Following the license change, modify the boilerplates in crypto/aes/
[openssl.git] / crypto / aes / aes_ige.c
index 2082d06..e19922a 100644 (file)
-/* crypto/aes/aes_ige.c -*- mode:C; c-file-style: "eay" -*- */
-/* ====================================================================
- * Copyright (c) 2006 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.
- * ====================================================================
+/*
+ * Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
  *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
  */
 
-#include "cryptlib.h"
+#include "internal/cryptlib.h"
 
 #include <openssl/aes.h>
 #include "aes_locl.h"
 
-/*
-static void hexdump(FILE *f,const char *title,const unsigned char *s,int l)
-    {
-    int n=0;
+#define N_WORDS (AES_BLOCK_SIZE / sizeof(unsigned long))
+typedef struct {
+    unsigned long data[N_WORDS];
+} aes_block_t;
 
-    fprintf(f,"%s",title);
-    for( ; n < l ; ++n)
-               {
-               if((n%16) == 0)
-                       fprintf(f,"\n%04x",n);
-               fprintf(f," %02x",s[n]);
-               }
-    fprintf(f,"\n");
-    }
-*/
+/* XXX: probably some better way to do this */
+#if defined(__i386__) || defined(__x86_64__)
+# define UNALIGNED_MEMOPS_ARE_FAST 1
+#else
+# define UNALIGNED_MEMOPS_ARE_FAST 0
+#endif
+
+#if UNALIGNED_MEMOPS_ARE_FAST
+# define load_block(d, s)        (d) = *(const aes_block_t *)(s)
+# define store_block(d, s)       *(aes_block_t *)(d) = (s)
+#else
+# define load_block(d, s)        memcpy((d).data, (s), AES_BLOCK_SIZE)
+# define store_block(d, s)       memcpy((d), (s).data, AES_BLOCK_SIZE)
+#endif
 
 /* N.B. The IV for this mode is _twice_ the block size */
 
 void AES_ige_encrypt(const unsigned char *in, unsigned char *out,
-                                        const unsigned long length, const AES_KEY *key,
-                                        unsigned char *ivec, const int enc)
-       {
-       unsigned long n;
-       unsigned long len = length;
-       unsigned char tmp[AES_BLOCK_SIZE];
-       unsigned char tmp2[AES_BLOCK_SIZE];
-       unsigned char prev[AES_BLOCK_SIZE];
-       const unsigned char *iv = ivec;
-       const unsigned char *iv2 = ivec + AES_BLOCK_SIZE;
+                     size_t length, const AES_KEY *key,
+                     unsigned char *ivec, const int enc)
+{
+    size_t n;
+    size_t len = length;
+
+    if (length == 0)
+        return;
 
-       OPENSSL_assert(in && out && key && ivec);
-       OPENSSL_assert((AES_ENCRYPT == enc)||(AES_DECRYPT == enc));
-       OPENSSL_assert((length%AES_BLOCK_SIZE) == 0);
+    OPENSSL_assert(in && out && key && ivec);
+    OPENSSL_assert((AES_ENCRYPT == enc) || (AES_DECRYPT == enc));
+    OPENSSL_assert((length % AES_BLOCK_SIZE) == 0);
 
