From 5c3f177b3467ab7ec30f34c11238eb62d3d56b6a Mon Sep 17 00:00:00 2001
From: Jerome Forissier <jerome.forissier@linaro.org>
Date: Tue, 7 Jul 2015 16:47:55 +0200
Subject: [PATCH] Add function pointers for accelerated XTS to
 ltc_cipher_descriptor

Similar to what already exists for other modes.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
---
 src/ciphers/aes/aes.c                    |  8 ++---
 src/ciphers/anubis.c                     |  2 +-
 src/ciphers/blowfish.c                   |  2 +-
 src/ciphers/camellia.c                   |  2 +-
 src/ciphers/cast5.c                      |  2 +-
 src/ciphers/des.c                        |  4 +--
 src/ciphers/kasumi.c                     |  2 +-
 src/ciphers/khazad.c                     |  2 +-
 src/ciphers/kseed.c                      |  2 +-
 src/ciphers/multi2.c                     |  2 +-
 src/ciphers/noekeon.c                    |  2 +-
 src/ciphers/rc2.c                        |  2 +-
 src/ciphers/rc5.c                        |  2 +-
 src/ciphers/rc6.c                        |  2 +-
 src/ciphers/safer/safer.c                |  8 ++---
 src/ciphers/safer/saferp.c               |  2 +-
 src/ciphers/skipjack.c                   |  2 +-
 src/ciphers/twofish/twofish.c            |  2 +-
 src/ciphers/xtea.c                       |  2 +-
 src/headers/tomcrypt_cipher.h            | 30 ++++++++++++++++++
 src/misc/crypt/crypt_cipher_descriptor.c |  2 +-
 src/modes/xts/xts_decrypt.c              | 37 +++++++++++++++-------
 src/modes/xts/xts_encrypt.c              | 40 +++++++++++++++++-------
 23 files changed, 111 insertions(+), 50 deletions(-)

