/*
* EAP server/peer: EAP-SAKE shared routines
* Copyright (c) 2006, Jouni Malinen <j@w1.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Alternatively, this software may be distributed under the terms of BSD
* license.
*
* See README and COPYING for more details.
*/
#include "includes.h"
#include "common.h"
#include "sha1.h"
#include "eap_defs.h"
#include "eap_sake_common.h"
static int eap_sake_parse_add_attr(struct eap_sake_parse_attr *attr,
const u8 *pos)
{
size_t i;
switch (pos[0]) {
case EAP_SAKE_AT_RAND_S:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_RAND_S");
if (pos[1] != 2 + EAP_SAKE_RAND_LEN) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_RAND_S with "
"invalid length %d", pos[1]);
return -1;
}
attr->rand_s = pos + 2;
break;
case EAP_SAKE_AT_RAND_P:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_RAND_P");
if (pos[1] != 2 + EAP_SAKE_RAND_LEN) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_RAND_P with "
"invalid length %d", pos[1]);
return -1;
}
attr->rand_p = pos + 2;
break;
case EAP_SAKE_AT_MIC_S:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MIC_S");
if (pos[1] != 2 + EAP_SAKE_MIC_LEN) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_MIC_S with "
"invalid length %d", pos[1]);
return -1;
}
attr->mic_s = pos + 2;
break;
case EAP_SAKE_AT_MIC_P:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MIC_P");
if (pos[1] != 2 + EAP_SAKE_MIC_LEN) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_MIC_P with "
"invalid length %d", pos[1]);
return -1;
}
attr->mic_p = pos + 2;
break;
case EAP_SAKE_AT_SERVERID:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SERVERID");
attr->serverid = pos + 2;
attr->serverid_len = pos[1] - 2;
break;
case EAP_SAKE_AT_PEERID:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PEERID");
attr->peerid = pos + 2;
attr->peerid_len = pos[1] - 2;
break;
case EAP_SAKE_AT_SPI_S:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SPI_S");
attr->spi_s = pos + 2;
attr->spi_s_len = pos[1] - 2;
break;
case EAP_SAKE_AT_SPI_P:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SPI_P");
attr->spi_p = pos + 2;
attr->spi_p_len = pos[1] - 2;
break;
case EAP_SAKE_AT_ANY_ID_REQ:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_ANY_ID_REQ");
if (pos[1] != 4) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid AT_ANY_ID_REQ"
" length %d", pos[1]);
return -1;
}
attr->any_id_req = pos + 2;
break;
case EAP_SAKE_AT_PERM_ID_REQ:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PERM_ID_REQ");
if (pos[1] != 4) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid "
"AT_PERM_ID_REQ length %d", pos[1]);
return -1;
}
attr->perm_id_req = pos + 2;
break;
case EAP_SAKE_AT_ENCR_DATA:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_ENCR_DATA");
attr->encr_data = pos + 2;
attr->encr_data_len = pos[1] - 2;
break;
case EAP_SAKE_AT_IV:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_IV");
attr->iv = pos + 2;
attr->iv_len = pos[1] - 2;
break;
case EAP_SAKE_AT_PADDING:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PADDING");
for (i = 2; i < pos[1]; i++) {
if (pos[i]) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_PADDING "
"with non-zero pad byte");
return -1;
}
}
break;
case EAP_SAKE_AT_NEXT_TMPID:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_NEXT_TMPID");
attr->next_tmpid = pos + 2;
