1 files changed, 219 insertions, 0 deletions
diff --git a/src/crypto/modes/ctr.c b/src/crypto/modes/ctr.c
new file mode 100644
index 0000000..61832ba
--- /dev/null
+++ b/src/crypto/modes/ctr.c
@@ -0,0 +1,219 @@
+/* ====================================================================
+ * 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(in && out && key && ecount_buf && num);
+  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;
+}