/*
|
* HMAC-SHA384 KDF (RFC 5295) and HKDF-Expand(SHA384) (RFC 5869)
|
* Copyright (c) 2014-2017, Jouni Malinen <j@w1.fi>
|
*
|
* This software may be distributed under the terms of the BSD license.
|
* See README for more details.
|
*/
|
|
#include "includes.h"
|
|
#include "common.h"
|
#include "sha384.h"
|
|
|
/**
|
* hmac_sha384_kdf - HMAC-SHA384 based KDF (RFC 5295)
|
* @secret: Key for KDF
|
* @secret_len: Length of the key in bytes
|
* @label: A unique label for each purpose of the KDF or %NULL to select
|
* RFC 5869 HKDF-Expand() with arbitrary seed (= info)
|
* @seed: Seed value to bind into the key
|
* @seed_len: Length of the seed
|
* @out: Buffer for the generated pseudo-random key
|
* @outlen: Number of bytes of key to generate
|
* Returns: 0 on success, -1 on failure.
|
*
|
* This function is used to derive new, cryptographically separate keys from a
|
* given key in ERP. This KDF is defined in RFC 5295, Chapter 3.1.2. When used
|
* with label = NULL and seed = info, this matches HKDF-Expand() defined in
|
* RFC 5869, Chapter 2.3.
|
*/
|
int hmac_sha384_kdf(const u8 *secret, size_t secret_len,
|
const char *label, const u8 *seed, size_t seed_len,
|
u8 *out, size_t outlen)
|
{
|
u8 T[SHA384_MAC_LEN];
|
u8 iter = 1;
|
const unsigned char *addr[4];
|
size_t len[4];
|
size_t pos, clen;
|
|
addr[0] = T;
|
len[0] = SHA384_MAC_LEN;
|
if (label) {
|
addr[1] = (const unsigned char *) label;
|
len[1] = os_strlen(label) + 1;
|
} else {
|
addr[1] = (const u8 *) "";
|
len[1] = 0;
|
}
|
addr[2] = seed;
|
len[2] = seed_len;
|
addr[3] = &iter;
|
len[3] = 1;
|
|
if (hmac_sha384_vector(secret, secret_len, 3, &addr[1], &len[1], T) < 0)
|
return -1;
|
|
pos = 0;
|
for (;;) {
|
clen = outlen - pos;
|
if (clen > SHA384_MAC_LEN)
|
clen = SHA384_MAC_LEN;
|
os_memcpy(out + pos, T, clen);
|
pos += clen;
|
|
if (pos == outlen)
|
break;
|
|
if (iter == 255) {
|
os_memset(out, 0, outlen);
|
os_memset(T, 0, SHA384_MAC_LEN);
|
return -1;
|
}
|
iter++;
|
|
if (hmac_sha384_vector(secret, secret_len, 4, addr, len, T) < 0)
|
{
|
os_memset(out, 0, outlen);
|
os_memset(T, 0, SHA384_MAC_LEN);
|
return -1;
|
}
|
}
|
|
os_memset(T, 0, SHA384_MAC_LEN);
|
return 0;
|
}
|
