diff --git a/ChangeLog b/ChangeLog
index cf7d13a..25f3b32 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -14,7 +14,9 @@
      facilitate testing and maintenance.
 
 Features
-    * Implement HKDF per RFC 5869. Contributed by Thomas Fossati.
+   * Implement HKDF per RFC 5869. Contributed by Thomas Fossati.
+   * Add additional block mode, OFB (Output Feedback), to the AES module and
+     cipher abstraction module.
 
 = mbed TLS 2.9.0 branch released 2018-04-30
 
diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index e0fc238..7632ac0 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -295,6 +295,46 @@
                     unsigned char *output );
 #endif /*MBEDTLS_CIPHER_MODE_CFB */
 
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+/**
+ * \brief This function performs an AES-OFB (Output Feedback Mode) encryption
+ *        or decryption operation.
+ *
+ *        For OFB, you must set up the context with mbedtls_aes_setkey_enc(),
+ *        regardless of whether you are performing an encryption or decryption
+ *        operation. This is because OFB mode uses the same key schedule for
+ *        encryption and decryption.
+ *
+ *        The OFB operation is identical for encryption or decryption, therefore
+ *        no operation mode needs to be specified.
+ *
+ * \note  Upon exit, the content of the IV is updated so that you can
+ *        call the same function again on the next
+ *        block(s) of data and get the same result as if it was
+ *        encrypted in one call. This allows a "streaming" usage.
+ *        If you need to retain the contents of the
+ *        IV, you must either save it manually or use the cipher
+ *        module instead.
+ *
+ *
+ * \param ctx      The AES context to use for encryption or decryption.
+ * \param length   The length of the input data.
+ * \param iv_off   The offset in IV (updated after use).
+ * \param iv       The initialization vector (updated after use).
+ * \param input    The buffer holding the input data.
+ * \param output   The buffer holding the output data.
+ *
+ * \return         \c 0 on success.
+ */
+int mbedtls_aes_crypt_ofb( mbedtls_aes_context *ctx,
+                       size_t length,
+                       size_t *iv_off,
+                       unsigned char iv[16],
+                       const unsigned char *input,
+                       unsigned char *output );
+
+#endif /* MBEDTLS_CIPHER_MODE_OFB */
+
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
 /**
  * \brief      This function performs an AES-CTR encryption or decryption
diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index 3ee2ab7..bef5f65 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -145,6 +145,9 @@
     MBEDTLS_CIPHER_CAMELLIA_128_CCM,     /**< Camellia cipher with 128-bit CCM mode. */
     MBEDTLS_CIPHER_CAMELLIA_192_CCM,     /**< Camellia cipher with 192-bit CCM mode. */
     MBEDTLS_CIPHER_CAMELLIA_256_CCM,     /**< Camellia cipher with 256-bit CCM mode. */
+    MBEDTLS_CIPHER_AES_128_OFB,          /**< AES 128-bit cipher in OFB mode. */
+    MBEDTLS_CIPHER_AES_192_OFB,          /**< AES 192-bit cipher in OFB mode. */
+    MBEDTLS_CIPHER_AES_256_OFB,          /**< AES 256-bit cipher in OFB mode. */
 } mbedtls_cipher_type_t;
 
 /** Supported cipher modes. */
@@ -153,7 +156,7 @@
     MBEDTLS_MODE_ECB,                    /**< The ECB cipher mode. */
     MBEDTLS_MODE_CBC,                    /**< The CBC cipher mode. */
     MBEDTLS_MODE_CFB,                    /**< The CFB cipher mode. */
-    MBEDTLS_MODE_OFB,                    /**< The OFB cipher mode - unsupported. */
+    MBEDTLS_MODE_OFB,                    /**< The OFB cipher mode. */
     MBEDTLS_MODE_CTR,                    /**< The CTR cipher mode. */
     MBEDTLS_MODE_GCM,                    /**< The GCM cipher mode. */
     MBEDTLS_MODE_STREAM,                 /**< The stream cipher mode. */
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/include/mbedtls/config.h b/include/mbedtls/config.h
index 9047a64..86cb6d1 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -496,6 +496,13 @@
 #define MBEDTLS_CIPHER_MODE_CBC
 
