hkdf.h (2740B)
1 // Copyright 2014 The BoringSSL Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #ifndef OPENSSL_HEADER_HKDF_H 16 #define OPENSSL_HEADER_HKDF_H 17 18 #include <openssl/base.h> // IWYU pragma: export 19 20 #if defined(__cplusplus) 21 extern "C" { 22 #endif 23 24 25 // HKDF. 26 27 28 // HKDF computes HKDF (as specified by RFC 5869) of initial keying material 29 // |secret| with |salt| and |info| using |digest|, and outputs |out_len| bytes 30 // to |out_key|. It returns one on success and zero on error. 31 // 32 // HKDF is an Extract-and-Expand algorithm. It does not do any key stretching, 33 // and as such, is not suited to be used alone to generate a key from a 34 // password. 35 OPENSSL_EXPORT int HKDF(uint8_t *out_key, size_t out_len, const EVP_MD *digest, 36 const uint8_t *secret, size_t secret_len, 37 const uint8_t *salt, size_t salt_len, 38 const uint8_t *info, size_t info_len); 39 40 // HKDF_extract computes a HKDF PRK (as specified by RFC 5869) from initial 41 // keying material |secret| and salt |salt| using |digest|, and outputs 42 // |out_len| bytes to |out_key|. The maximum output size is |EVP_MAX_MD_SIZE|. 43 // It returns one on success and zero on error. 44 // 45 // WARNING: This function orders the inputs differently from RFC 5869 46 // specification. Double-check which parameter is the secret/IKM and which is 47 // the salt when using. 48 OPENSSL_EXPORT int HKDF_extract(uint8_t *out_key, size_t *out_len, 49 const EVP_MD *digest, const uint8_t *secret, 50 size_t secret_len, const uint8_t *salt, 51 size_t salt_len); 52 53 // HKDF_expand computes a HKDF OKM (as specified by RFC 5869) of length 54 // |out_len| from the PRK |prk| and info |info| using |digest|, and outputs 55 // the result to |out_key|. It returns one on success and zero on error. 56 OPENSSL_EXPORT int HKDF_expand(uint8_t *out_key, size_t out_len, 57 const EVP_MD *digest, const uint8_t *prk, 58 size_t prk_len, const uint8_t *info, 59 size_t info_len); 60 61 62 #if defined(__cplusplus) 63 } // extern C 64 #endif 65 66 #define HKDF_R_OUTPUT_TOO_LARGE 100 67 68 #endif // OPENSSL_HEADER_HKDF_H