diff --git a/src/ciphers/aes/aes.c b/src/ciphers/aes/aes.c
index aea8e19..cc9d99f 100644
--- a/src/ciphers/aes/aes.c
+++ b/src/ciphers/aes/aes.c
@@ -49,7 +49,7 @@ const struct ltc_cipher_descriptor rijndael_desc =
     6,
     16, 32, 16, 10,
     SETUP, ECB_ENC, ECB_DEC, ECB_TEST, ECB_DONE, ECB_KS,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 const struct ltc_cipher_descriptor aes_desc =
@@ -58,7 +58,7 @@ const struct ltc_cipher_descriptor aes_desc =
     6,
     16, 32, 16, 10,
     SETUP, ECB_ENC, ECB_DEC, ECB_TEST, ECB_DONE, ECB_KS,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 #else
@@ -74,7 +74,7 @@ const struct ltc_cipher_descriptor rijndael_enc_desc =
     6,
     16, 32, 16, 10,
     SETUP, ECB_ENC, NULL, NULL, ECB_DONE, ECB_KS,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 const struct ltc_cipher_descriptor aes_enc_desc =
@@ -83,7 +83,7 @@ const struct ltc_cipher_descriptor aes_enc_desc =
     6,
     16, 32, 16, 10,
     SETUP, ECB_ENC, NULL, NULL, ECB_DONE, ECB_KS,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 #endif
diff --git a/src/ciphers/anubis.c b/src/ciphers/anubis.c
index 226a190..c3b3c2f 100644
--- a/src/ciphers/anubis.c
+++ b/src/ciphers/anubis.c
@@ -29,7 +29,7 @@ const struct ltc_cipher_descriptor anubis_desc = {
    &anubis_test,
    &anubis_done,
    &anubis_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 #define MIN_N           4
diff --git a/src/ciphers/blowfish.c b/src/ciphers/blowfish.c
index cbe6942..9a78733 100644
--- a/src/ciphers/blowfish.c
+++ b/src/ciphers/blowfish.c
@@ -27,7 +27,7 @@ const struct ltc_cipher_descriptor blowfish_desc =
     &blowfish_test,
     &blowfish_done,
     &blowfish_keysize,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 static const ulong32 ORIG_P[16 + 2] = {
diff --git a/src/ciphers/camellia.c b/src/ciphers/camellia.c
index 3497cfa..c152ff7 100644
--- a/src/ciphers/camellia.c
+++ b/src/ciphers/camellia.c
@@ -28,7 +28,7 @@ const struct ltc_cipher_descriptor camellia_desc = {
    &camellia_test,
    &camellia_done,
    &camellia_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 static const ulong32 SP1110[] = {
diff --git a/src/ciphers/cast5.c b/src/ciphers/cast5.c
index 817ec5a..f4f9154 100644
--- a/src/ciphers/cast5.c
+++ b/src/ciphers/cast5.c
@@ -27,7 +27,7 @@ const struct ltc_cipher_descriptor cast5_desc = {
    &cast5_test,
    &cast5_done,
    &cast5_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 static const ulong32 S1[256] = {
diff --git a/src/ciphers/des.c b/src/ciphers/des.c
index b706b07..cd343b3 100644
--- a/src/ciphers/des.c
+++ b/src/ciphers/des.c
@@ -31,7 +31,7 @@ const struct ltc_cipher_descriptor des_desc =
     &des_test,
     &des_done,
     &des_keysize,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 const struct ltc_cipher_descriptor des3_desc =
@@ -45,7 +45,7 @@ const struct ltc_cipher_descriptor des3_desc =
     &des3_test,
     &des3_done,
     &des3_keysize,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 static const ulong32 bytebit[8] =
diff --git a/src/ciphers/kasumi.c b/src/ciphers/kasumi.c
index c611331..61369e0 100644
--- a/src/ciphers/kasumi.c
+++ b/src/ciphers/kasumi.c
@@ -33,7 +33,7 @@ const struct ltc_cipher_descriptor kasumi_desc = {
    &kasumi_test,
    &kasumi_done,
    &kasumi_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 static u16 FI( u16 in, u16 subkey )
diff --git a/src/ciphers/khazad.c b/src/ciphers/khazad.c
index 285e8b1..1cea03c 100644
--- a/src/ciphers/khazad.c
+++ b/src/ciphers/khazad.c
@@ -28,7 +28,7 @@ const struct ltc_cipher_descriptor khazad_desc = {
    &khazad_test,
    &khazad_done,
    &khazad_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 #define R      8
diff --git a/src/ciphers/kseed.c b/src/ciphers/kseed.c
index e8f0fa8..003074c 100644
--- a/src/ciphers/kseed.c
+++ b/src/ciphers/kseed.c
@@ -29,7 +29,7 @@ const struct ltc_cipher_descriptor kseed_desc = {
    &kseed_test,
    &kseed_done,
    &kseed_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 static const ulong32 SS0[256] = {
diff --git a/src/ciphers/multi2.c b/src/ciphers/multi2.c
index 65249a3..d1e4a6c 100644
--- a/src/ciphers/multi2.c
+++ b/src/ciphers/multi2.c
@@ -116,7 +116,7 @@ const struct ltc_cipher_descriptor multi2_desc = {
    &multi2_test,
    &multi2_done,
    &multi2_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 int  multi2_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
diff --git a/src/ciphers/noekeon.c b/src/ciphers/noekeon.c
index 40c0711..f748d3e 100644
--- a/src/ciphers/noekeon.c
+++ b/src/ciphers/noekeon.c
@@ -27,7 +27,7 @@ const struct ltc_cipher_descriptor noekeon_desc =
     &noekeon_test,
     &noekeon_done,
     &noekeon_keysize,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 static const ulong32 RC[] = {
diff --git a/src/ciphers/rc2.c b/src/ciphers/rc2.c
index 87ccb6d..dbe5696 100644
--- a/src/ciphers/rc2.c
+++ b/src/ciphers/rc2.c
@@ -36,7 +36,7 @@ const struct ltc_cipher_descriptor rc2_desc = {
    &rc2_test,
    &rc2_done,
    &rc2_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 /* 256-entry permutation table, probably derived somehow from pi */
diff --git a/src/ciphers/rc5.c b/src/ciphers/rc5.c
index b267a5a..bd964e2 100644
--- a/src/ciphers/rc5.c
+++ b/src/ciphers/rc5.c
@@ -29,7 +29,7 @@ const struct ltc_cipher_descriptor rc5_desc =
     &rc5_test,
     &rc5_done,
     &rc5_keysize,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 static const ulong32 stab[50] = {
diff --git a/src/ciphers/rc6.c b/src/ciphers/rc6.c
index 611c00c..48d413d 100644
--- a/src/ciphers/rc6.c
+++ b/src/ciphers/rc6.c
@@ -28,7 +28,7 @@ const struct ltc_cipher_descriptor rc6_desc =
     &rc6_test,
     &rc6_done,
     &rc6_keysize,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 static const ulong32 stab[44] = {
diff --git a/src/ciphers/safer/safer.c b/src/ciphers/safer/safer.c
index 434a7db..865eee3 100644
--- a/src/ciphers/safer/safer.c
+++ b/src/ciphers/safer/safer.c
@@ -45,7 +45,7 @@ const struct ltc_cipher_descriptor
    &safer_k64_test,
    &safer_done,
    &safer_64_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
    },
 