 /**
+ * \def MBEDTLS_CIPHER_MODE_OFB
+ *
+ * Enable Output Feedback mode (OFB) for symmetric ciphers.
+ */
+#define MBEDTLS_CIPHER_MODE_OFB
+
+/**
  * \def MBEDTLS_CIPHER_MODE_CFB
  *
  * Enable Cipher Feedback mode (CFB) for symmetric ciphers.
diff --git a/library/aes.c b/library/aes.c
index b0aea00..22eb53c 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -1061,7 +1061,41 @@
 
     return( 0 );
 }
-#endif /*MBEDTLS_CIPHER_MODE_CFB */
+#endif /* MBEDTLS_CIPHER_MODE_CFB */
+
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+/*
+ * AES-OFB (Output Feedback Mode) buffer encryption/decryption
+ */
+int mbedtls_aes_crypt_ofb( mbedtls_aes_context *ctx,
+                            size_t length,
+                            size_t *iv_off,
+                            unsigned char iv[16],
+                            const unsigned char *input,
+                            unsigned char *output )
+{
+    int ret = 0;
+    size_t n = *iv_off;
+
+    while( length-- )
+    {
+        if( n == 0 )
+        {
+            ret = mbedtls_aes_crypt_ecb( ctx, MBEDTLS_AES_ENCRYPT, iv, iv );
+            if( ret != 0 )
+                goto exit;
+        }
+        *output++ =  *input++ ^ iv[n];
+
+        n = ( n + 1 ) & 0x0F;
+    }
+
+    *iv_off = n;
+
+exit:
+    return( ret );
+}
+#endif /* MBEDTLS_CIPHER_MODE_OFB */
 
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
 /*
@@ -1215,6 +1249,72 @@
 };
 #endif /* MBEDTLS_CIPHER_MODE_CFB */
 
