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0a5d68aba5
Some crypto libraries can return in these functions (e.g., if a specific hash function is disabled), so we better provide the caller a chance to check whether the call failed. The return values are not yet used anywhere, but they will be needed for future changes.
77 lines
1.9 KiB
C
77 lines
1.9 KiB
C
/*
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* SHA1 T-PRF for EAP-FAST
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* Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Alternatively, this software may be distributed under the terms of BSD
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* license.
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*
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* See README and COPYING for more details.
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*/
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#include "includes.h"
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#include "common.h"
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#include "sha1.h"
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#include "crypto.h"
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/**
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* sha1_t_prf - EAP-FAST Pseudo-Random Function (T-PRF)
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* @key: Key for PRF
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* @key_len: Length of the key in bytes
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* @label: A unique label for each purpose of the PRF
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* @seed: Seed value to bind into the key
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* @seed_len: Length of the seed
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* @buf: Buffer for the generated pseudo-random key
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* @buf_len: Number of bytes of key to generate
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* Returns: 0 on success, -1 of failure
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*
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* This function is used to derive new, cryptographically separate keys from a
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* given key for EAP-FAST. T-PRF is defined in RFC 4851, Section 5.5.
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*/
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int sha1_t_prf(const u8 *key, size_t key_len, const char *label,
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const u8 *seed, size_t seed_len, u8 *buf, size_t buf_len)
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{
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unsigned char counter = 0;
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size_t pos, plen;
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u8 hash[SHA1_MAC_LEN];
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size_t label_len = os_strlen(label);
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u8 output_len[2];
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const unsigned char *addr[5];
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size_t len[5];
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addr[0] = hash;
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len[0] = 0;
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addr[1] = (unsigned char *) label;
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len[1] = label_len + 1;
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addr[2] = seed;
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len[2] = seed_len;
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addr[3] = output_len;
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len[3] = 2;
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addr[4] = &counter;
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len[4] = 1;
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output_len[0] = (buf_len >> 8) & 0xff;
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output_len[1] = buf_len & 0xff;
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pos = 0;
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while (pos < buf_len) {
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counter++;
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plen = buf_len - pos;
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if (hmac_sha1_vector(key, key_len, 5, addr, len, hash))
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return -1;
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if (plen >= SHA1_MAC_LEN) {
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os_memcpy(&buf[pos], hash, SHA1_MAC_LEN);
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pos += SHA1_MAC_LEN;
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} else {
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os_memcpy(&buf[pos], hash, plen);
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break;
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}
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len[0] = SHA1_MAC_LEN;
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}
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return 0;
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}
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