--- /dev/null
+/* ====================================================================
+ * 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/type_check.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, c = 1;
+
+ do {
+ --n;
+ c += counter[n];
+ counter[n] = (uint8_t) c;
+ c >>= 8;
+ } while (n);
+}
+
+OPENSSL_COMPILE_ASSERT((16 % sizeof(size_t)) == 0, bad_size_t_size_ctr);
+
+// 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(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;
+ }
+
+#if STRICT_ALIGNMENT
+ if (((uintptr_t)in | (uintptr_t)out |
+ (uintptr_t)ecount_buf) % 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 = 0; n < 16; n += sizeof(size_t)) {
+ store_word_le(out + n,
+ load_word_le(in + n) ^ load_word_le(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, c = 1;
+
+ do {
+ --n;
+ c += counter[n];
+ counter[n] = (uint8_t) c;
+ c >>= 8;
+ } 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) {
+ OPENSSL_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;
+}
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