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+/*
+ * AES-OFB test vectors from:
+ *
+ * http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
+ */
+static const unsigned char aes_test_ofb_key[3][32] =
+{
+    { 0x2B, 0x7E, 0x15, 0x16, 0x28, 0xAE, 0xD2, 0xA6,
+      0xAB, 0xF7, 0x15, 0x88, 0x09, 0xCF, 0x4F, 0x3C },
+    { 0x8E, 0x73, 0xB0, 0xF7, 0xDA, 0x0E, 0x64, 0x52,
+      0xC8, 0x10, 0xF3, 0x2B, 0x80, 0x90, 0x79, 0xE5,
+      0x62, 0xF8, 0xEA, 0xD2, 0x52, 0x2C, 0x6B, 0x7B },
+    { 0x60, 0x3D, 0xEB, 0x10, 0x15, 0xCA, 0x71, 0xBE,
+      0x2B, 0x73, 0xAE, 0xF0, 0x85, 0x7D, 0x77, 0x81,
+      0x1F, 0x35, 0x2C, 0x07, 0x3B, 0x61, 0x08, 0xD7,
+      0x2D, 0x98, 0x10, 0xA3, 0x09, 0x14, 0xDF, 0xF4 }
+};
+
+static const unsigned char aes_test_ofb_iv[16] =
+{
+    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+    0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F
+};
+
+static const unsigned char aes_test_ofb_pt[64] =
+{
+    0x6B, 0xC1, 0xBE, 0xE2, 0x2E, 0x40, 0x9F, 0x96,
+    0xE9, 0x3D, 0x7E, 0x11, 0x73, 0x93, 0x17, 0x2A,
+    0xAE, 0x2D, 0x8A, 0x57, 0x1E, 0x03, 0xAC, 0x9C,
+    0x9E, 0xB7, 0x6F, 0xAC, 0x45, 0xAF, 0x8E, 0x51,
+    0x30, 0xC8, 0x1C, 0x46, 0xA3, 0x5C, 0xE4, 0x11,
+    0xE5, 0xFB, 0xC1, 0x19, 0x1A, 0x0A, 0x52, 0xEF,
+    0xF6, 0x9F, 0x24, 0x45, 0xDF, 0x4F, 0x9B, 0x17,
+    0xAD, 0x2B, 0x41, 0x7B, 0xE6, 0x6C, 0x37, 0x10
+};
+
+static const unsigned char aes_test_ofb_ct[3][64] =
+{
+    { 0x3B, 0x3F, 0xD9, 0x2E, 0xB7, 0x2D, 0xAD, 0x20,
+      0x33, 0x34, 0x49, 0xF8, 0xE8, 0x3C, 0xFB, 0x4A,
+      0x77, 0x89, 0x50, 0x8d, 0x16, 0x91, 0x8f, 0x03,
+      0xf5, 0x3c, 0x52, 0xda, 0xc5, 0x4e, 0xd8, 0x25,
+      0x97, 0x40, 0x05, 0x1e, 0x9c, 0x5f, 0xec, 0xf6,
+      0x43, 0x44, 0xf7, 0xa8, 0x22, 0x60, 0xed, 0xcc,
+      0x30, 0x4c, 0x65, 0x28, 0xf6, 0x59, 0xc7, 0x78,
+      0x66, 0xa5, 0x10, 0xd9, 0xc1, 0xd6, 0xae, 0x5e },
+    { 0xCD, 0xC8, 0x0D, 0x6F, 0xDD, 0xF1, 0x8C, 0xAB,
+      0x34, 0xC2, 0x59, 0x09, 0xC9, 0x9A, 0x41, 0x74,
+      0xfc, 0xc2, 0x8b, 0x8d, 0x4c, 0x63, 0x83, 0x7c,
+      0x09, 0xe8, 0x17, 0x00, 0xc1, 0x10, 0x04, 0x01,
+      0x8d, 0x9a, 0x9a, 0xea, 0xc0, 0xf6, 0x59, 0x6f,
+      0x55, 0x9c, 0x6d, 0x4d, 0xaf, 0x59, 0xa5, 0xf2,
+      0x6d, 0x9f, 0x20, 0x08, 0x57, 0xca, 0x6c, 0x3e,
+      0x9c, 0xac, 0x52, 0x4b, 0xd9, 0xac, 0xc9, 0x2a },
+    { 0xDC, 0x7E, 0x84, 0xBF, 0xDA, 0x79, 0x16, 0x4B,
+      0x7E, 0xCD, 0x84, 0x86, 0x98, 0x5D, 0x38, 0x60,
+      0x4f, 0xeb, 0xdc, 0x67, 0x40, 0xd2, 0x0b, 0x3a,
+      0xc8, 0x8f, 0x6a, 0xd8, 0x2a, 0x4f, 0xb0, 0x8d,
+      0x71, 0xab, 0x47, 0xa0, 0x86, 0xe8, 0x6e, 0xed,
+      0xf3, 0x9d, 0x1c, 0x5b, 0xba, 0x97, 0xc4, 0x08,
+      0x01, 0x26, 0x14, 0x1d, 0x67, 0xf3, 0x7b, 0xe8,
+      0x53, 0x8f, 0x5a, 0x8b, 0xe7, 0x40, 0xe4, 0x84 }
+};
+#endif /* MBEDTLS_CIPHER_MODE_OFB */
+
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
 /*
  * AES-CTR test vectors from:
@@ -1506,6 +1606,69 @@
         mbedtls_printf( "\n" );
 #endif /* MBEDTLS_CIPHER_MODE_CFB */
 
