| 1 | /* |
| 2 | * SHA1-based PRF |
| 3 | * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi> |
| 4 | * |
| 5 | * This software may be distributed under the terms of the BSD license. |
| 6 | * See README for more details. |
| 7 | */ |
| 8 | |
| 9 | #include "includes.h" |
| 10 | |
| 11 | #include "common.h" |
| 12 | #include "sha1.h" |
| 13 | #include "crypto.h" |
| 14 | |
| 15 | |
| 16 | /** |
| 17 | * sha1_prf - SHA1-based Pseudo-Random Function (PRF) (IEEE 802.11i, 8.5.1.1) |
| 18 | * @key: Key for PRF |
| 19 | * @key_len: Length of the key in bytes |
| 20 | * @label: A unique label for each purpose of the PRF |
| 21 | * @data: Extra data to bind into the key |
| 22 | * @data_len: Length of the data |
| 23 | * @buf: Buffer for the generated pseudo-random key |
| 24 | * @buf_len: Number of bytes of key to generate |
| 25 | * Returns: 0 on success, -1 of failure |
| 26 | * |
| 27 | * This function is used to derive new, cryptographically separate keys from a |
| 28 | * given key (e.g., PMK in IEEE 802.11i). |
| 29 | */ |
| 30 | int sha1_prf(const u8 *key, size_t key_len, const char *label, |
| 31 | const u8 *data, size_t data_len, u8 *buf, size_t buf_len) |
| 32 | { |
| 33 | u8 counter = 0; |
| 34 | size_t pos, plen; |
| 35 | u8 hash[SHA1_MAC_LEN]; |
| 36 | size_t label_len = os_strlen(label) + 1; |
| 37 | const unsigned char *addr[3]; |
| 38 | size_t len[3]; |
| 39 | |
| 40 | addr[0] = (u8 *) label; |
| 41 | len[0] = label_len; |
| 42 | addr[1] = data; |
| 43 | len[1] = data_len; |
| 44 | addr[2] = &counter; |
| 45 | len[2] = 1; |
| 46 | |
| 47 | pos = 0; |
| 48 | while (pos < buf_len) { |
| 49 | plen = buf_len - pos; |
| 50 | if (plen >= SHA1_MAC_LEN) { |
| 51 | if (hmac_sha1_vector(key, key_len, 3, addr, len, |
| 52 | &buf[pos])) |
| 53 | return -1; |
| 54 | pos += SHA1_MAC_LEN; |
| 55 | } else { |
| 56 | if (hmac_sha1_vector(key, key_len, 3, addr, len, |
| 57 | hash)) |
| 58 | return -1; |
| 59 | os_memcpy(&buf[pos], hash, plen); |
| 60 | break; |
| 61 | } |
| 62 | counter++; |
| 63 | } |
| 64 | |
| 65 | return 0; |
| 66 | } |