Key wrapping API definition

Define the Key Wrapping API

include/mbedtls/check_config.h

@@ -87,6 +87,11 @@
 #error "MBEDTLS_CMAC_C defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_NIST_KW_C) && \
+    ( !defined(MBEDTLS_AES_C) || !defined(MBEDTLS_CIPHER_C) )
+#error "MBEDTLS_NIST_KW_C defined, but not all prerequisites"
+#endif
+
 #if defined(MBEDTLS_ECDH_C) && !defined(MBEDTLS_ECP_C)
 #error "MBEDTLS_ECDH_C defined, but not all prerequisites"
 #endif

include/mbedtls/config.h

@@ -308,6 +308,7 @@
 //#define MBEDTLS_DHM_ALT
 //#define MBEDTLS_ECJPAKE_ALT
 //#define MBEDTLS_GCM_ALT
+//#define MBEDTLS_NIST_KW_ALT
 //#define MBEDTLS_MD2_ALT
 //#define MBEDTLS_MD4_ALT
 //#define MBEDTLS_MD5_ALT
@@ -2248,6 +2249,19 @@
  */
 #define MBEDTLS_HMAC_DRBG_C
 
+/**
+ * \def MBEDTLS_NIST_KW_C
+ *
+ * Enable the Key Wrapping mode for 128-bit block ciphers,
+ * as defined in NIST SP 800-38F. Only KW and KWP modes
+ * are supported. At the moment, only AES is approved by NIST.
+ *
+ * Module:  library/nist_kw.c
+ *
+ * Requires: MBEDTLS_AES_C and MBEDTLS_CIPHER_C
+ */
+//#define MBEDTLS_NIST_KW_C
+
 /**
  * \def MBEDTLS_MD_C
  *