    safer_sk64_desc = {
@@ -57,7 +57,7 @@ const struct ltc_cipher_descriptor
    &safer_sk64_test,
    &safer_done,
    &safer_64_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
    },
 
    safer_k128_desc = {
@@ -69,7 +69,7 @@ const struct ltc_cipher_descriptor
    &safer_sk128_test,
    &safer_done,
    &safer_128_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
    },
 
    safer_sk128_desc = {
@@ -81,7 +81,7 @@ const struct ltc_cipher_descriptor
    &safer_sk128_test,
    &safer_done,
    &safer_128_keysize,
-   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+   NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
    };
 
 /******************* Constants ************************************************/
diff --git a/src/ciphers/safer/saferp.c b/src/ciphers/safer/saferp.c
index 27580b8..e5f8bf3 100644
--- a/src/ciphers/safer/saferp.c
+++ b/src/ciphers/safer/saferp.c
@@ -31,7 +31,7 @@ const struct ltc_cipher_descriptor saferp_desc =
     &saferp_test,
     &saferp_done,
     &saferp_keysize,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 /* ROUND(b,i)
diff --git a/src/ciphers/skipjack.c b/src/ciphers/skipjack.c
index 9b2e101..4333a9f 100644
--- a/src/ciphers/skipjack.c
+++ b/src/ciphers/skipjack.c
@@ -28,7 +28,7 @@ const struct ltc_cipher_descriptor skipjack_desc =
     &skipjack_test,
     &skipjack_done,
     &skipjack_keysize,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 static const unsigned char sbox[256] = {
diff --git a/src/ciphers/twofish/twofish.c b/src/ciphers/twofish/twofish.c
index be6c7d5..b443a7c 100644
--- a/src/ciphers/twofish/twofish.c
+++ b/src/ciphers/twofish/twofish.c
@@ -35,7 +35,7 @@ const struct ltc_cipher_descriptor twofish_desc =
     &twofish_test,
     &twofish_done,
     &twofish_keysize,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 /* the two polynomials */
diff --git a/src/ciphers/xtea.c b/src/ciphers/xtea.c
index 963824d..4b3b52b 100644
--- a/src/ciphers/xtea.c
+++ b/src/ciphers/xtea.c
@@ -28,7 +28,7 @@ const struct ltc_cipher_descriptor xtea_desc =
     &xtea_test,
     &xtea_done,
     &xtea_keysize,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
 };
 
