/**
* sha384_prf_bits - IEEE Std 802.11ac-2013, 11.6.1.7.2 Key derivation function
* @key: Key for KDF
* @key_len: Length of the key in bytes
* @label: A unique label for each purpose of the PRF
* @data: Extra data to bind into the key
* @data_len: Length of the data
* @buf: Buffer for the generated pseudo-random key
* @buf_len: Number of bits of key to generate
*
* This function is used to derive new, cryptographically separate keys from a
* given key. If the requested buf_len is not divisible by eight, the least
* significant 1-7 bits of the last octet in the output are not part of the
* requested output.
*/
void sha384_prf_bits(const u8 *key, size_t key_len, const char *label,
const u8 *data, size_t data_len, u8 *buf,
size_t buf_len_bits)
{
u16 counter = 1;
size_t pos, plen;
u8 hash[SHA384_MAC_LEN];
const u8 *addr[4];
size_t len[4];
u8 counter_le[2], length_le[2];
size_t buf_len = (buf_len_bits + 7) / 8;
addr[0] = counter_le;
len[0] = 2;
addr[1] = (u8 *) label;
len[1] = os_strlen(label);
addr[2] = data;
len[2] = data_len;
addr[3] = length_le;
len[3] = sizeof(length_le);
WPA_PUT_LE16(length_le, buf_len_bits);
pos = 0;
while (pos < buf_len) {
plen = buf_len - pos;
WPA_PUT_LE16(counter_le, counter);
if (plen >= SHA384_MAC_LEN) {
hmac_sha384_vector(key, key_len, 4, addr, len,
&buf[pos]);
pos += SHA384_MAC_LEN;
} else {
hmac_sha384_vector(key, key_len, 4, addr, len, hash);
os_memcpy(&buf[pos], hash, plen);
pos += plen;
break;
}
counter++;
}
/*
* Mask out unused bits in the last octet if it does not use all the
* bits.
*/
if (buf_len_bits % 8) {
u8 mask = 0xff << (8 - buf_len_bits % 8);
buf[pos - 1] &= mask;
}
os_memset(hash, 0, sizeof(hash));
}
/**
* rsn_pmkid_suite_b_192 - Calculate PMK identifier for Suite B AKM
* @kck: Key confirmation key
* @kck_len: Length of kck in bytes
* @aa: Authenticator address
* @spa: Supplicant address
* @pmkid: Buffer for PMKID
* Returns: 0 on success, -1 on failure
*
* IEEE Std 802.11ac-2013 - 11.6.1.3 Pairwise key hierarchy
* PMKID = Truncate(HMAC-SHA-384(KCK, "PMK Name" || AA || SPA))
*/
int rsn_pmkid_suite_b_192(const u8 *kck, size_t kck_len, const u8 *aa,
const u8 *spa, u8 *pmkid)
{
char *title = "PMK Name";
const u8 *addr[3];
const size_t len[3] = { 8, ETH_ALEN, ETH_ALEN };
unsigned char hash[SHA384_MAC_LEN];
addr[0] = (u8 *) title;
addr[1] = aa;
addr[2] = spa;
if (hmac_sha384_vector(kck, kck_len, 3, addr, len, hash) < 0)
return -1;
os_memcpy(pmkid, hash, PMKID_LEN);
return 0;
}