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    /*
+     * OFB mode
+     */
+    for( i = 0; i < 6; i++ )
+    {
+        u = i >> 1;
+        keybits = 128 + u * 64;
+        mode = i & 1;
+
+        if( verbose != 0 )
+            mbedtls_printf( "  AES-OFB-%3d (%s): ", keybits,
+                            ( mode == MBEDTLS_AES_DECRYPT ) ? "dec" : "enc" );
+
+        memcpy( iv,  aes_test_ofb_iv, 16 );
+        memcpy( key, aes_test_ofb_key[u], keybits / 8 );
+
+        offset = 0;
+        ret = mbedtls_aes_setkey_enc( &ctx, key, keybits );
+        /*
+         * AES-192 is an optional feature that may be unavailable when
+         * there is an alternative underlying implementation i.e. when
+         * MBEDTLS_AES_ALT is defined.
+         */
+        if( ret == MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE && keybits == 192 )
+        {
+            mbedtls_printf( "skipped\n" );
+            continue;
+        }
+        else if( ret != 0 )
+        {
+            goto exit;
+        }
+
+        if( mode == MBEDTLS_AES_DECRYPT )
+        {
+            memcpy( buf, aes_test_ofb_ct[u], 64 );
+            aes_tests = aes_test_ofb_pt;
+        }
+        else
+        {
+            memcpy( buf, aes_test_ofb_pt, 64 );
+            aes_tests = aes_test_ofb_ct[u];
+        }
+
+        ret = mbedtls_aes_crypt_ofb( &ctx, 64, &offset, iv, buf, buf );
+        if( ret != 0 )
+            goto exit;
+
+        if( memcmp( buf, aes_tests, 64 ) != 0 )
+        {
+            ret = 1;
+            goto exit;
+        }
+
+        if( verbose != 0 )
+            mbedtls_printf( "passed\n" );
+    }
+
+    if( verbose != 0 )
+        mbedtls_printf( "\n" );
+#endif /* MBEDTLS_CIPHER_MODE_OFB */
+
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     /*
      * CTR mode
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 dc76af8..901a2ca 100644
--- a/library/cipher_wrap.c
+++ b/library/cipher_wrap.c
@@ -138,6 +138,15 @@
 }
 #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,
@@ -187,6 +196,9 @@
 #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
@@ -302,6 +314,41 @@
 };
 #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,
@@ -354,6 +401,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -417,6 +467,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -544,6 +597,9 @@
 #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
@@ -711,6 +767,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -774,6 +833,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -950,6 +1012,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -995,6 +1060,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -1040,6 +1108,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -1149,6 +1220,9 @@
 #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
@@ -1259,6 +1333,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -1322,6 +1399,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     NULL,
 #endif
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    NULL,
+#endif
 #if defined(MBEDTLS_CIPHER_MODE_CTR)
     NULL,
 #endif
@@ -1362,6 +1442,11 @@
     { 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/library/version_features.c b/library/version_features.c
index 1b0f180..b462e42 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -246,6 +246,9 @@
 #if defined(MBEDTLS_CIPHER_MODE_CBC)
     "MBEDTLS_CIPHER_MODE_CBC",
 #endif /* MBEDTLS_CIPHER_MODE_CBC */
+#if defined(MBEDTLS_CIPHER_MODE_OFB)
+    "MBEDTLS_CIPHER_MODE_OFB",
+#endif /* MBEDTLS_CIPHER_MODE_OFB */
 #if defined(MBEDTLS_CIPHER_MODE_CFB)
     "MBEDTLS_CIPHER_MODE_CFB",
 #endif /* MBEDTLS_CIPHER_MODE_CFB */
diff --git a/tests/Makefile b/tests/Makefile
index e127809..9b9aafe 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -46,7 +46,8 @@
 endif
 
 APPS =	test_suite_aes.ecb$(EXEXT)	test_suite_aes.cbc$(EXEXT)	\
-	test_suite_aes.cfb$(EXEXT)	test_suite_aes.rest$(EXEXT)	\
+	test_suite_aes.cfb$(EXEXT)	test_suite_aes.ofb$(EXEXT)	\
+	test_suite_aes.rest$(EXEXT)	\
 	test_suite_arc4$(EXEXT)		test_suite_asn1write$(EXEXT)	\
 	test_suite_base64$(EXEXT)	test_suite_blowfish$(EXEXT)	\
 	test_suite_camellia$(EXEXT)	test_suite_ccm$(EXEXT)		\
@@ -110,6 +111,10 @@
 	echo "  Gen   $@"
 	perl scripts/generate_code.pl suites test_suite_aes test_suite_aes.cfb
 
