Add an HKDF (RFC 5869) implementation
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index be80332..4689f3a 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -4,7 +4,7 @@
* \brief Consistency checks for configuration options
*/
/*
- * Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
+ * Copyright (C) 2006-2018, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -191,6 +191,10 @@
#error "MBEDTLS_HAVEGE_C defined, but not all prerequisites"
#endif
+#if defined(MBEDTLS_HKDF_C) && !defined(MBEDTLS_MD_C)
+#error "MBEDTLS_HKDF_C defined, but not all prerequisites"
+#endif
+
#if defined(MBEDTLS_HMAC_DRBG_C) && !defined(MBEDTLS_MD_C)
#error "MBEDTLS_HMAC_DRBG_C defined, but not all prerequisites"
#endif
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 7c9acb2..a59e9c5 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -8,7 +8,7 @@
* memory footprint.
*/
/*
- * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ * Copyright (C) 2006-2018, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -2092,6 +2092,21 @@
//#define MBEDTLS_HAVEGE_C
/**
+ * \def MBEDTLS_HKDF_C
+ *
+ * Enable the HKDF algorithm (RFC 5869).
+ *
+ * Module: library/hkdf.c
+ * Caller:
+ *
+ * Requires: MBEDTLS_MD_C
+ *
+ * This module adds support for the Hashed Message Authentication Code
+ * (HMAC)-based key derivation function (HKDF).
+ */
+#define MBEDTLS_HKDF_C
+
+/**
* \def MBEDTLS_HMAC_DRBG_C
*
* Enable the HMAC_DRBG random generator.
diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 8b4d3a8..c7f6a72 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -4,7 +4,7 @@
* \brief Error to string translation
*/
/*
- * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ * Copyright (C) 2006-2018, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
@@ -88,6 +88,7 @@
* RSA 4 11
* ECP 4 9 (Started from top)
* MD 5 5
+ * HKDF 5 1 (Started from top)
* CIPHER 6 8
* SSL 6 17 (Started from top)
* SSL 7 31
diff --git a/include/mbedtls/hkdf.h b/include/mbedtls/hkdf.h
new file mode 100644
index 0000000..6833e72
--- /dev/null
+++ b/include/mbedtls/hkdf.h
@@ -0,0 +1,125 @@
+/**
+ * \file hkdf.h
+ *
+ * \brief This file contains the HKDF interface.
+ *
+ * The HMAC-based Extract-and-Expand Key Derivation Function (HKDF) is
+ * specified by RFC 5869.
+ */
+/*
+ * Copyright (C) 2016-2018, ARM Limited, 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_HKDF_H
+#define MBEDTLS_HKDF_H
+
+#include "md.h"
+
+/**
+ * \name HKDF Error codes
+ * \{
+ */
+#define MBEDTLS_ERR_HKDF_BAD_INPUT_DATA -0x5F80 /**< Bad input parameters to function. */
+/* \} name */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief This is the HMAC-based Extract-and-Expand Key Derivation Function
+ * (HKDF).
+ *
+ * \param md A hash function; md.size denotes the length of the hash
+ * function output in bytes.
+ * \param salt An optional salt value (a non-secret random value);
+ * if the salt is not provided, a string of all zeros of
+ * md.size length is used as the salt.
+ * \param salt_len The length in bytes of the optional \p salt.
+ * \param ikm The input keying material.
+ * \param ikm_len The length in bytes of \p ikm.
+ * \param info An optional context and application specific information
+ * string. This can be a zero-length string.
+ * \param info_len The length of \p info in bytes.
+ * \param okm The output keying material of \p okm_len bytes.
+ * \param okm_len The length of the output keying material in bytes. This
+ * must be less than or equal to 255 * md.size bytes.
+ *
+ * \return 0 on success.
+ * \return #MBEDTLS_ERR_HKDF_BAD_INPUT_DATA when the parameters are invalid.
+ * \return An MBEDTLS_ERR_MD_* error for errors returned from the underlying
+ * MD layer.
+ */
+int mbedtls_hkdf( const mbedtls_md_info_t *md, const unsigned char *salt,
+ size_t salt_len, const unsigned char *ikm, size_t ikm_len,
+ const unsigned char *info, size_t info_len,
+ unsigned char *okm, size_t okm_len );
+
+/**
+ * \brief Take the input keying material \p ikm and extract from it a
+ * fixed-length pseudorandom key \p prk.
+ *
+ * \param md A hash function; md.size denotes the length of the
+ * hash function output in bytes.
+ * \param salt An optional salt value (a non-secret random value);
+ * if the salt is not provided, a string of all zeros
+ * of md.size length is used as the salt.
+ * \param salt_len The length in bytes of the optional \p salt.
+ * \param ikm The input keying material.
+ * \param ikm_len The length in bytes of \p ikm.
+ * \param[out] prk A pseudorandom key of at least md.size bytes.
+ *
+ * \return 0 on success.
+ * \return #MBEDTLS_ERR_HKDF_BAD_INPUT_DATA when the parameters are invalid.
+ * \return An MBEDTLS_ERR_MD_* error for errors returned from the underlying
+ * MD layer.
+ */
+int mbedtls_hkdf_extract( const mbedtls_md_info_t *md,
+ const unsigned char *salt, size_t salt_len,
+ const unsigned char *ikm, size_t ikm_len,
+ unsigned char *prk );
+
+/**
+ * \brief Expand the supplied \p prk into several additional pseudorandom
+ * keys, which is the output of the HKDF.
+ *
+ * \param md A hash function; md.size denotes the length of the hash
+ * function output in bytes.
+ * \param prk A pseudorandom key of at least md.size bytes. \p prk is usually,
+ * the output from the HKDF extract step.
+ * \param prk_len The length in bytes of \p prk.
+ * \param info An optional context and application specific information
+ * string. This can be a zero-length string.
+ * \param info_len The length of \p info in bytes.
+ * \param okm The output keying material of \p okm_len bytes.
+ * \param okm_len The length of the output keying material in bytes. This
+ * must be less than or equal to 255 * md.size bytes.
+ *
+ * \return 0 on success.
+ * \return #MBEDTLS_ERR_HKDF_BAD_INPUT_DATA when the parameters are invalid.
+ * \return An MBEDTLS_ERR_MD_* error for errors returned from the underlying
+ * MD layer.
+ */
+int mbedtls_hkdf_expand( const mbedtls_md_info_t *md, const unsigned char *prk,
+ size_t prk_len, const unsigned char *info,
+ size_t info_len, unsigned char *okm, size_t okm_len );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* hkdf.h */