1 /* ====================================================================
2 * Copyright (c) 2008 The OpenSSL Project. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
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18 * "This product includes software developed by the OpenSSL Project
19 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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30 * 6. Redistributions of any form whatsoever must retain the following
32 * "This product includes software developed by the OpenSSL Project
33 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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47 * ==================================================================== */
49 #include <openssl/type_check.h>
57 // NOTE: the IV/counter CTR mode is big-endian. The code itself
60 // increment counter (128-bit int) by 1
61 static void ctr128_inc(uint8_t *counter) {
62 uint32_t n = 16, c = 1;
67 counter[n] = (uint8_t) c;
72 OPENSSL_COMPILE_ASSERT((16 % sizeof(size_t)) == 0, bad_size_t_size_ctr);
74 // The input encrypted as though 128bit counter mode is being used. The extra
75 // state information to record how much of the 128bit block we have used is
76 // contained in *num, and the encrypted counter is kept in ecount_buf. Both
77 // *num and ecount_buf must be initialised with zeros before the first call to
78 // CRYPTO_ctr128_encrypt().
80 // This algorithm assumes that the counter is in the x lower bits of the IV
81 // (ivec), and that the application has full control over overflow and the rest
82 // of the IV. This implementation takes NO responsibility for checking that
83 // the counter doesn't overflow into the rest of the IV when incremented.
84 void CRYPTO_ctr128_encrypt(const uint8_t *in, uint8_t *out, size_t len,
85 const void *key, uint8_t ivec[16],
86 uint8_t ecount_buf[16], unsigned int *num,
90 assert(key && ecount_buf && num);
91 assert(len == 0 || (in && out));
97 *(out++) = *(in++) ^ ecount_buf[n];
103 if (((uintptr_t)in | (uintptr_t)out |
104 (uintptr_t)ecount_buf) % sizeof(size_t) != 0) {
108 (*block)(ivec, ecount_buf, key);
111 out[l] = in[l] ^ ecount_buf[n];
122 (*block)(ivec, ecount_buf, key);
124 for (n = 0; n < 16; n += sizeof(size_t)) {
125 store_word_le(out + n,
126 load_word_le(in + n) ^ load_word_le(ecount_buf + n));
134 (*block)(ivec, ecount_buf, key);
137 out[n] = in[n] ^ ecount_buf[n];
144 // increment upper 96 bits of 128-bit counter by 1
145 static void ctr96_inc(uint8_t *counter) {
146 uint32_t n = 12, c = 1;
151 counter[n] = (uint8_t) c;
156 void CRYPTO_ctr128_encrypt_ctr32(const uint8_t *in, uint8_t *out,
157 size_t len, const void *key,
159 uint8_t ecount_buf[16],
160 unsigned int *num, ctr128_f func) {
161 unsigned int n, ctr32;
163 assert(key && ecount_buf && num);
164 assert(len == 0 || (in && out));
170 *(out++) = *(in++) ^ ecount_buf[n];
175 ctr32 = GETU32(ivec + 12);
177 size_t blocks = len / 16;
178 // 1<<28 is just a not-so-small yet not-so-large number...
179 // Below condition is practically never met, but it has to
180 // be checked for code correctness.
181 if (sizeof(size_t) > sizeof(unsigned int) && blocks > (1U << 28)) {
184 // As (*func) operates on 32-bit counter, caller
185 // has to handle overflow. 'if' below detects the
186 // overflow, which is then handled by limiting the
187 // amount of blocks to the exact overflow point...
188 ctr32 += (uint32_t)blocks;
189 if (ctr32 < blocks) {
193 (*func)(in, out, blocks, key, ivec);
194 // (*func) does not update ivec, caller does:
195 PUTU32(ivec + 12, ctr32);
196 // ... overflow was detected, propogate carry.
206 OPENSSL_memset(ecount_buf, 0, 16);
207 (*func)(ecount_buf, ecount_buf, 1, key, ivec);
209 PUTU32(ivec + 12, ctr32);
214 out[n] = in[n] ^ ecount_buf[n];