attr->next_tmpid_len = pos[1] - 2;
break;
case EAP_SAKE_AT_MSK_LIFE:
wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_IV");
if (pos[1] != 6) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid "
"AT_MSK_LIFE length %d", pos[1]);
return -1;
}
attr->msk_life = pos + 2;
break;
default:
if (pos[0] < 128) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: Unknown non-skippable"
" attribute %d", pos[0]);
return -1;
}
wpa_printf(MSG_DEBUG, "EAP-SAKE: Ignoring unknown skippable "
"attribute %d", pos[0]);
break;
}
if (attr->iv && !attr->encr_data) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_IV included without "
"AT_ENCR_DATA");
return -1;
}
return 0;
}
/**
* eap_sake_parse_attributes - Parse EAP-SAKE attributes
* @buf: Packet payload (starting with the first attribute)
* @len: Payload length
* @attr: Structure to be filled with found attributes
* Returns: 0 on success or -1 on failure
*/
int eap_sake_parse_attributes(const u8 *buf, size_t len,
struct eap_sake_parse_attr *attr)
{
const u8 *pos = buf, *end = buf + len;
os_memset(attr, 0, sizeof(*attr));
while (pos < end) {
if (end - pos < 2) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: Too short attribute");
return -1;
}
if (pos[1] < 2) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid attribute "
"length (%d)", pos[1]);
return -1;
}
if (pos + pos[1] > end) {
wpa_printf(MSG_DEBUG, "EAP-SAKE: Attribute underflow");
return -1;
}
if (eap_sake_parse_add_attr(attr, pos))
return -1;
pos += pos[1];
}
return 0;
}
/**
* eap_sake_kdf - EAP-SAKE Key Derivation Function (KDF)
* @key: Key for KDF
* @key_len: Length of the key in bytes
* @label: A unique label for each purpose of the KDF
* @data: Extra data (start) to bind into the key
* @data_len: Length of the data
* @data2: Extra data (end) to bind into the key
* @data2_len: Length of the data2
* @buf: Buffer for the generated pseudo-random key
* @buf_len: Number of bytes of key to generate
*
* This function is used to derive new, cryptographically separate keys from a
* given key (e.g., SMS). This is identical to the PRF used in IEEE 802.11i.
*/
static void eap_sake_kdf(const u8 *key, size_t key_len, const char *label,
const u8 *data, size_t data_len,
const u8 *data2, size_t data2_len,
u8 *buf, size_t buf_len)
{
u8 counter = 0;
size_t pos, plen;
u8 hash[SHA1_MAC_LEN];
size_t label_len = os_strlen(label) + 1;
const unsigned char *addr[4];
size_t len[4];
addr[0] = (u8 *) label; /* Label | Y */
len[0] = label_len;
addr[1] = data; /* Msg[start] */
len[1] = data_len;
addr[2] = data2; /* Msg[end] */
len[2] = data2_len;
addr[3] = &counter; /* Length */
len[3] = 1;
pos = 0;
while (pos < buf_len) {
plen = buf_len - pos;
if (plen >= SHA1_MAC_LEN) {
hmac_sha1_vector(key, key_len, 4, addr, len,
&buf[pos]);
pos += SHA1_MAC_LEN;
} else {
hmac_sha1_vector(key, key_len, 4, addr, len,
hash);
os_memcpy(&buf[pos], hash, plen);
break;
}
counter++;
}
}
/**
* eap_sake_derive_keys - Derive EAP-SAKE keys
* @root_secret_a: 16-byte Root-Secret-A
* @root_secret_b: 16-byte Root-Secret-B
* @rand_s: 16-byte RAND_S
* @rand_p: 16-byte RAND_P
* @tek: Buffer for Temporary EAK Keys (TEK-Auth[16] | TEK-Cipher[16])
* @msk: Buffer for 64-byte MSK
* @emsk: Buffer for 64-byte EMSK
*
* This function derives EAP-SAKE keys as defined in RFC 4763, section 3.2.6.