+test_suite_aes.ofb.c : suites/test_suite_aes.function suites/test_suite_aes.ofb.data scripts/generate_code.pl suites/helpers.function suites/main_test.function
+	echo "  Gen   $@"
+	perl scripts/generate_code.pl suites test_suite_aes test_suite_aes.ofb
+
 test_suite_aes.rest.c : suites/test_suite_aes.function suites/test_suite_aes.rest.data scripts/generate_code.pl suites/helpers.function suites/main_test.function
 	echo "  Gen   $@"
 	perl scripts/generate_code.pl suites test_suite_aes test_suite_aes.rest
@@ -214,6 +219,10 @@
 	echo "  CC    $<"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) $<	$(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
 
+test_suite_aes.ofb$(EXEXT): test_suite_aes.ofb.c $(DEP)
+	echo "  CC    $<"
+	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) $<	$(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
+
 test_suite_aes.rest$(EXEXT): test_suite_aes.rest.c $(DEP)
 	echo "  CC    $<"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) $<	$(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
diff --git a/tests/suites/test_suite_aes.function b/tests/suites/test_suite_aes.function
index c5f0eaa..c45a9ed 100644
--- a/tests/suites/test_suite_aes.function
+++ b/tests/suites/test_suite_aes.function
@@ -289,6 +289,58 @@
 }
 /* END_CASE */
 
