Add cipher abstraction and test cases for OFB block mode

Adds OFB as additional block mode in the cipher abstraction, and additional
test cases for that block mode.
diff --git a/ChangeLog b/ChangeLog
index 4fbdb3d..80574f7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,8 @@
 Features
    * Add support for ARIA cipher (RFC 5794) and associated TLS ciphersuites
      (RFC 6209). Disabled by default, see MBEDTLS_ARIA_C in config.h
+   * Add additional block mode, OFB (Output Feedback), to the AES module and
+     cipher abstraction module.
 
 API Changes
    * Extend the platform module with a util component that contains
diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index 46b3bdf..0db8fc8 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -164,6 +164,9 @@
     MBEDTLS_CIPHER_ARIA_128_CCM,         /**< Aria cipher with 128-bit key and CCM mode. */
     MBEDTLS_CIPHER_ARIA_192_CCM,         /**< Aria cipher with 192-bit key and CCM mode. */
     MBEDTLS_CIPHER_ARIA_256_CCM,         /**< Aria cipher with 256-bit key and CCM mode. */
+    MBEDTLS_CIPHER_AES_128_OFB,
+    MBEDTLS_CIPHER_AES_192_OFB,
+    MBEDTLS_CIPHER_AES_256_OFB
 } mbedtls_cipher_type_t;
 
 /** Supported cipher modes. */
diff --git a/include/mbedtls/cipher_internal.h b/include/mbedtls/cipher_internal.h
index 969ff9c..e761a9e 100644
--- a/include/mbedtls/cipher_internal.h
+++ b/include/mbedtls/cipher_internal.h
@@ -59,11 +59,20 @@
 
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     /** Encrypt using CFB (Full length) */
+
     int (*cfb_func)( void *ctx, mbedtls_operation_t mode, size_t length, size_t *iv_off,
                      unsigned char *iv, const unsigned char *input,
                      unsigned char *output );
 #endif
 
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    /** Encrypt using OFB (Full length) */
+    int (*ofb_func)( void *ctx, size_t length, size_t *iv_off,
+                     unsigned char *iv,
+                     const unsigned char *input,
+                     unsigned char *output );
+#endif
+
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     /** Encrypt using CTR */
     int (*ctr_func)( void *ctx, size_t length, size_t *nc_off,
diff --git a/library/cipher.c b/library/cipher.c
index a5cd61c..2c599e5 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -191,10 +191,11 @@
     ctx->operation = operation;
 
     /*
-     * For CFB and CTR mode always use the encryption key schedule
+     * For OFB, CFB and CTR mode always use the encryption key schedule
      */
     if( MBEDTLS_ENCRYPT == operation ||
         MBEDTLS_MODE_CFB == ctx->cipher_info->mode ||
+        MBEDTLS_MODE_OFB == ctx->cipher_info->mode ||
         MBEDTLS_MODE_CTR == ctx->cipher_info->mode )
     {
         return ctx->cipher_info->base->setkey_enc_func( ctx->cipher_ctx, key,
@@ -424,6 +425,21 @@
     }
 #endif /* MBEDTLS_CIPHER_MODE_CFB */
 
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    if( ctx->cipher_info->mode == MBEDTLS_MODE_OFB )
+    {
+        if( 0 != ( ret = ctx->cipher_info->base->ofb_func( ctx->cipher_ctx,
+                ilen, &ctx->unprocessed_len, ctx->iv, input, output ) ) )
+        {
+            return( ret );
+        }
+
+        *olen = ilen;
+
+        return( 0 );
+    }
+#endif /* MBEDTLS_CIPHER_MODE_OFB */
+
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     if( ctx->cipher_info->mode == MBEDTLS_MODE_CTR )
     {
@@ -639,6 +655,7 @@
     *olen = 0;
 
     if( MBEDTLS_MODE_CFB == ctx->cipher_info->mode ||
+        MBEDTLS_MODE_OFB == ctx->cipher_info->mode ||
         MBEDTLS_MODE_CTR == ctx->cipher_info->mode ||
         MBEDTLS_MODE_GCM == ctx->cipher_info->mode ||
         MBEDTLS_MODE_STREAM == ctx->cipher_info->mode )
diff --git a/library/cipher_wrap.c b/library/cipher_wrap.c
index a9ef819..ef47037 100644
--- a/library/cipher_wrap.c
+++ b/library/cipher_wrap.c
@@ -142,6 +142,15 @@
 }
 #endif /* MBEDTLS_CIPHER_MODE_CFB */
 
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+static int aes_crypt_ofb_wrap( void *ctx, size_t length, size_t *iv_off,
+        unsigned char *iv, const unsigned char *input, unsigned char *output )
+{
+    return mbedtls_aes_crypt_ofb( (mbedtls_aes_context *) ctx, length, iv_off,
+                                    iv, input, output );
+}
+#endif /* MBEDTLS_CIPHER_MODE_OFB */
+
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
 static int aes_crypt_ctr_wrap( void *ctx, size_t length, size_t *nc_off,
         unsigned char *nonce_counter, unsigned char *stream_block,
@@ -191,6 +200,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     aes_crypt_cfb128_wrap,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    aes_crypt_ofb_wrap,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     aes_crypt_ctr_wrap,
 #endif
@@ -306,6 +318,41 @@
 };
 #endif /* MBEDTLS_CIPHER_MODE_CFB */
 
