Add the modes OFB128, CFB128 and CTR128 to AES.

[openssl.git] / crypto / aes / aes_ctr.c

diff --git a/crypto/aes/aes_ctr.c b/crypto/aes/aes_ctr.c
new file mode 100644 (file)
index 0000000..8e80048
--- /dev/null
+++ b/crypto/aes/aes_ctr.c
@@ -0,0 +1,117 @@
+/* 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.
+ * ====================================================================
+ *
+ */
+
+#include <assert.h>
+#include <openssl/aes.h>
+#include "aes_locl.h"
+
+/* NOTE: CTR mode is big-endian.  The rest of the AES code
+ * is endian-neutral. */
+
+/* increment counter (128-bit int) by 2^64 */
+static void AES_ctr128_inc(unsigned char *counter) {
+       unsigned long c;
+
+       /* Grab 3rd dword of counter and increment */
+#ifdef L_ENDIAN
+       c = GETU32(counter + 8);
+       c++;
+       PUTU32(counter + 8, c);
+#else
+       c = GETU32(counter + 4);
+       c++;
+       PUTU32(counter + 4, c);
+#endif
+
+       /* if no overflow, we're done */
+       if (c)
+               return;
+
+       /* Grab top dword of counter and increment */
+#ifdef L_ENDIAN
+       c = GETU32(counter + 12);
+       c++;
+       PUTU32(counter + 12, c);
+#else
+       c = GETU32(counter +  0);
+       c++;
+       PUTU32(counter +  0, c);
+#endif
+
+}
+
+/* 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;
+ */
+void AES_ctr128_encrypt(const unsigned char *in, unsigned char *out,
+       const unsigned long length, const AES_KEY *key,
+       unsigned char *counter, unsigned int *num) {
+
+       unsigned int n;
+       unsigned long l=length;
+       unsigned char tmp[AES_BLOCK_SIZE];
+
+       assert(in && out && key && counter && num);
+
+       n = *num;
+
+       while (l--) {
+               if (n == 0) {
+                       AES_ctr128_inc(counter);
+                       AES_encrypt(counter, tmp, key);
+               }
+               *(out++) = *(in++) ^ tmp[n];
+               n = (n+1) % AES_BLOCK_SIZE;
+       }
+
+       *num=n;
+}