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/*
* EAP server/peer: EAP-GPSK shared routines
* Copyright (c) 2006-2007, 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 "eap_defs.h"
#include "aes_wrap.h"
#include "crypto.h"
#ifdef EAP_GPSK_SHA256
#include "sha256.h"
#endif /* EAP_GPSK_SHA256 */
#include "eap_gpsk_common.h"


/**
* eap_gpsk_supported_ciphersuite - Check whether ciphersuite is supported
* @vendor: CSuite/Vendor
* @specifier: CSuite/Specifier
* Returns: 1 if ciphersuite is support, or 0 if not
*/
int eap_gpsk_supported_ciphersuite(int vendor, int specifier)
{
if (vendor == EAP_GPSK_VENDOR_IETF &&
specifier == EAP_GPSK_CIPHER_AES)
return 1;
#ifdef EAP_GPSK_SHA256
if (vendor == EAP_GPSK_VENDOR_IETF &&
specifier == EAP_GPSK_CIPHER_SHA256)
return 1;
#endif /* EAP_GPSK_SHA256 */
return 0;
}


static int eap_gpsk_gkdf_cmac(const u8 *psk /* Y */,
const u8 *data /* Z */, size_t data_len,
u8 *buf, size_t len /* X */)
{
u8 *opos;
size_t i, n, hashlen, left, clen;
u8 ibuf[2], hash[16];
const u8 *addr[2];
size_t vlen[2];

hashlen = sizeof(hash);
/* M_i = MAC_Y (i || Z); (MAC = AES-CMAC-128) */
addr[0] = ibuf;
vlen[0] = sizeof(ibuf);
addr[1] = data;
vlen[1] = data_len;

opos = buf;
left = len;
n = (len + hashlen - 1) / hashlen;
for (i = 1; i <= n; i++) {
WPA_PUT_BE16(ibuf, i);
omac1_aes_128_vector(psk, 2, addr, vlen, hash);
clen = left > hashlen ? hashlen : left;
os_memcpy(opos, hash, clen);
opos += clen;
left -= clen;
}

return 0;
}


#ifdef EAP_GPSK_SHA256
static int eap_gpsk_gkdf_sha256(const u8 *psk /* Y */,
const u8 *data /* Z */, size_t data_len,
u8 *buf, size_t len /* X */)
{
u8 *opos;
size_t i, n, hashlen, left, clen;
u8 ibuf[2], hash[SHA256_MAC_LEN];
const u8 *addr[2];
size_t vlen[2];

hashlen = SHA256_MAC_LEN;
/* M_i = MAC_Y (i || Z); (MAC = HMAC-SHA256) */
addr[0] = ibuf;
vlen[0] = sizeof(ibuf);
addr[1] = data;
vlen[1] = data_len;

opos = buf;
left = len;
n = (len + hashlen - 1) / hashlen;
for (i = 1; i <= n; i++) {
WPA_PUT_BE16(ibuf, i);
hmac_sha256_vector(psk, 32, 2, addr, vlen, hash);
clen = left > hashlen ? hashlen : left;
os_memcpy(opos, hash, clen);
opos += clen;
left -= clen;
}

return 0;
}
#endif /* EAP_GPSK_SHA256 */


static int eap_gpsk_derive_keys_helper(u32 csuite_specifier,
u8 *kdf_out, size_t kdf_out_len,
const u8 *psk, size_t psk_len,
const u8 *seed, size_t seed_len,
u8 *msk, u8 *emsk,
u8 *sk, size_t sk_len,
u8 *pk, size_t pk_len)
{
u8 mk[32], *pos, *data;
size_t data_len, mk_len;
int (*gkdf)(const u8 *psk, const u8 *data, size_t data_len,
u8 *buf, size_t len);

gkdf = NULL;
switch (csuite_specifier) {
case EAP_GPSK_CIPHER_AES:
gkdf = eap_gpsk_gkdf_cmac;
mk_len = 16;
break;
#ifdef EAP_GPSK_SHA256
case EAP_GPSK_CIPHER_SHA256:
gkdf = eap_gpsk_gkdf_sha256;
mk_len = SHA256_MAC_LEN;
break;
#endif /* EAP_GPSK_SHA256 */
default:
return -1;
}

if (psk_len < mk_len)
return -1;

data_len = 2 + psk_len + 6 + seed_len;
data = os_malloc(data_len);
if (data == NULL)
return -1;
pos = data;
WPA_PUT_BE16(pos, psk_len);
pos += 2;
os_memcpy(pos, psk, psk_len);
pos += psk_len;
WPA_PUT_BE32(pos, EAP_GPSK_VENDOR_IETF); /* CSuite/Vendor = IETF */
pos += 4;
WPA_PUT_BE16(pos, csuite_specifier); /* CSuite/Specifier */
pos += 2;
os_memcpy(pos, seed, seed_len); /* inputString */
wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: Data to MK derivation",
data, data_len);

if (gkdf(psk, data, data_len, mk, mk_len) < 0) {
os_free(data);
return -1;
}
os_free(data);
wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: MK", mk, mk_len);

if (gkdf(mk, seed, seed_len, kdf_out, kdf_out_len) < 0)
return -1;

pos = kdf_out;
wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: MSK", pos, EAP_MSK_LEN);
os_memcpy(msk, pos, EAP_MSK_LEN);
pos += EAP_MSK_LEN;

wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: EMSK", pos, EAP_EMSK_LEN);
os_memcpy(emsk, pos, EAP_EMSK_LEN);
pos += EAP_EMSK_LEN;

wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: SK", pos, sk_len);
os_memcpy(sk, pos, sk_len);
pos += sk_len;

if (pk) {
wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: PK", pos, pk_len);
os_memcpy(pk, pos, pk_len);
}

return 0;
}


static int eap_gpsk_derive_keys_aes(const u8 *psk, size_t psk_len,
const u8 *seed, size_t seed_len,
u8 *msk, u8 *emsk, u8 *sk, size_t *sk_len,
u8 *pk, size_t *pk_len)
{
#define EAP_GPSK_SK_LEN_AES 16
#define EAP_GPSK_PK_LEN_AES 16
u8 kdf_out[EAP_MSK_LEN + EAP_EMSK_LEN + EAP_GPSK_SK_LEN_AES +
EAP_GPSK_PK_LEN_AES];

