| /* ==================================================================== |
| * Copyright (c) 2008 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. |
| * ==================================================================== */ |
| #include <openssl/modes.h> |
| |
| #include <assert.h> |
| #include <string.h> |
| |
| #include "internal.h" |
| |
| |
| /* NOTE: the IV/counter CTR mode is big-endian. The code itself |
| * is endian-neutral. */ |
| |
| /* increment counter (128-bit int) by 1 */ |
| static void ctr128_inc(uint8_t *counter) { |
| uint32_t n = 16; |
| uint8_t c; |
| |
| do { |
| --n; |
| c = counter[n]; |
| ++c; |
| counter[n] = c; |
| if (c) { |
| return; |
| } |
| } while (n); |
| } |
| |
| /* 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 |
| * CRYPTO_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 responsibility for checking that |
| * the counter doesn't overflow into the rest of the IV when incremented. */ |
| void CRYPTO_ctr128_encrypt(const uint8_t *in, uint8_t *out, size_t len, |
| const void *key, uint8_t ivec[16], |
| uint8_t ecount_buf[16], unsigned int *num, |
| block128_f block) { |
| unsigned int n; |
| |
| assert(in && out && key && ecount_buf && num); |
| assert(*num < 16); |
| assert((16 % sizeof(size_t)) == 0); |
| |
| n = *num; |
| |
| while (n && len) { |
| *(out++) = *(in++) ^ ecount_buf[n]; |
| --len; |
| n = (n + 1) % 16; |
| } |
| |
| #if STRICT_ALIGNMENT |
| if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) { |
| size_t l = 0; |
| while (l < len) { |
| if (n == 0) { |
| (*block)(ivec, ecount_buf, key); |
| ctr128_inc(ivec); |
| } |
| out[l] = in[l] ^ ecount_buf[n]; |
| ++l; |
| n = (n + 1) % 16; |
| } |
| |
| *num = n; |
| return; |
| } |
| #endif |
| |
| while (len >= 16) { |
| (*block)(ivec, ecount_buf, key); |
| ctr128_inc(ivec); |
| for (; n < 16; n += sizeof(size_t)) { |
| *(size_t *)(out + n) = *(size_t *)(in + n) ^ *(size_t *)(ecount_buf + n); |
| } |
| len -= 16; |
| out += 16; |
| in += 16; |
| n = 0; |
| } |
| if (len) { |
| (*block)(ivec, ecount_buf, key); |
| ctr128_inc(ivec); |
| while (len--) { |
| out[n] = in[n] ^ ecount_buf[n]; |
| ++n; |
| } |
| } |
| *num = n; |
| } |
| |
| /* increment upper 96 bits of 128-bit counter by 1 */ |
| static void ctr96_inc(uint8_t *counter) { |
| uint32_t n = 12; |
| uint8_t c; |
| |
| do { |
| --n; |
| c = counter[n]; |
| ++c; |
| counter[n] = c; |
| if (c) { |
| return; |
| } |
| } while (n); |
| } |
| |
| void CRYPTO_ctr128_encrypt_ctr32(const uint8_t *in, uint8_t *out, |
| size_t len, const void *key, |
| uint8_t ivec[16], |
| uint8_t ecount_buf[16], |
| unsigned int *num, ctr128_f func) { |
| unsigned int n, ctr32; |
| |
| assert(key && ecount_buf && num); |
| assert(len == 0 || (in && out)); |
| assert(*num < 16); |
| |
| n = *num; |
| |
| while (n && len) { |
| *(out++) = *(in++) ^ ecount_buf[n]; |
| --len; |
| n = (n + 1) % 16; |
| } |
| |
| ctr32 = GETU32(ivec + 12); |
| while (len >= 16) { |
| size_t blocks = len / 16; |
| /* 1<<28 is just a not-so-small yet not-so-large number... |
| * Below condition is practically never met, but it has to |
| * be checked for code correctness. */ |
| if (sizeof(size_t) > sizeof(unsigned int) && blocks > (1U << 28)) { |
| blocks = (1U << 28); |
| } |
| /* As (*func) operates on 32-bit counter, caller |
| * has to handle overflow. 'if' below detects the |
| * overflow, which is then handled by limiting the |
| * amount of blocks to the exact overflow point... */ |
| ctr32 += (uint32_t)blocks; |
| if (ctr32 < blocks) { |
| blocks -= ctr32; |
| ctr32 = 0; |
| } |
| (*func)(in, out, blocks, key, ivec); |
| /* (*func) does not update ivec, caller does: */ |
| PUTU32(ivec + 12, ctr32); |
| /* ... overflow was detected, propogate carry. */ |
| if (ctr32 == 0) { |
| ctr96_inc(ivec); |
| } |
| blocks *= 16; |
| len -= blocks; |
| out += blocks; |
| in += blocks; |
| } |
| if (len) { |
| memset(ecount_buf, 0, 16); |
| (*func)(ecount_buf, ecount_buf, 1, key, ivec); |
| ++ctr32; |
| PUTU32(ivec + 12, ctr32); |
| if (ctr32 == 0) { |
| ctr96_inc(ivec); |
| } |
| while (len--) { |
| out[n] = in[n] ^ ecount_buf[n]; |
| ++n; |
| } |
| } |
| |
| *num = n; |
| } |