-       if (AES_ENCRYPT == enc)
-               {
-               /* XXX: Do a separate case for when in != out (strictly should
-                  check for overlap, too) */
-               while (len >= AES_BLOCK_SIZE)
-                       {
-                       /*                      hexdump(stdout, "in", in, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout, "iv", iv, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               out[n] = in[n] ^ iv[n];
-                       /*                      hexdump(stdout, "in ^ iv", out, AES_BLOCK_SIZE); */
-                       AES_encrypt(out, out, key);
-                       /*                      hexdump(stdout,"enc", out, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout,"iv2", iv2, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               out[n] ^= iv2[n];
-                       /*                      hexdump(stdout,"out", out, AES_BLOCK_SIZE); */
-                       iv = out;
-                       memcpy(prev, in, AES_BLOCK_SIZE);
-                       iv2 = prev;
-                       len -= AES_BLOCK_SIZE;
-                       in += AES_BLOCK_SIZE;
-                       out += AES_BLOCK_SIZE;
-                       }
-               memcpy(ivec, iv, AES_BLOCK_SIZE);
-               memcpy(ivec + AES_BLOCK_SIZE, iv2, AES_BLOCK_SIZE);
-               }
-       else
-               {
-               while (len >= AES_BLOCK_SIZE)
-                       {
-                       memcpy(tmp, in, AES_BLOCK_SIZE);
-                       memcpy(tmp2, in, AES_BLOCK_SIZE);
-                       /*                      hexdump(stdout, "in", in, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout, "iv2", iv2, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               tmp[n] ^= iv2[n];
-                       /*                      hexdump(stdout, "in ^ iv2", tmp, AES_BLOCK_SIZE); */
-                       AES_decrypt(tmp, out, key);
-                       /*                      hexdump(stdout, "dec", out, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout, "iv", ivec, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               out[n] ^= ivec[n];
-                       /*                      hexdump(stdout, "out", out, AES_BLOCK_SIZE); */
-                       memcpy(ivec, tmp2, AES_BLOCK_SIZE);
-                       iv2 = out;
-                       len -= AES_BLOCK_SIZE;
-                       in += AES_BLOCK_SIZE;
-                       out += AES_BLOCK_SIZE;
-                       }
-               memcpy(ivec + AES_BLOCK_SIZE, iv2, AES_BLOCK_SIZE);
-               }
-       }
+    len = length / AES_BLOCK_SIZE;
+
+    if (AES_ENCRYPT == enc) {
+        if (in != out &&
+            (UNALIGNED_MEMOPS_ARE_FAST
+             || ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(long) ==
+             0)) {
+            aes_block_t *ivp = (aes_block_t *) ivec;
+            aes_block_t *iv2p = (aes_block_t *) (ivec + AES_BLOCK_SIZE);
+
+            while (len) {
+                aes_block_t *inp = (aes_block_t *) in;
+                aes_block_t *outp = (aes_block_t *) out;
+
+                for (n = 0; n < N_WORDS; ++n)
+                    outp->data[n] = inp->data[n] ^ ivp->data[n];
+                AES_encrypt((unsigned char *)outp->data,
+                            (unsigned char *)outp->data, key);
+                for (n = 0; n < N_WORDS; ++n)
+                    outp->data[n] ^= iv2p->data[n];
+                ivp = outp;
+                iv2p = inp;
+                --len;
+                in += AES_BLOCK_SIZE;
+                out += AES_BLOCK_SIZE;
+            }
+            memcpy(ivec, ivp->data, AES_BLOCK_SIZE);
+            memcpy(ivec + AES_BLOCK_SIZE, iv2p->data, AES_BLOCK_SIZE);
+        } else {
+            aes_block_t tmp, tmp2;
+            aes_block_t iv;
+            aes_block_t iv2;
+
+            load_block(iv, ivec);
+            load_block(iv2, ivec + AES_BLOCK_SIZE);
+
+            while (len) {
+                load_block(tmp, in);
+                for (n = 0; n < N_WORDS; ++n)
+                    tmp2.data[n] = tmp.data[n] ^ iv.data[n];
+                AES_encrypt((unsigned char *)tmp2.data,
+                            (unsigned char *)tmp2.data, key);
+                for (n = 0; n < N_WORDS; ++n)
+                    tmp2.data[n] ^= iv2.data[n];
+                store_block(out, tmp2);
+                iv = tmp2;
+                iv2 = tmp;
+                --len;
+                in += AES_BLOCK_SIZE;
+                out += AES_BLOCK_SIZE;
+            }
+            memcpy(ivec, iv.data, AES_BLOCK_SIZE);
+            memcpy(ivec + AES_BLOCK_SIZE, iv2.data, AES_BLOCK_SIZE);
+        }
+    } else {
+        if (in != out &&
+            (UNALIGNED_MEMOPS_ARE_FAST
+             || ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(long) ==
+             0)) {
+            aes_block_t *ivp = (aes_block_t *) ivec;
+            aes_block_t *iv2p = (aes_block_t *) (ivec + AES_BLOCK_SIZE);
+
+            while (len) {
+                aes_block_t tmp;
+                aes_block_t *inp = (aes_block_t *) in;
+                aes_block_t *outp = (aes_block_t *) out;
+
+                for (n = 0; n < N_WORDS; ++n)
+                    tmp.data[n] = inp->data[n] ^ iv2p->data[n];
+                AES_decrypt((unsigned char *)tmp.data,
+                            (unsigned char *)outp->data, key);
+                for (n = 0; n < N_WORDS; ++n)
+                    outp->data[n] ^= ivp->data[n];
+                ivp = inp;
+                iv2p = outp;
+                --len;
+                in += AES_BLOCK_SIZE;
+                out += AES_BLOCK_SIZE;
+            }
+            memcpy(ivec, ivp->data, AES_BLOCK_SIZE);
+            memcpy(ivec + AES_BLOCK_SIZE, iv2p->data, AES_BLOCK_SIZE);
+        } else {
+            aes_block_t tmp, tmp2;
+            aes_block_t iv;
+            aes_block_t iv2;
+
+            load_block(iv, ivec);
+            load_block(iv2, ivec + AES_BLOCK_SIZE);
+
+            while (len) {
+                load_block(tmp, in);
+                tmp2 = tmp;
+                for (n = 0; n < N_WORDS; ++n)
+                    tmp.data[n] ^= iv2.data[n];
+                AES_decrypt((unsigned char *)tmp.data,
+                            (unsigned char *)tmp.data, key);
+                for (n = 0; n < N_WORDS; ++n)
+                    tmp.data[n] ^= iv.data[n];
+                store_block(out, tmp);
+                iv = tmp2;
+                iv2 = tmp;
+                --len;
+                in += AES_BLOCK_SIZE;
+                out += AES_BLOCK_SIZE;
+            }
+            memcpy(ivec, iv.data, AES_BLOCK_SIZE);
+            memcpy(ivec + AES_BLOCK_SIZE, iv2.data, AES_BLOCK_SIZE);
+        }
+    }
+}
 