 int xtea_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
diff --git a/src/headers/tomcrypt_cipher.h b/src/headers/tomcrypt_cipher.h
index edf25c0..da3a6b7 100644
--- a/src/headers/tomcrypt_cipher.h
+++ b/src/headers/tomcrypt_cipher.h
@@ -553,6 +553,36 @@ extern struct ltc_cipher_descriptor {
        const unsigned char *key, unsigned long keylen,
        const unsigned char *in,  unsigned long inlen,
              unsigned char *out, unsigned long *outlen);
+
+   /** Accelerated XTS encryption
+       @param pt      Plaintext
+       @param ct      Ciphertext
+       @param blocks  The number of complete blocks to process
+       @param tweak   The 128-bit encryption tweak (input/output).
+                      The tweak should not be encrypted on input, but
+                      next tweak will be copied encrypted on output.
+       @param skey1   The first scheduled key context
+       @param skey2   The second scheduled key context
+       @return CRYPT_OK if successful
+    */
+    int (*accel_xts_encrypt)(const unsigned char *pt, unsigned char *ct,
+        unsigned long blocks, unsigned char *tweak, symmetric_key *skey1,
+        symmetric_key *skey2);
+
+    /** Accelerated XTS decryption
+        @param ct      Ciphertext
+        @param pt      Plaintext
+        @param blocks  The number of complete blocks to process
+        @param tweak   The 128-bit encryption tweak (input/output).
+                       The tweak should not be encrypted on input, but
+                       next tweak will be copied encrypted on output.
+        @param skey1   The first scheduled key context
+        @param skey2   The second scheduled key context
+        @return CRYPT_OK if successful
+     */
+     int (*accel_xts_decrypt)(const unsigned char *ct, unsigned char *pt,
+         unsigned long blocks, unsigned char *tweak, symmetric_key *skey1,
+         symmetric_key *skey2);
 } cipher_descriptor[];
 
 #ifdef LTC_BLOWFISH
diff --git a/src/misc/crypt/crypt_cipher_descriptor.c b/src/misc/crypt/crypt_cipher_descriptor.c
index 20aac57..2e35787 100644
--- a/src/misc/crypt/crypt_cipher_descriptor.c
+++ b/src/misc/crypt/crypt_cipher_descriptor.c
@@ -16,7 +16,7 @@
 */
 
 struct ltc_cipher_descriptor cipher_descriptor[TAB_SIZE] = {
-{ NULL, 0, 0, 0, 0, 0, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL }
+{ NULL, 0, 0, 0, 0, 0, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL }
  };
 
 LTC_MUTEX_GLOBAL(ltc_cipher_mutex)
diff --git a/src/modes/xts/xts_decrypt.c b/src/modes/xts/xts_decrypt.c
index f73770d..453ea00 100644
--- a/src/modes/xts/xts_decrypt.c
+++ b/src/modes/xts/xts_decrypt.c
@@ -87,22 +87,36 @@ static int tweak_uncrypt(const unsigned char *C, unsigned char *P, unsigned char
       return CRYPT_INVALID_ARG;
    }
 
-   /* encrypt the tweak */
-   if ((err = cipher_descriptor[xts->cipher].ecb_encrypt(tweak, T, &xts->key2)) != CRYPT_OK) {
-      return err;
-   }
-
-   /* for i = 0 to m-2 do */
    if (mo == 0) {
       lim = m;
    } else {
       lim = m - 1;
    }
 