include/mbedtls/nist_kw.h

@@ -0,0 +1,178 @@
+/**
+ * \file nist_kw.h
+ *
+ * \brief This file provides an API for key wrapping (KW) and key wrapping with
+ *        padding (KWP) as defined in NIST SP 800-38F.
+ *        https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-38F.pdf
+ *
+ *        Key wrapping specifies a deterministic authenticated-encryption mode
+ *        of operation, according to <em>NIST SP 800-38F: Recommendation for
+ *        Block Cipher Modes of Operation: Methods for Key Wrapping</em>. Its
+ *        purpose is to protect cryptographic keys.
+ *
+ *        Its equivalent is RFC 3394 for KW, and RFC 5649 for KWP.
+ *        https://tools.ietf.org/html/rfc3394
+ *        https://tools.ietf.org/html/rfc5649
+ *
+ */
+/*
+ *  Copyright (C) 2018, Arm Limited (or its affiliates), All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of Mbed TLS (https://tls.mbed.org)
+ */
+
+#ifndef MBEDTLS_NIST_KW_H
+#define MBEDTLS_NIST_KW_H
+
+#include "cipher.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum
+{
+    MBEDTLS_KW_MODE_KW = 0,
+    MBEDTLS_KW_MODE_KWP = 1
+} mbedtls_nist_kw_mode_t;
+
+#if !defined(MBEDTLS_NIST_KW_ALT)
+// Regular implementation
+//
+
+/**
+ * \brief    The key wrapping context-type definition. The key wrapping context is passed
+ *           to the APIs called.
+ *
+ * \note     The definition of this type may change in future library versions.
+ *           Don't make any assumptions on this context!
+ */
+typedef struct {
+    mbedtls_cipher_context_t cipher_ctx;    /*!< The cipher context used. */
+} mbedtls_nist_kw_context;
+
+#else  /* MBEDTLS_NIST_key wrapping_ALT */
+#include "nist_kw_alt.h"
+#endif /* MBEDTLS_NIST_KW_ALT */
+
+/**
+ * \brief           This function initializes the specified key wrapping context
+ *                  to make references valid and prepare the context
+ *                  for mbedtls_nist_kw_setkey() or mbedtls_nist_kw_free().
+ *
+ * \param ctx       The key wrapping context to initialize.
+ *
+ */
+void mbedtls_nist_kw_init( mbedtls_nist_kw_context *ctx );
+
+/**
+ * \brief           This function initializes the key wrapping context set in the
+ *                  \p ctx parameter and sets the encryption key.
+ *
+ * \param ctx       The key wrapping context.
+ * \param cipher    The 128-bit block cipher to use. Only AES is supported.
+ * \param key       The Key Encryption Key (KEK).
+ * \param keybits   The KEK size in bits. This must be acceptable by the cipher.
+ * \param is_wrap   Specify whether the operation within the context is wrapping or unwrapping
+ *
+ * \return          \c 0 on success.
+ * \return          \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for any invalid input.
+ * \return          \c MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE for 128-bit block ciphers
+ *                  which are not supported.
+ * \return          cipher-specific error code on failure of the underlying cipher.
+ */
+int mbedtls_nist_kw_setkey( mbedtls_nist_kw_context *ctx,
+                            mbedtls_cipher_id_t cipher,
+                            const unsigned char *key,
+                            unsigned int keybits,
+                            const int is_wrap );
+
+/**
+ * \brief   This function releases and clears the specified key wrapping context
+ *          and underlying cipher sub-context.
+ *
+ * \param ctx       The key wrapping context to clear.
+ */
+void mbedtls_nist_kw_free( mbedtls_nist_kw_context *ctx );
+
+/**
+ * \brief           This function encrypts a buffer using key wrapping.
+ *
+ * \param ctx       The key wrapping context to use for encryption.
+ * \param mode      The key wrapping mode to use (MBEDTLS_KW_MODE_KW or MBEDTLS_KW_MODE_KWP)
+ * \param input     The buffer holding the input data.
+ * \param in_len    The length of the input data in Bytes.
+ *                  The input uses units of 8 Bytes called semiblocks.
+ *                  <ul><li>For KW mode: a multiple of 8 bytes between 16 and 2^57-8 inclusive. </li>
+ *                  <li>For KWP mode: any length between 1 and 2^32-1 inclusive.</li></ul>
+ * \param[out] output    The buffer holding the output data.
+ *                  <ul><li>For KW mode: Must be at least 8 bytes larger than \p in_len.</li>
+ *                  <li>For KWP mode: Must be at least 8 bytes larger rounded up to a multiple of
+ *                  8 bytes for KWP (15 bytes at most).</li></ul>
+ * \param[out] out_len The number of bytes written to the output buffer. \c 0 on failure.
+ * \param[in] out_size The capacity of the output buffer.
+ *
+ * \return          \c 0 on success.
+ * \return          \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length.
+ * \return          cipher-specific error code on failure of the underlying cipher.
+ */
+int mbedtls_nist_kw_wrap( mbedtls_nist_kw_context *ctx, mbedtls_nist_kw_mode_t mode,
+                          const unsigned char *input, size_t in_len,
+                          unsigned char *output, size_t* out_len, size_t out_size );
+
+/**
+ * \brief           This function decrypts a buffer using key wrapping.
+ *
+ * \param ctx       The key wrapping context to use for decryption.
+ * \param mode      The key wrapping mode to use (MBEDTLS_KW_MODE_KW or MBEDTLS_KW_MODE_KWP)
+ * \param input     The buffer holding the input data.
+ * \param in_len    The length of the input data in Bytes.
+ *                  The input uses units of 8 Bytes called semiblocks.
+ *                  The input must be a multiple of semiblocks.
+ *                  <ul><li>For KW mode: a multiple of 8 bytes between 24 and 2^57 inclusive. </li>
+ *                  <li>For KWP mode: a multiple of 8 bytes between 16 and 2^32 inclusive.</li></ul>
+ * \param[out] output    The buffer holding the output data.
+ *                  The output buffer's minimal length is 8 bytes shorter than \p in_len.
+ * \param[out] out_len The number of bytes written to the output buffer. \c 0 on failure.
+ *                  For KWP mode, the length could be up to 15 bytes shorter than \p in_len,
+ *                  depending on how much padding was added to the data.
+ * \param[in] out_size The capacity of the output buffer.
+ *
+ * \return          \c 0 on success.
+ * \return          \c MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA for invalid input length.
+ * \return          \c MBEDTLS_ERR_CIPHER_AUTH_FAILED for verification failure of the ciphertext.
+ * \return          cipher-specific error code on failure of the underlying cipher.
+ */
+int mbedtls_nist_kw_unwrap( mbedtls_nist_kw_context *ctx, mbedtls_nist_kw_mode_t mode,
+                            const unsigned char *input, size_t in_len,
+                            unsigned char *output, size_t* out_len, size_t out_size);
+
+
+#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
+/**
+ * \brief          The key wrapping checkup routine.
+ *
+ * \return         \c 0 on success.
+ * \return         \c 1 on failure.
+ */
+int mbedtls_nist_kw_self_test( int verbose );
+#endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MBEDTLS_NIST_KW_H */

library/version_features.c

@@ -126,6 +126,9 @@ static const char *features[] = {
 #if defined(MBEDTLS_GCM_ALT)
     "MBEDTLS_GCM_ALT",
 #endif /* MBEDTLS_GCM_ALT */
+#if defined(MBEDTLS_NIST_KW_ALT)
+    "MBEDTLS_NIST_KW_ALT",
+#endif /* MBEDTLS_NIST_KW_ALT */
 #if defined(MBEDTLS_MD2_ALT)
     "MBEDTLS_MD2_ALT",
 #endif /* MBEDTLS_MD2_ALT */
@@ -618,6 +621,9 @@ static const char *features[] = {
 #if defined(MBEDTLS_HMAC_DRBG_C)
     "MBEDTLS_HMAC_DRBG_C",
 #endif /* MBEDTLS_HMAC_DRBG_C */
+#if defined(MBEDTLS_NIST_KW_C)
+    "MBEDTLS_NIST_KW_C",
+#endif /* MBEDTLS_NIST_KW_C */
 #if defined(MBEDTLS_MD_C)
     "MBEDTLS_MD_C",
 #endif /* MBEDTLS_MD_C */