cipher: Add wrappers for AES-XTS

AES-XTS does not support multipart use as it can only operate on an entire
sector at a time.
diff --git a/library/cipher.c b/library/cipher.c
index a5cd61c..4f12b72 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -440,6 +440,27 @@
     }
 #endif /* MBEDTLS_CIPHER_MODE_CTR */
 
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    if( ctx->cipher_info->mode == MBEDTLS_MODE_XTS )
+    {
+        if ( ctx->unprocessed_len ) {
+            /* We can only process an entire sector at a time. */
+            return( MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE );
+        }
+
+        ret = ctx->cipher_info->base->xts_func( ctx->cipher_ctx,
+                ctx->operation, ilen, ctx->iv, input, output );
+        if( ret != 0 )
+        {
+            return( ret );
+        }
+
+        *olen = ilen;
+
+        return( 0 );
+    }
+#endif /* MBEDTLS_CIPHER_MODE_XTS */
+
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     if( ctx->cipher_info->mode == MBEDTLS_MODE_STREAM )
     {
@@ -641,6 +662,7 @@
     if( MBEDTLS_MODE_CFB == ctx->cipher_info->mode ||
         MBEDTLS_MODE_CTR == ctx->cipher_info->mode ||
         MBEDTLS_MODE_GCM == ctx->cipher_info->mode ||
+        MBEDTLS_MODE_XTS == ctx->cipher_info->mode ||
         MBEDTLS_MODE_STREAM == ctx->cipher_info->mode )
     {
         return( 0 );
diff --git a/library/cipher_wrap.c b/library/cipher_wrap.c
index dc76af8..070f1d8 100644
--- a/library/cipher_wrap.c
+++ b/library/cipher_wrap.c
@@ -148,6 +148,33 @@
 }
 #endif /* MBEDTLS_CIPHER_MODE_CTR */
 
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+static int aes_crypt_xts_wrap( void *ctx, mbedtls_operation_t operation,
+                               size_t length,
+                               const unsigned char data_unit[16],
+                               const unsigned char *input,
+                               unsigned char *output )
+{
+    mbedtls_aes_xts_context *xts_ctx = ctx;
+    int mode;
+
+    switch (operation)
+    {
+        case MBEDTLS_ENCRYPT:
+            mode = MBEDTLS_AES_ENCRYPT;
+            break;
+        case MBEDTLS_DECRYPT:
+            mode = MBEDTLS_AES_DECRYPT;
+            break;
+        default:
+            return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
+    }
+
+    return mbedtls_aes_crypt_xts( xts_ctx, mode, length,
+                                  data_unit, input, output );
+}
+#endif /* MBEDTLS_CIPHER_MODE_XTS */
+
 static int aes_setkey_dec_wrap( void *ctx, const unsigned char *key,
                                 unsigned int key_bitlen )
 {
@@ -190,6 +217,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     aes_crypt_ctr_wrap,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     NULL,
 #endif
@@ -337,6 +367,89 @@
 };
 #endif /* MBEDTLS_CIPHER_MODE_CTR */
 
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+static int xts_aes_setkey_enc_wrap( void *ctx, const unsigned char *key,
+                                    unsigned int key_bitlen )
+{
+    mbedtls_aes_xts_context *xts_ctx = ctx;
+    return( mbedtls_aes_xts_setkey_enc( xts_ctx, key, key_bitlen ) );
+}
+
+static int xts_aes_setkey_dec_wrap( void *ctx, const unsigned char *key,
+                                    unsigned int key_bitlen )
+{
+    mbedtls_aes_xts_context *xts_ctx = ctx;
+    return( mbedtls_aes_xts_setkey_dec( xts_ctx, key, key_bitlen ) );
+}
+
+static void *xts_aes_ctx_alloc( void )
+{
+    mbedtls_aes_xts_context *xts_ctx = mbedtls_calloc( 1, sizeof( *xts_ctx ) );
+
+    if( xts_ctx )
+        mbedtls_aes_xts_init( xts_ctx );
+
+    return( xts_ctx );
+}
+
+static void xts_aes_ctx_free( void *ctx )
+{
+    mbedtls_aes_xts_context *xts_ctx = ctx;
+
+    if ( !xts_ctx )
+        return;
+
+    mbedtls_aes_xts_free( xts_ctx );
+    mbedtls_free( xts_ctx );
+}
+
+static const mbedtls_cipher_base_t xts_aes_info = {
+    MBEDTLS_CIPHER_ID_AES,
+    NULL,
+#if defined(MBEDTLS_CIPHER_MODE_CBC)
+    NULL,
+#endif
+#if defined(MBEDTLS_CIPHER_MODE_CFB)
+    NULL,
+#endif
+#if defined(MBEDTLS_CIPHER_MODE_CTR)
+    NULL,
+#endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    aes_crypt_xts_wrap,
+#endif
+#if defined(MBEDTLS_CIPHER_MODE_STREAM)
+    NULL,
+#endif
+    xts_aes_setkey_enc_wrap,
+    xts_aes_setkey_dec_wrap,
+    xts_aes_ctx_alloc,
+    xts_aes_ctx_free
+};
+
+static const mbedtls_cipher_info_t aes_128_xts_info = {
+    MBEDTLS_CIPHER_AES_128_XTS,
+    MBEDTLS_MODE_XTS,
+    256,
+    "AES-128-XTS",
+    16,
+    0,
+    16,
+    &xts_aes_info
+};
+
+static const mbedtls_cipher_info_t aes_256_xts_info = {
+    MBEDTLS_CIPHER_AES_256_XTS,
+    MBEDTLS_MODE_XTS,
+    512,
+    "AES-256-XTS",
+    16,
+    0,
+    16,
+    &xts_aes_info
+};
+#endif /* MBEDTLS_CIPHER_MODE_XTS */
+
 #if defined(MBEDTLS_GCM_C)
 static int gcm_aes_setkey_wrap( void *ctx, const unsigned char *key,
                                 unsigned int key_bitlen )
@@ -357,6 +470,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     NULL,
 #endif
@@ -420,6 +536,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     NULL,
 #endif
@@ -547,6 +666,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     camellia_crypt_ctr_wrap,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     NULL,
 #endif
@@ -714,6 +836,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     NULL,
 #endif
@@ -777,6 +902,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     NULL,
 #endif
@@ -953,6 +1081,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     NULL,
 #endif
@@ -998,6 +1129,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     NULL,
 #endif
@@ -1043,6 +1177,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     NULL,
 #endif
@@ -1152,6 +1289,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     blowfish_crypt_ctr_wrap,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     NULL,
 #endif
@@ -1262,6 +1402,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     arc4_crypt_stream_wrap,
 #endif
@@ -1325,6 +1468,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_STREAM)
     null_crypt_stream,
 #endif
@@ -1367,6 +1513,10 @@
     { MBEDTLS_CIPHER_AES_192_CTR,          &aes_192_ctr_info },
     { MBEDTLS_CIPHER_AES_256_CTR,          &aes_256_ctr_info },
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+    { MBEDTLS_CIPHER_AES_128_XTS,          &aes_128_xts_info },
+    { MBEDTLS_CIPHER_AES_256_XTS,          &aes_256_xts_info },
+#endif
 #if defined(MBEDTLS_GCM_C)
     { MBEDTLS_CIPHER_AES_128_GCM,          &aes_128_gcm_info },
     { MBEDTLS_CIPHER_AES_192_GCM,          &aes_192_gcm_info },