 /*
  * Note that its effectively impossible to do biIGE in anything other
@@ -150,134 +167,118 @@ void AES_ige_encrypt(const unsigned char *in, unsigned char *out,
 /* N.B. The IV for this mode is _four times_ the block size */
 
 void AES_bi_ige_encrypt(const unsigned char *in, unsigned char *out,
-                                               const unsigned long length, const AES_KEY *key,
-                                               const AES_KEY *key2, const unsigned char *ivec,
-                                               const int enc)
-       {
-       unsigned long n;
-       unsigned long len = length;
-       unsigned char tmp[AES_BLOCK_SIZE];
-       unsigned char tmp2[AES_BLOCK_SIZE];
-       unsigned char tmp3[AES_BLOCK_SIZE];
-       unsigned char prev[AES_BLOCK_SIZE];
-       const unsigned char *iv;
-       const unsigned char *iv2;
-
-       OPENSSL_assert(in && out && key && ivec);
-       OPENSSL_assert((AES_ENCRYPT == enc)||(AES_DECRYPT == enc));
-       OPENSSL_assert((length%AES_BLOCK_SIZE) == 0);
+                        size_t length, const AES_KEY *key,
+                        const AES_KEY *key2, const unsigned char *ivec,
+                        const int enc)
+{
+    size_t n;
+    size_t len = length;
+    unsigned char tmp[AES_BLOCK_SIZE];
+    unsigned char tmp2[AES_BLOCK_SIZE];
+    unsigned char tmp3[AES_BLOCK_SIZE];
+    unsigned char prev[AES_BLOCK_SIZE];
+    const unsigned char *iv;
+    const unsigned char *iv2;
 
-       if (AES_ENCRYPT == enc)
-               {
-               /* XXX: Do a separate case for when in != out (strictly should
-                  check for overlap, too) */
+    OPENSSL_assert(in && out && key && ivec);
+    OPENSSL_assert((AES_ENCRYPT == enc) || (AES_DECRYPT == enc));
+    OPENSSL_assert((length % AES_BLOCK_SIZE) == 0);
 
