter + 8); + c++; c &= 0xFFFFFFFF; + PUTU32(counter + 8, c); + + /* if no overflow, we're done */ + if (c) + return; + + /* Grab 2nd dword of counter and increment */ + c = GETU32(counter + 4); + c++; c &= 0xFFFFFFFF; + PUTU32(counter + 4, c); + + /* if no overflow, we're done */ + if (c) + return; + + /* Grab top dword of counter and increment */ + c = GETU32(counter + 0); + c++; c &= 0xFFFFFFFF; + PUTU32(counter + 0, c); +} + +/* The input encrypted as though 128bit counter mode is being + * used. The extra state information to record how much of the + * 128bit block we have used is contained in *num, and the + * encrypted counter is kept in ecount_buf. Both *num and + * ecount_buf must be initialised with zeros before the first + * call to AES_ctr128_encrypt(). + * + * This algorithm assumes that the counter is in the x lower bits + * of the IV (ivec), and that the application has full control over + * overflow and the rest of the IV. This implementation takes NO + * responsability for checking that the counter doesn't overflow + * into the rest of the IV when incremented. + */ +void AES_ctr128_encrypt(const unsigned char *in, unsigned char *out, + const unsigned long length, const AES_KEY *key, + unsigned char ivec[AES_BLOCK_SIZE], + unsigned char ecount_buf[AES_BLOCK_SIZE], + unsigned int *num) { + + unsigned int n; + unsigned long l=length; + + assert(in && out && key && counter && num); + assert(*num < AES_BLOCK_SIZE); + + n = *num; + + while (l--) { + if (n == 0) { + AES_encrypt(ivec, ecount_buf, key); + AES_ctr128_inc(ivec); + } + *(out++) = *(in++) ^ ecount_buf[n]; + n = (n+1) % AES_BLOCK_SIZE; + } + + *num=n; +} |