+/* BEGIN_CASE depends_on:MBEDTLS_CIPHER_MODE_OFB */
+void aes_encrypt_ofb( int fragment_size, char *hex_key_string,
+                        char *hex_iv_string, char *hex_src_string,
+                        char *hex_dst_string )
+{
+    unsigned char key_str[100];
+    unsigned char iv_str[100];
+    unsigned char src_str[200];
+    unsigned char dst_str[200];
+    unsigned char output[200];
+    mbedtls_aes_context ctx;
+    size_t iv_offset = 0;
+    int in_buffer_len;
+    unsigned char* src_str_next;
+    int key_len;
+
+    memset(key_str, 0x00, 100);
+    memset(iv_str, 0x00, 100);
+    memset(src_str, 0x00, 200);
+    memset(dst_str, 0x00, 200);
+    memset(output, 0x00, 200);
+    mbedtls_aes_init( &ctx );
+
+    key_len = unhexify( key_str, hex_key_string );
+    unhexify( iv_str, hex_iv_string );
+    in_buffer_len = unhexify( src_str, hex_src_string );
+
+    TEST_ASSERT( mbedtls_aes_setkey_enc( &ctx, key_str, key_len * 8 ) == 0 );
+    src_str_next = src_str;
+
+    while( in_buffer_len > 0 )
+    {
+        TEST_ASSERT( mbedtls_aes_crypt_ofb( &ctx, fragment_size, &iv_offset,
+                                            iv_str, src_str_next, output ) == 0 );
+
+        hexify( dst_str, output, fragment_size );
+        TEST_ASSERT( strncmp( (char *) dst_str, hex_dst_string,
+                                ( 2 * fragment_size) ) == 0 );
+
+        in_buffer_len -= fragment_size;
+        hex_dst_string += ( fragment_size * 2 );
+        src_str_next += fragment_size;
+
+        if( in_buffer_len < fragment_size )
+            fragment_size = in_buffer_len;
+    }
+
+exit:
+    mbedtls_aes_free( &ctx );
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_SELF_TEST */
 void aes_selftest()
 {
diff --git a/tests/suites/test_suite_aes.ofb.data b/tests/suites/test_suite_aes.ofb.data
new file mode 100644
index 0000000..4b9d80e
--- /dev/null
+++ b/tests/suites/test_suite_aes.ofb.data
@@ -0,0 +1,35 @@
+# NIST Special Publication 800-38A
+# Recommendation for Block Cipher Modes of Operation
+# Test Vectors - Appendix F, Section F.4
+OFB-AES128.Encrypt - Single block
+depends_on:MBEDTLS_CIPHER_MODE_OFB
+aes_encrypt_ofb:16:"2b7e151628aed2a6abf7158809cf4f3c":"000102030405060708090a0b0c0d0e0f":"6bc1bee22e409f96e93d7e117393172a":"3b3fd92eb72dad20333449f8e83cfb4a"
+
+OFB-AES128.Encrypt - Partial blocks - 7 bytes
+depends_on:MBEDTLS_CIPHER_MODE_OFB
+aes_encrypt_ofb:5:"2b7e151628aed2a6abf7158809cf4f3c":"000102030405060708090a0b0c0d0e0f":"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710":"3b3fd92eb72dad20333449f8e83cfb4a7789508d16918f03f53c52dac54ed8259740051e9c5fecf64344f7a82260edcc304c6528f659c77866a510d9c1d6ae5e"
+
+OFB-AES128.Encrypt - Test NIST SP800-38A - F.4.1
+depends_on:MBEDTLS_CIPHER_MODE_OFB
+aes_encrypt_ofb:16:"2b7e151628aed2a6abf7158809cf4f3c":"000102030405060708090a0b0c0d0e0f":"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710":"3b3fd92eb72dad20333449f8e83cfb4a7789508d16918f03f53c52dac54ed8259740051e9c5fecf64344f7a82260edcc304c6528f659c77866a510d9c1d6ae5e"
+
+OFB-AES128.Decrypt - Test NIST SP800-38A - F.4.2
+depends_on:MBEDTLS_CIPHER_MODE_OFB
+aes_encrypt_ofb:16:"2b7e151628aed2a6abf7158809cf4f3c":"000102030405060708090a0b0c0d0e0f":"3b3fd92eb72dad20333449f8e83cfb4a7789508d16918f03f53c52dac54ed8259740051e9c5fecf64344f7a82260edcc304c6528f659c77866a510d9c1d6ae5e":"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710"
+
+OFB-AES192.Encrypt - Test NIST SP800-38A - F.4.3
+depends_on:MBEDTLS_CIPHER_MODE_OFB
+aes_encrypt_ofb:16:"8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b":"000102030405060708090a0b0c0d0e0f":"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710":"cdc80d6fddf18cab34c25909c99a4174fcc28b8d4c63837c09e81700c11004018d9a9aeac0f6596f559c6d4daf59a5f26d9f200857ca6c3e9cac524bd9acc92a"
+
+OFB-AES192.Decrypt - Test NIST SP800-38A - F.4.4
+depends_on:MBEDTLS_CIPHER_MODE_OFB
+aes_encrypt_ofb:16:"8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b":"000102030405060708090a0b0c0d0e0f":"cdc80d6fddf18cab34c25909c99a4174fcc28b8d4c63837c09e81700c11004018d9a9aeac0f6596f559c6d4daf59a5f26d9f200857ca6c3e9cac524bd9acc92a":"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710"
+
+OFB-AES256.Encrypt - Test NIST SP800-38A - F.4.5
+depends_on:MBEDTLS_CIPHER_MODE_OFB
+aes_encrypt_ofb:16:"603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4":"000102030405060708090a0b0c0d0e0f":"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710":"dc7e84bfda79164b7ecd8486985d38604febdc6740d20b3ac88f6ad82a4fb08d71ab47a086e86eedf39d1c5bba97c4080126141d67f37be8538f5a8be740e484"
+
+OFB-AES256.Decrypt - Test NIST SP800-38A - F.4.6
+depends_on:MBEDTLS_CIPHER_MODE_OFB
+aes_encrypt_ofb:16:"603deb1015ca71be2b73aef0857d77811f352c073b6108d72d9810a30914dff4":"000102030405060708090a0b0c0d0e0f":"dc7e84bfda79164b7ecd8486985d38604febdc6740d20b3ac88f6ad82a4fb08d71ab47a086e86eedf39d1c5bba97c4080126141d67f37be8538f5a8be740e484":"6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710"
+
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