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+static const mbedtls_cipher_info_t aes_128_ofb_info = {
+    MBEDTLS_CIPHER_AES_128_OFB,
+    MBEDTLS_MODE_OFB,
+    128,
+    "AES-128-OFB",
+    16,
+    0,
+    16,
+    &aes_info
+};
+
+static const mbedtls_cipher_info_t aes_192_ofb_info = {
+    MBEDTLS_CIPHER_AES_192_OFB,
+    MBEDTLS_MODE_OFB,
+    192,
+    "AES-192-OFB",
+    16,
+    0,
+    16,
+    &aes_info
+};
+
+static const mbedtls_cipher_info_t aes_256_ofb_info = {
+    MBEDTLS_CIPHER_AES_256_OFB,
+    MBEDTLS_MODE_OFB,
+    256,
+    "AES-256-OFB",
+    16,
+    0,
+    16,
+    &aes_info
+};
+#endif /* MBEDTLS_CIPHER_MODE_OFB */
+
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
 static const mbedtls_cipher_info_t aes_128_ctr_info = {
     MBEDTLS_CIPHER_AES_128_CTR,
@@ -358,6 +405,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -421,6 +471,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -548,6 +601,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     camellia_crypt_cfb128_wrap,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     camellia_crypt_ctr_wrap,
 #endif
@@ -715,6 +771,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -778,6 +837,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -1312,6 +1374,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -1357,6 +1422,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -1402,6 +1470,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -1511,6 +1582,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     blowfish_crypt_cfb64_wrap,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     blowfish_crypt_ctr_wrap,
 #endif
@@ -1621,6 +1695,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -1724,6 +1801,11 @@
     { MBEDTLS_CIPHER_AES_192_CFB128,       &aes_192_cfb128_info },
     { MBEDTLS_CIPHER_AES_256_CFB128,       &aes_256_cfb128_info },
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    { MBEDTLS_CIPHER_AES_128_OFB,          &aes_128_ofb_info },
+    { MBEDTLS_CIPHER_AES_192_OFB,          &aes_192_ofb_info },
+    { MBEDTLS_CIPHER_AES_256_OFB,          &aes_256_ofb_info },
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     { MBEDTLS_CIPHER_AES_128_CTR,          &aes_128_ctr_info },
     { MBEDTLS_CIPHER_AES_192_CTR,          &aes_192_ctr_info },
diff --git a/tests/suites/test_suite_cipher.aes.data b/tests/suites/test_suite_cipher.aes.data
index e8e9a15..e34b70d 100644
--- a/tests/suites/test_suite_cipher.aes.data
+++ b/tests/suites/test_suite_cipher.aes.data
@@ -474,6 +474,110 @@
 depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_CFB
 enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_CFB128:128:16:16:-1:16:16:16:16
 
+AES-128 OFB - Encrypt and decrypt 0 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:0:-1
+
+AES-128 OFB - Encrypt and decrypt 1 byte
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:1:-1
+
+AES-128 OFB - Encrypt and decrypt 2 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:2:-1
+
+AES-128 OFB - Encrypt and decrypt 7 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:7:-1
+
+AES-128 OFB - Encrypt and decrypt 8 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:8:-1
+
+AES-128 OFB - Encrypt and decrypt 9 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:9:-1
+
+AES-128 OFB - Encrypt and decrypt 15 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:15:-1
+
+AES-128 OFB - Encrypt and decrypt 16 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:16:-1
+
+AES-128 OFB - Encrypt and decrypt 17 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:17:-1
+
+AES-128 OFB - Encrypt and decrypt 31 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:31:-1
+
+AES-128 OFB - Encrypt and decrypt 32 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:32:-1
+
+AES-128 OFB - Encrypt and decrypt 32 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:33:-1
+
+AES-128 OFB - Encrypt and decrypt 47 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:47:-1
+
+AES-128 OFB - Encrypt and decrypt 48 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:48:-1
+
+AES-128 OFB - Encrypt and decrypt 49 bytes
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf:MBEDTLS_CIPHER_AES_128_OFB:"AES-128-OFB":128:49:-1
+
+AES-128 OFB - Encrypt and decrypt 0 bytes in multiple parts
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:0:0:-1:0:0:0:0
+
+AES-128 OFB - Encrypt and decrypt 1 bytes in multiple parts 1
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:1:0:-1:1:0:1:0
+
+AES-128 OFB - Encrypt and decrypt 1 bytes in multiple parts 2
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:0:1:-1:0:1:0:1
+
+AES-128 OFB - Encrypt and decrypt 16 bytes in multiple parts 1
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:16:0:-1:16:0:16:0
+
+AES-128 OFB - Encrypt and decrypt 16 bytes in multiple parts 2
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:0:16:-1:0:16:0:16
+
+AES-128 OFB - Encrypt and decrypt 16 bytes in multiple parts 3
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:1:15:-1:1:15:1:15
+
+AES-128 OFB - Encrypt and decrypt 16 bytes in multiple parts 4
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:15:1:-1:15:1:15:1
+
+AES-128 OFB - Encrypt and decrypt 22 bytes in multiple parts 1
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:15:7:-1:15:7:15:7
+
+AES-128 OFB - Encrypt and decrypt 22 bytes in multiple parts 2
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:16:6:-1:16:6:16:6
+
+AES-128 OFB - Encrypt and decrypt 23 bytes in multiple parts 1
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:17:6:-1:17:6:17:6
+
+AES-128 OFB - Encrypt and decrypt 32 bytes in multiple parts 1
+depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_OFB
+enc_dec_buf_multipart:MBEDTLS_CIPHER_AES_128_OFB:128:16:16:-1:16:16:16:16
+
 AES-128 CTR - Encrypt and decrypt 0 bytes
 depends_on:MBEDTLS_AES_C:MBEDTLS_CIPHER_MODE_CTR
 enc_dec_buf:MBEDTLS_CIPHER_AES_128_CTR:"AES-128-CTR":128:0:-1