-               /* First the forward pass */ 
-               iv = ivec;
-               iv2 = ivec + AES_BLOCK_SIZE;
-               while (len >= AES_BLOCK_SIZE)
-                       {
-                       /*                      hexdump(stdout, "in", in, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout, "iv", iv, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               out[n] = in[n] ^ iv[n];
-                       /*                      hexdump(stdout, "in ^ iv", out, AES_BLOCK_SIZE); */
-                       AES_encrypt(out, out, key);
-                       /*                      hexdump(stdout,"enc", out, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout,"iv2", iv2, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               out[n] ^= iv2[n];
-                       /*                      hexdump(stdout,"out", out, AES_BLOCK_SIZE); */
-                       iv = out;
-                       memcpy(prev, in, AES_BLOCK_SIZE);
-                       iv2 = prev;
-                       len -= AES_BLOCK_SIZE;
-                       in += AES_BLOCK_SIZE;
-                       out += AES_BLOCK_SIZE;
-                       }
+    if (AES_ENCRYPT == enc) {
+        /*
+         * XXX: Do a separate case for when in != out (strictly should check
+         * for overlap, too)
+         */
 
-               /* And now backwards */
-               iv = ivec + AES_BLOCK_SIZE*2;
-               iv2 = ivec + AES_BLOCK_SIZE*3;
-               len = length;
-               while(len >= AES_BLOCK_SIZE)
-                       {
-                       out -= AES_BLOCK_SIZE;
-                       /*                      hexdump(stdout, "intermediate", out, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout, "iv", iv, AES_BLOCK_SIZE); */
-                       /* XXX: reduce copies by alternating between buffers */
-                       memcpy(tmp, out, AES_BLOCK_SIZE);
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               out[n] ^= iv[n];
-                       /*                      hexdump(stdout, "out ^ iv", out, AES_BLOCK_SIZE); */
-                       AES_encrypt(out, out, key);
-                       /*                      hexdump(stdout,"enc", out, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout,"iv2", iv2, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               out[n] ^= iv2[n];
-                       /*                      hexdump(stdout,"out", out, AES_BLOCK_SIZE); */
-                       iv = out;
-                       memcpy(prev, tmp, AES_BLOCK_SIZE);
-                       iv2 = prev;
-                       len -= AES_BLOCK_SIZE;
-                       }
-               }
-       else
-               {
-               /* First backwards */
-               iv = ivec + AES_BLOCK_SIZE*2;
-               iv2 = ivec + AES_BLOCK_SIZE*3;
-               in += length;
-               out += length;
-               while (len >= AES_BLOCK_SIZE)
-                       {
-                       in -= AES_BLOCK_SIZE;
-                       out -= AES_BLOCK_SIZE;
-                       memcpy(tmp, in, AES_BLOCK_SIZE);
-                       memcpy(tmp2, in, AES_BLOCK_SIZE);
-                       /*                      hexdump(stdout, "in", in, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout, "iv2", iv2, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               tmp[n] ^= iv2[n];
-                       /*                      hexdump(stdout, "in ^ iv2", tmp, AES_BLOCK_SIZE); */
-                       AES_decrypt(tmp, out, key);
-                       /*                      hexdump(stdout, "dec", out, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout, "iv", iv, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               out[n] ^= iv[n];
-                       /*                      hexdump(stdout, "out", out, AES_BLOCK_SIZE); */
-                       memcpy(tmp3, tmp2, AES_BLOCK_SIZE);
-                       iv = tmp3;
-                       iv2 = out;
-                       len -= AES_BLOCK_SIZE;
-                       }
+        /* First the forward pass */
+        iv = ivec;
+        iv2 = ivec + AES_BLOCK_SIZE;
+        while (len >= AES_BLOCK_SIZE) {
+            for (n = 0; n < AES_BLOCK_SIZE; ++n)
+                out[n] = in[n] ^ iv[n];
+            AES_encrypt(out, out, key);
+            for (n = 0; n < AES_BLOCK_SIZE; ++n)
+                out[n] ^= iv2[n];
+            iv = out;
+            memcpy(prev, in, AES_BLOCK_SIZE);
+            iv2 = prev;
+            len -= AES_BLOCK_SIZE;
+            in += AES_BLOCK_SIZE;
+            out += AES_BLOCK_SIZE;
+        }
 