*/
void eap_sake_derive_keys(const u8 *root_secret_a, const u8 *root_secret_b,
const u8 *rand_s, const u8 *rand_p, u8 *tek, u8 *msk,
u8 *emsk)
{
u8 sms_a[EAP_SAKE_SMS_LEN];
u8 sms_b[EAP_SAKE_SMS_LEN];
u8 key_buf[EAP_MSK_LEN + EAP_EMSK_LEN];
wpa_printf(MSG_DEBUG, "EAP-SAKE: Deriving keys");
wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: Root-Secret-A",
root_secret_a, EAP_SAKE_ROOT_SECRET_LEN);
eap_sake_kdf(root_secret_a, EAP_SAKE_ROOT_SECRET_LEN,
"SAKE Master Secret A",
rand_p, EAP_SAKE_RAND_LEN, rand_s, EAP_SAKE_RAND_LEN,
sms_a, EAP_SAKE_SMS_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: SMS-A", sms_a, EAP_SAKE_SMS_LEN);
eap_sake_kdf(sms_a, EAP_SAKE_SMS_LEN, "Transient EAP Key",
rand_s, EAP_SAKE_RAND_LEN, rand_p, EAP_SAKE_RAND_LEN,
tek, EAP_SAKE_TEK_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: TEK-Auth",
tek, EAP_SAKE_TEK_AUTH_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: TEK-Cipher",
tek + EAP_SAKE_TEK_AUTH_LEN, EAP_SAKE_TEK_CIPHER_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: Root-Secret-B",
root_secret_b, EAP_SAKE_ROOT_SECRET_LEN);
eap_sake_kdf(root_secret_b, EAP_SAKE_ROOT_SECRET_LEN,
"SAKE Master Secret B",
rand_p, EAP_SAKE_RAND_LEN, rand_s, EAP_SAKE_RAND_LEN,
sms_b, EAP_SAKE_SMS_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: SMS-B", sms_b, EAP_SAKE_SMS_LEN);
eap_sake_kdf(sms_b, EAP_SAKE_SMS_LEN, "Master Session Key",
rand_s, EAP_SAKE_RAND_LEN, rand_p, EAP_SAKE_RAND_LEN,
key_buf, sizeof(key_buf));
os_memcpy(msk, key_buf, EAP_MSK_LEN);
os_memcpy(emsk, key_buf + EAP_MSK_LEN, EAP_EMSK_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: MSK", msk, EAP_MSK_LEN);
wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: EMSK", emsk, EAP_EMSK_LEN);
}
/**
* eap_sake_compute_mic - Compute EAP-SAKE MIC for an EAP packet
* @tek_auth: 16-byte TEK-Auth
* @rand_s: 16-byte RAND_S
* @rand_p: 16-byte RAND_P
* @serverid: SERVERID
* @serverid_len: SERVERID length
* @peerid: PEERID
* @peerid_len: PEERID length
* @peer: MIC calculation for 0 = Server, 1 = Peer message
* @eap: EAP packet
* @eap_len: EAP packet length
* @mic_pos: MIC position in the EAP packet (must be [eap .. eap + eap_len])
* @mic: Buffer for the computed 16-byte MIC
*/
int eap_sake_compute_mic(const u8 *tek_auth,
const u8 *rand_s, const u8 *rand_p,
const u8 *serverid, size_t serverid_len,
const u8 *peerid, size_t peerid_len,
int peer, const u8 *eap, size_t eap_len,
const u8 *mic_pos, u8 *mic)
{
u8 _rand[2 * EAP_SAKE_RAND_LEN];
u8 *tmp, *pos;
size_t tmplen;
tmplen = serverid_len + 1 + peerid_len + 1 + eap_len;
tmp = os_malloc(tmplen);
if (tmp == NULL)
return -1;
pos = tmp;
if (peer) {
if (peerid) {
os_memcpy(pos, peerid, peerid_len);
pos += peerid_len;
}
*pos++ = 0x00;
if (serverid) {
os_memcpy(pos, serverid, serverid_len);
pos += serverid_len;
}
*pos++ = 0x00;
os_memcpy(_rand, rand_s, EAP_SAKE_RAND_LEN);
os_memcpy(_rand + EAP_SAKE_RAND_LEN, rand_p,
EAP_SAKE_RAND_LEN);
} else {
if (serverid) {
os_memcpy(pos, serverid, serverid_len);
pos += serverid_len;
}
*pos++ = 0x00;
if (peerid) {
os_memcpy(pos, peerid, peerid_len);
pos += peerid_len;
}
*pos++ = 0x00;
os_memcpy(_rand, rand_p, EAP_SAKE_RAND_LEN);
os_memcpy(_rand + EAP_SAKE_RAND_LEN, rand_s,
EAP_SAKE_RAND_LEN);
}
os_memcpy(pos, eap, eap_len);
os_memset(pos + (mic_pos - eap), 0, EAP_SAKE_MIC_LEN);
eap_sake_kdf(tek_auth, EAP_SAKE_TEK_AUTH_LEN,
peer ? "Peer MIC" : "Server MIC",
_rand, 2 * EAP_SAKE_RAND_LEN, tmp, tmplen,
mic, EAP_SAKE_MIC_LEN);
os_free(tmp);
return 0;
}