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hkdf.c Go to the documentation of this file.
1 /** 2 * @file hkdf.c 3 * @brief HKDF (HMAC-based Key Derivation Function) 4 * 5 * @section License 6 * 7 * SPDX-License-Identifier: GPL-2.0-or-later 8 * 9 * Copyright (C) 2010-2026 Oryx Embedded SARL. All rights reserved. 10 * 11 * This file is part of CycloneCRYPTO Open. 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License 15 * as published by the Free Software Foundation; either version 2 16 * of the License, or (at your option) any later version. 17 * 18 * This program is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 21 * GNU General Public License for more details. 22 * 23 * You should have received a copy of the GNU General Public License 24 * along with this program; if not, write to the Free Software Foundation, 25 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. 26 * 27 * @section Description 28 * 29 * HKDF is a simple HMAC-based key derivation function which can be used as a 30 * building block in various protocols and applications. Refer to RFC 5869 for 31 * more details 32 * 33 * @author Oryx Embedded SARL (www.oryx-embedded.com) 34 * @version 2.6.0 35 **/ 36 37 //Switch to the appropriate trace level 38 #define TRACE_LEVEL CRYPTO_TRACE_LEVEL 39 40 //Dependencies 41 #include "core/crypto.h" 42 #include "kdf/hkdf.h" 43 #include "mac/hmac.h" 44 45 //Check crypto library configuration 46 #if (HKDF_SUPPORT == ENABLED) 47 48 49 /** 50 * @brief HKDF key derivation function 51 * @param[in] hash Underlying hash function 52 * @param[in] ikm input keying material 53 * @param[in] ikmLen Length in the input keying material 54 * @param[in] salt Optional salt value (a non-secret random value) 55 * @param[in] saltLen Length of the salt 56 * @param[in] info Optional application specific information 57 * @param[in] infoLen Length of the application specific information 58 * @param[out] okm output keying material 59 * @param[in] okmLen Length of the output keying material 60 * @return Error code 61 **/ 62 63 error_t hkdf(
const HashAlgo *hash,
const uint8_t *ikm,
size_t ikmLen,
64 const uint8_t *salt,
size_t saltLen,
const uint8_t *info,
size_t infoLen,
65 uint8_t *okm,
size_t okmLen)
66 {
67 error_t error;
68 uint8_t prk[MAX_HASH_DIGEST_SIZE];
69 70 //Perform HKDF extract step 71 error = hkdfExtract(hash, ikm, ikmLen, salt, saltLen, prk);
72 73 //Check status code 74 if(!error)
75 {
76 //Perform HKDF expand step 77 error = hkdfExpand(hash, prk, hash->digestSize, info, infoLen,
78 okm, okmLen);
79 }
80 81 //Return status code 82 return error;
83 }
84 85 86 /** 87 * @brief HKDF extract step 88 * @param[in] hash Underlying hash function 89 * @param[in] ikm input keying material 90 * @param[in] ikmLen Length in the input keying material 91 * @param[in] salt Optional salt value (a non-secret random value) 92 * @param[in] saltLen Length of the salt 93 * @param[out] prk Pseudorandom key 94 * @return Error code 95 **/ 96 97 error_t hkdfExtract(
const HashAlgo *hash,
const uint8_t *ikm,
size_t ikmLen,
98 const uint8_t *salt,
size_t saltLen, uint8_t *prk)
99 {
100 #if (CRYPTO_STATIC_MEM_SUPPORT == DISABLED) 101 HmacContext *hmacContext;
102 #else 103 HmacContext hmacContext[1];
104 #endif 105 106 //Check parameters 107 if(hash == NULL || ikm == NULL || prk == NULL)
108 return ERROR_INVALID_PARAMETER;
109 110 //The salt parameter is optional 111 if(salt == NULL && saltLen != 0)
112 return ERROR_INVALID_PARAMETER;
113 114 #if (CRYPTO_STATIC_MEM_SUPPORT == DISABLED) 115 //Allocate a memory buffer to hold the HMAC context 116 hmacContext = cryptoAllocMem(
sizeof(HmacContext));
117 //Failed to allocate memory? 118 if(hmacContext == NULL)
119 return ERROR_OUT_OF_MEMORY;
120 #endif 121 122 //The salt parameter is optional 123 if(salt == NULL)
124 {
125 //If the salt is not provided, it is set to a string of HashLen zeros 126 osMemset(hmacContext->digest, 0, hash->digestSize);
127 salt = hmacContext->digest;
128 saltLen = hash->digestSize;
129 }
130 131 //Compute PRK = HMAC-Hash(salt, IKM) 132 hmacInit(hmacContext, hash, salt, saltLen);
133 hmacUpdate(hmacContext, ikm, ikmLen);
134 hmacFinal(hmacContext, prk);
135 136 #if (CRYPTO_STATIC_MEM_SUPPORT == DISABLED) 137 //Free previously allocated memory 138 cryptoFreeMem(hmacContext);
139 #endif 140 141 //Successful processing 142 return NO_ERROR;
143 }