-               /* And now forwards */
-               iv = ivec;
-               iv2 = ivec + AES_BLOCK_SIZE;
-               len = length;
-               while (len >= AES_BLOCK_SIZE)
-                       {
-                       memcpy(tmp, out, AES_BLOCK_SIZE);
-                       memcpy(tmp2, out, AES_BLOCK_SIZE);
-                       /*                      hexdump(stdout, "intermediate", out, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout, "iv2", iv2, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               tmp[n] ^= iv2[n];
-                       /*                      hexdump(stdout, "out ^ iv2", tmp, AES_BLOCK_SIZE); */
-                       AES_decrypt(tmp, out, key);
-                       /*                      hexdump(stdout, "dec", out, AES_BLOCK_SIZE); */
-                       /*                      hexdump(stdout, "iv", ivec, AES_BLOCK_SIZE); */
-                       for(n=0 ; n < AES_BLOCK_SIZE ; ++n)
-                               out[n] ^= iv[n];
-                       /*                      hexdump(stdout, "out", out, AES_BLOCK_SIZE); */
-                       memcpy(tmp3, tmp2, AES_BLOCK_SIZE);
-                       iv = tmp3;
-                       iv2 = out;
-                       len -= AES_BLOCK_SIZE;
-                       in += AES_BLOCK_SIZE;
-                       out += AES_BLOCK_SIZE;
-                       }
+        /* And now backwards */
+        iv = ivec + AES_BLOCK_SIZE * 2;
+        iv2 = ivec + AES_BLOCK_SIZE * 3;
+        len = length;
+        while (len >= AES_BLOCK_SIZE) {
+            out -= AES_BLOCK_SIZE;
+            /*
+             * XXX: reduce copies by alternating between buffers
+             */
+            memcpy(tmp, out, AES_BLOCK_SIZE);
+            for (n = 0; n < AES_BLOCK_SIZE; ++n)
+                out[n] ^= iv[n];
+            /*
+             * hexdump(stdout, "out ^ iv", out, AES_BLOCK_SIZE);
+             */
+            AES_encrypt(out, out, key);
+            /*
+             * hexdump(stdout,"enc", out, AES_BLOCK_SIZE);
+             */
+            /*
+             * hexdump(stdout,"iv2", iv2, AES_BLOCK_SIZE);
+             */
+            for (n = 0; n < AES_BLOCK_SIZE; ++n)
+                out[n] ^= iv2[n];
+            /*
+             * hexdump(stdout,"out", out, AES_BLOCK_SIZE);
+             */
+            iv = out;
+            memcpy(prev, tmp, AES_BLOCK_SIZE);
+            iv2 = prev;
+            len -= AES_BLOCK_SIZE;
+        }
+    } else {
+        /* First backwards */
+        iv = ivec + AES_BLOCK_SIZE * 2;
+        iv2 = ivec + AES_BLOCK_SIZE * 3;
+        in += length;
+        out += length;
+        while (len >= AES_BLOCK_SIZE) {
+            in -= AES_BLOCK_SIZE;
+            out -= AES_BLOCK_SIZE;
+            memcpy(tmp, in, AES_BLOCK_SIZE);
+            memcpy(tmp2, in, AES_BLOCK_SIZE);
+            for (n = 0; n < AES_BLOCK_SIZE; ++n)
+                tmp[n] ^= iv2[n];
+            AES_decrypt(tmp, out, key);
+            for (n = 0; n < AES_BLOCK_SIZE; ++n)
+                out[n] ^= iv[n];
+            memcpy(tmp3, tmp2, AES_BLOCK_SIZE);
+            iv = tmp3;
+            iv2 = out;
+            len -= AES_BLOCK_SIZE;
+        }
 
-               }
-       }
+        /* And now forwards */
+        iv = ivec;
+        iv2 = ivec + AES_BLOCK_SIZE;
+        len = length;
+        while (len >= AES_BLOCK_SIZE) {
+            memcpy(tmp, out, AES_BLOCK_SIZE);
+            memcpy(tmp2, out, AES_BLOCK_SIZE);
+            for (n = 0; n < AES_BLOCK_SIZE; ++n)
+                tmp[n] ^= iv2[n];
+            AES_decrypt(tmp, out, key);
+            for (n = 0; n < AES_BLOCK_SIZE; ++n)
+                out[n] ^= iv[n];
+            memcpy(tmp3, tmp2, AES_BLOCK_SIZE);
+            iv = tmp3;
+            iv2 = out;
+            len -= AES_BLOCK_SIZE;
+            in += AES_BLOCK_SIZE;
+            out += AES_BLOCK_SIZE;
+        }
+    }
+}