[398] | 1 | /**
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| 2 | * \file hkdf.h
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| 3 | *
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| 4 | * \brief This file contains the HKDF interface.
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| 5 | *
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| 6 | * The HMAC-based Extract-and-Expand Key Derivation Function (HKDF) is
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| 7 | * specified by RFC 5869.
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| 8 | */
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| 9 | /*
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| 10 | * Copyright (C) 2016-2018, ARM Limited, All Rights Reserved
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| 11 | * SPDX-License-Identifier: Apache-2.0
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| 12 | *
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| 13 | * Licensed under the Apache License, Version 2.0 (the "License"); you may
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| 14 | * not use this file except in compliance with the License.
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| 15 | * You may obtain a copy of the License at
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| 16 | *
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| 17 | * http://www.apache.org/licenses/LICENSE-2.0
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| 18 | *
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| 19 | * Unless required by applicable law or agreed to in writing, software
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| 20 | * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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| 21 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 22 | * See the License for the specific language governing permissions and
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| 23 | * limitations under the License.
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| 24 | *
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| 25 | * This file is part of mbed TLS (https://tls.mbed.org)
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| 26 | */
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| 27 | #ifndef MBEDTLS_HKDF_H
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| 28 | #define MBEDTLS_HKDF_H
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| 29 |
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| 30 | #if !defined(MBEDTLS_CONFIG_FILE)
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| 31 | #include "config.h"
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| 32 | #else
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| 33 | #include MBEDTLS_CONFIG_FILE
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| 34 | #endif
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| 35 |
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| 36 | #include "md.h"
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| 37 |
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| 38 | /**
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| 39 | * \name HKDF Error codes
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| 40 | * \{
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| 41 | */
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| 42 | #define MBEDTLS_ERR_HKDF_BAD_INPUT_DATA -0x5F80 /**< Bad input parameters to function. */
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| 43 | /* \} name */
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| 44 |
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| 45 | #ifdef __cplusplus
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| 46 | extern "C" {
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| 47 | #endif
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| 48 |
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| 49 | /**
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| 50 | * \brief This is the HMAC-based Extract-and-Expand Key Derivation Function
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| 51 | * (HKDF).
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| 52 | *
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| 53 | * \param md A hash function; md.size denotes the length of the hash
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| 54 | * function output in bytes.
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| 55 | * \param salt An optional salt value (a non-secret random value);
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| 56 | * if the salt is not provided, a string of all zeros of
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| 57 | * md.size length is used as the salt.
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| 58 | * \param salt_len The length in bytes of the optional \p salt.
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| 59 | * \param ikm The input keying material.
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| 60 | * \param ikm_len The length in bytes of \p ikm.
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| 61 | * \param info An optional context and application specific information
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| 62 | * string. This can be a zero-length string.
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| 63 | * \param info_len The length of \p info in bytes.
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| 64 | * \param okm The output keying material of \p okm_len bytes.
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| 65 | * \param okm_len The length of the output keying material in bytes. This
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| 66 | * must be less than or equal to 255 * md.size bytes.
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| 67 | *
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| 68 | * \return 0 on success.
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| 69 | * \return #MBEDTLS_ERR_HKDF_BAD_INPUT_DATA when the parameters are invalid.
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| 70 | * \return An MBEDTLS_ERR_MD_* error for errors returned from the underlying
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| 71 | * MD layer.
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| 72 | */
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| 73 | int mbedtls_hkdf( const mbedtls_md_info_t *md, const unsigned char *salt,
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| 74 | size_t salt_len, const unsigned char *ikm, size_t ikm_len,
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| 75 | const unsigned char *info, size_t info_len,
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| 76 | unsigned char *okm, size_t okm_len );
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| 77 |
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| 78 | /**
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| 79 | * \brief Take the input keying material \p ikm and extract from it a
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| 80 | * fixed-length pseudorandom key \p prk.
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| 81 | *
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| 82 | * \warning This function should only be used if the security of it has been
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| 83 | * studied and established in that particular context (eg. TLS 1.3
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| 84 | * key schedule). For standard HKDF security guarantees use
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| 85 | * \c mbedtls_hkdf instead.
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| 86 | *
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| 87 | * \param md A hash function; md.size denotes the length of the
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| 88 | * hash function output in bytes.
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| 89 | * \param salt An optional salt value (a non-secret random value);
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| 90 | * if the salt is not provided, a string of all zeros
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| 91 | * of md.size length is used as the salt.
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| 92 | * \param salt_len The length in bytes of the optional \p salt.
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| 93 | * \param ikm The input keying material.
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| 94 | * \param ikm_len The length in bytes of \p ikm.
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| 95 | * \param[out] prk A pseudorandom key of at least md.size bytes.
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| 96 | *
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| 97 | * \return 0 on success.
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| 98 | * \return #MBEDTLS_ERR_HKDF_BAD_INPUT_DATA when the parameters are invalid.
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| 99 | * \return An MBEDTLS_ERR_MD_* error for errors returned from the underlying
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| 100 | * MD layer.
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| 101 | */
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| 102 | int mbedtls_hkdf_extract( const mbedtls_md_info_t *md,
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| 103 | const unsigned char *salt, size_t salt_len,
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| 104 | const unsigned char *ikm, size_t ikm_len,
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| 105 | unsigned char *prk );
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| 106 |
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| 107 | /**
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| 108 | * \brief Expand the supplied \p prk into several additional pseudorandom
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| 109 | * keys, which is the output of the HKDF.
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| 110 | *
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| 111 | * \warning This function should only be used if the security of it has been
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| 112 | * studied and established in that particular context (eg. TLS 1.3
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| 113 | * key schedule). For standard HKDF security guarantees use
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| 114 | * \c mbedtls_hkdf instead.
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| 115 | *
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| 116 | * \param md A hash function; md.size denotes the length of the hash
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| 117 | * function output in bytes.
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| 118 | * \param prk A pseudorandom key of at least md.size bytes. \p prk is
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| 119 | * usually the output from the HKDF extract step.
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| 120 | * \param prk_len The length in bytes of \p prk.
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| 121 | * \param info An optional context and application specific information
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| 122 | * string. This can be a zero-length string.
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| 123 | * \param info_len The length of \p info in bytes.
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| 124 | * \param okm The output keying material of \p okm_len bytes.
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| 125 | * \param okm_len The length of the output keying material in bytes. This
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| 126 | * must be less than or equal to 255 * md.size bytes.
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| 127 | *
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| 128 | * \return 0 on success.
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| 129 | * \return #MBEDTLS_ERR_HKDF_BAD_INPUT_DATA when the parameters are invalid.
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| 130 | * \return An MBEDTLS_ERR_MD_* error for errors returned from the underlying
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| 131 | * MD layer.
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| 132 | */
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| 133 | int mbedtls_hkdf_expand( const mbedtls_md_info_t *md, const unsigned char *prk,
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| 134 | size_t prk_len, const unsigned char *info,
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| 135 | size_t info_len, unsigned char *okm, size_t okm_len );
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| 136 |
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| 137 | #ifdef __cplusplus
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| 138 | }
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| 139 | #endif
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| 140 |
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| 141 | #endif /* hkdf.h */
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