1 /* Copyright (c) 2014, Google Inc. 2 * 3 * Permission to use, copy, modify, and/or distribute this software for any 4 * purpose with or without fee is hereby granted, provided that the above 5 * copyright notice and this permission notice appear in all copies. 6 * 7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ 14 15 #ifndef OPENSSL_HEADER_HKDF_H 16 #define OPENSSL_HEADER_HKDF_H 17 18 #include <openssl/base.h> 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 69