-   for (i = 0; i < lim; i++) {
-      err = tweak_uncrypt(ct, pt, T, xts);
-      ct += 16;
-      pt += 16;
+   if (cipher_descriptor[xts->cipher].accel_xts_encrypt && lim > 0) {
+
+	   /* use accelerated decryption for whole blocks */
+	   if ((err = cipher_descriptor[xts->cipher].accel_xts_decrypt(ct, pt,
+			lim, tweak, &xts->key1, &xts->key2) != CRYPT_OK)) {
+	      return err;
+	   }
+	   ct += lim * 16;
+	   pt += lim * 16;
+
+	   /* tweak is encrypted on output */
+	   XMEMCPY(T, tweak, sizeof(T));
+   } else {
+      /* encrypt the tweak */
+      if ((err = cipher_descriptor[xts->cipher].ecb_encrypt(tweak, T,
+			&xts->key2)) != CRYPT_OK) {
+	 return err;
+      }
+
+      for (i = 0; i < lim; i++) {
+	 err = tweak_uncrypt(ct, pt, T, xts);
+	 ct += 16;
+	 pt += 16;
+      }
    }
    
    /* if ptlen not divide 16 then */
@@ -131,7 +145,8 @@ static int tweak_uncrypt(const unsigned char *C, unsigned char *P, unsigned char
    }
 
    /* Decrypt the tweak back */
-   if ((err = cipher_descriptor[xts->cipher].ecb_decrypt(T, tweak, &xts->key2)) != CRYPT_OK) {
+   if ((err = cipher_descriptor[xts->cipher].ecb_decrypt(T, tweak,
+			&xts->key2)) != CRYPT_OK) {
       return err;
    }
 
diff --git a/src/modes/xts/xts_encrypt.c b/src/modes/xts/xts_encrypt.c
index 6474b13..136538b 100644
--- a/src/modes/xts/xts_encrypt.c
+++ b/src/modes/xts/xts_encrypt.c
@@ -85,27 +85,42 @@ int xts_encrypt(
    m  = ptlen >> 4;
    mo = ptlen & 15;
 
-	   /* must have at least one full block */
+   /* must have at least one full block */
    if (m == 0) {
       return CRYPT_INVALID_ARG;
    }
 
-   /* encrypt the tweak */
-   if ((err = cipher_descriptor[xts->cipher].ecb_encrypt(tweak, T, &xts->key2)) != CRYPT_OK) {
-      return err;
-   }
-
-   /* for i = 0 to m-2 do */
    if (mo == 0) {
       lim = m;
    } else {
       lim = m - 1;
    }
 
-   for (i = 0; i < lim; i++) {
-      err = tweak_crypt(pt, ct, T, xts);
-      ct += 16;
-      pt += 16;
+   if (cipher_descriptor[xts->cipher].accel_xts_encrypt && lim > 0) {
+
+      /* use accelerated encryption for whole blocks */
+      if ((err = cipher_descriptor[xts->cipher].accel_xts_encrypt(pt, ct, lim,
+			tweak, &xts->key1, &xts->key2) != CRYPT_OK)) {
+	 return err;
+      }
+      ct += lim * 16;
+      pt += lim * 16;
+
+      /* tweak is encrypted on output */
+      XMEMCPY(T, tweak, sizeof(T));
+   } else {
+
+      /* encrypt the tweak */
+      if ((err = cipher_descriptor[xts->cipher].ecb_encrypt(tweak, T,
+			&xts->key2)) != CRYPT_OK) {
+	 return err;
+      }
+
+      for (i = 0; i < lim; i++) {
+	 err = tweak_crypt(pt, ct, T, xts);
+	 ct += 16;
+	 pt += 16;
+      }
    }
    
    /* if ptlen not divide 16 then */
@@ -132,7 +147,8 @@ int xts_encrypt(
    }
 
    /* Decrypt the tweak back */
-   if ((err = cipher_descriptor[xts->cipher].ecb_decrypt(T, tweak, &xts->key2)) != CRYPT_OK) {
+   if ((err = cipher_descriptor[xts->cipher].ecb_decrypt(T, tweak,
+		&xts->key2)) != CRYPT_OK) {
       return err;
    }