144 145 146 /** 147 * @brief HKDF expand step 148 * @param[in] hash Underlying hash function 149 * @param[in] prk Pseudorandom key 150 * @param[in] prkLen Length of the pseudorandom key 151 * @param[in] info Optional application specific information 152 * @param[in] infoLen Length of the application specific information 153 * @param[out] okm output keying material 154 * @param[in] okmLen Length of the output keying material 155 * @return Error code 156 **/ 157 158 error_t hkdfExpand(
const HashAlgo *hash,
const uint8_t *prk,
size_t prkLen,
159 const uint8_t *info,
size_t infoLen, uint8_t *okm,
size_t okmLen)
160 {
161 uint8_t i;
162 size_t tLen;
163 uint8_t t[MAX_HASH_DIGEST_SIZE];
164 #if (CRYPTO_STATIC_MEM_SUPPORT == DISABLED) 165 HmacContext *hmacContext;
166 #else 167 HmacContext hmacContext[1];
168 #endif 169 170 //Check parameters 171 if(hash == NULL || prk == NULL || okm == NULL)
172 return ERROR_INVALID_PARAMETER;
173 174 //The application specific information parameter is optional 175 if(info == NULL && infoLen != 0)
176 return ERROR_INVALID_PARAMETER;
177 178 //PRK must be at least HashLen octets 179 if(prkLen < hash->digestSize)
180 return ERROR_INVALID_LENGTH;
181 182 //Check the length of the output keying material 183 if(okmLen > (255 * hash->digestSize))
184 return ERROR_INVALID_LENGTH;
185 186 #if (CRYPTO_STATIC_MEM_SUPPORT == DISABLED) 187 //Allocate a memory buffer to hold the HMAC context 188 hmacContext = cryptoAllocMem(
sizeof(HmacContext));
189 //Failed to allocate memory? 190 if(hmacContext == NULL)
191 return ERROR_OUT_OF_MEMORY;
192 #endif 193 194 //T(0) is an empty string (zero length) 195 tLen = 0;
196 197 //Iterate as many times as required 198 for(i = 1; okmLen > 0; i++)
199 {
200 //Compute T(i) = HMAC-Hash(PRK, T(i-1) | info | i) 201 hmacInit(hmacContext, hash, prk, prkLen);
202 hmacUpdate(hmacContext, t, tLen);
203 hmacUpdate(hmacContext, info, infoLen);
204 hmacUpdate(hmacContext, &i,
sizeof(i));
205 hmacFinal(hmacContext, t);
206 207 //Number of octets in the current block 208 tLen = MIN(okmLen, hash->digestSize);
209 //Save the resulting block 210 osMemcpy(okm, t, tLen);
211 212 //Point to the next block 213 okm += tLen;
214 okmLen -= tLen;
215 }
216 217 #if (CRYPTO_STATIC_MEM_SUPPORT == DISABLED) 218 //Free previously allocated memory 219 cryptoFreeMem(hmacContext);
220 #endif 221 222 //Successful processing 223 return NO_ERROR;
224 }
225 226 #endif HmacContextHMAC algorithm context.Definition: hmac.h:59 tuint8_t tDefinition: lldp_ext_med.h:212 HashAlgo::digestSizesize_t digestSizeDefinition: crypto.h:1157 ERROR_OUT_OF_MEMORY@ ERROR_OUT_OF_MEMORYDefinition: error.h:63 MAX_HASH_DIGEST_SIZE#define MAX_HASH_DIGEST_SIZEDefinition: hash_algorithms.h:238 ERROR_INVALID_PARAMETER@ ERROR_INVALID_PARAMETERInvalid parameter.Definition: error.h:47 osMemcpy#define osMemcpy(dest, src, length)Definition: os_port.h:144 error_terror_tError codes.Definition: error.h:43 ERROR_INVALID_LENGTH@ ERROR_INVALID_LENGTHDefinition: error.h:111 crypto.hGeneral definitions for cryptographic algorithms. hkdfExpanderror_t hkdfExpand(const HashAlgo *hash, const uint8_t *prk, size_t prkLen, const uint8_t *info, size_t infoLen, uint8_t *okm, size_t okmLen)HKDF expand step.Definition: hkdf.c:158 MIN#define MIN(a, b)Definition: os_port.h:63 hmacUpdate__weak_func void hmacUpdate(HmacContext *context, const void *data, size_t length)Update the HMAC context with a portion of the message being hashed.Definition: hmac.c:201 HmacContext::digestuint8_t digest[MAX_HASH_DIGEST_SIZE]Definition: hmac.h:63 hkdf.hHKDF (HMAC-based Key Derivation Function) hmacFinal__weak_func void hmacFinal(HmacContext *context, uint8_t *digest)Finish the HMAC calculation.Definition: hmac.c:218 hkdferror_t hkdf(const HashAlgo *hash, const uint8_t *ikm, size_t ikmLen, const uint8_t *salt, size_t saltLen, const uint8_t *info, size_t infoLen, uint8_t *okm, size_t okmLen)HKDF key derivation function.Definition: hkdf.c:63 cryptoFreeMem#define cryptoFreeMem(p)Definition: crypto.h:861 cryptoAllocMem#define cryptoAllocMem(size)Definition: crypto.h:856 HashAlgoCommon interface for hash algorithms.Definition: crypto.h:1151 hkdfExtracterror_t hkdfExtract(const HashAlgo *hash, const uint8_t *ikm, size_t ikmLen, const uint8_t *salt, size_t saltLen, uint8_t *prk)HKDF extract step.Definition: hkdf.c:97 osMemset#define osMemset(p, value, length)Definition: os_port.h:138 hmacInit__weak_func error_t hmacInit(HmacContext *context, const HashAlgo *hash, const void *key, size_t keyLen)Initialize HMAC calculation.Definition: hmac.c:140 NO_ERROR@ NO_ERRORSuccess.Definition: error.h:44 hmac.hHMAC (Keyed-Hashing for Message Authentication) Copyright © 2023 Oryx Embedded SARL. All Rights Reserved. Contact Terms Privacy