/*
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* SHA1-based PRF
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* Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi>
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*
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* This software may be distributed under the terms of the BSD license.
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* See README 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_prf - SHA1-based Pseudo-Random Function (PRF) (IEEE 802.11i, 8.5.1.1)
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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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* @data: Extra data to bind into the key
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* @data_len: Length of the data
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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 (e.g., PMK in IEEE 802.11i).
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*/
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int sha1_prf(const u8 *key, size_t key_len, const char *label,
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const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
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{
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u8 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) + 1;
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const unsigned char *addr[3];
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size_t len[3];
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addr[0] = (u8 *) label;
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len[0] = label_len;
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addr[1] = data;
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len[1] = data_len;
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addr[2] = &counter;
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len[2] = 1;
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pos = 0;
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while (pos < buf_len) {
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plen = buf_len - pos;
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if (plen >= SHA1_MAC_LEN) {
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if (hmac_sha1_vector(key, key_len, 3, addr, len,
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&buf[pos]))
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return -1;
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pos += SHA1_MAC_LEN;
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} else {
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if (hmac_sha1_vector(key, key_len, 3, addr, len,
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hash))
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return -1;
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os_memcpy(&buf[pos], hash, plen);
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break;
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}
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counter++;
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}
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os_memset(hash, 0, sizeof(hash));
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return 0;
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}
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