/*
* inputString = RAND_Peer || ID_Peer || RAND_Server || ID_Server
* (= seed)
* KS = 16, PL = psk_len, CSuite_Sel = 0x00000000 0x0001
* MK = GKDF-16 (PSK[0..15], PL || PSK || CSuite_Sel || inputString)
* MSK = GKDF-160 (MK, inputString)[0..63]
* EMSK = GKDF-160 (MK, inputString)[64..127]
* SK = GKDF-160 (MK, inputString)[128..143]
* PK = GKDF-160 (MK, inputString)[144..159]
* zero = 0x00 || 0x00 || ... || 0x00 (16 times)
* Method-ID = GKDF-16 (zero, "Method ID" || EAP_Method_Type ||
* CSuite_Sel || inputString)
*/

*sk_len = EAP_GPSK_SK_LEN_AES;
*pk_len = EAP_GPSK_PK_LEN_AES;

return eap_gpsk_derive_keys_helper(EAP_GPSK_CIPHER_AES,
kdf_out, sizeof(kdf_out),
psk, psk_len, seed, seed_len,
msk, emsk, sk, *sk_len,
pk, *pk_len);
}


#ifdef EAP_GPSK_SHA256
static int eap_gpsk_derive_keys_sha256(const u8 *psk, size_t psk_len,
const u8 *seed, size_t seed_len,
u8 *msk, u8 *emsk,
u8 *sk, size_t *sk_len)
{
#define EAP_GPSK_SK_LEN_SHA256 SHA256_MAC_LEN
#define EAP_GPSK_PK_LEN_SHA256 SHA256_MAC_LEN
u8 kdf_out[EAP_MSK_LEN + EAP_EMSK_LEN + EAP_GPSK_SK_LEN_SHA256 +
EAP_GPSK_PK_LEN_SHA256];

/*
* inputString = RAND_Peer || ID_Peer || RAND_Server || ID_Server
* (= seed)
* KS = 32, PL = psk_len, CSuite_Sel = 0x00000000 0x0002
* MK = GKDF-32 (PSK[0..31], PL || PSK || CSuite_Sel || inputString)
* MSK = GKDF-160 (MK, inputString)[0..63]
* EMSK = GKDF-160 (MK, inputString)[64..127]
* SK = GKDF-160 (MK, inputString)[128..159]
* zero = 0x00 || 0x00 || ... || 0x00 (32 times)
* Method-ID = GKDF-16 (zero, "Method ID" || EAP_Method_Type ||
* CSuite_Sel || inputString)
*/

*sk_len = EAP_GPSK_SK_LEN_SHA256;

return eap_gpsk_derive_keys_helper(EAP_GPSK_CIPHER_SHA256,
kdf_out, sizeof(kdf_out),
psk, psk_len, seed, seed_len,
msk, emsk, sk, *sk_len,
NULL, 0);
}
#endif /* EAP_GPSK_SHA256 */


/**
* eap_gpsk_derive_keys - Derive EAP-GPSK keys
* @psk: Pre-shared key
* @psk_len: Length of psk in bytes
* @vendor: CSuite/Vendor
* @specifier: CSuite/Specifier
* @rand_peer: 32-byte RAND_Peer
* @rand_server: 32-byte RAND_Server
* @id_peer: ID_Peer
* @id_peer_len: Length of ID_Peer
* @id_server: ID_Server
* @id_server_len: Length of ID_Server
* @msk: Buffer for 64-byte MSK
* @emsk: Buffer for 64-byte EMSK
* @sk: Buffer for SK (at least EAP_GPSK_MAX_SK_LEN bytes)
* @sk_len: Buffer for returning length of SK
* @pk: Buffer for PK (at least EAP_GPSK_MAX_PK_LEN bytes)
* @pk_len: Buffer for returning length of PK
* Returns: 0 on success, -1 on failure
*/
int eap_gpsk_derive_keys(const u8 *psk, size_t psk_len, int vendor,
int specifier,
const u8 *rand_peer, const u8 *rand_server,
const u8 *id_peer, size_t id_peer_len,
const u8 *id_server, size_t id_server_len,
u8 *msk, u8 *emsk, u8 *sk, size_t *sk_len,
u8 *pk, size_t *pk_len)
{
u8 *seed, *pos;
size_t seed_len;
int ret;

wpa_printf(MSG_DEBUG, "EAP-GPSK: Deriving keys (%d:%d)",
vendor, specifier);

if (vendor != EAP_GPSK_VENDOR_IETF)
return -1;

wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: PSK", psk, psk_len);

/* Seed = RAND_Peer || ID_Peer || RAND_Server || ID_Server */
seed_len = 2 * EAP_GPSK_RAND_LEN + id_server_len + id_peer_len;
seed = os_malloc(seed_len);
if (seed == NULL) {
wpa_printf(MSG_DEBUG, "EAP-GPSK: Failed to allocate memory "
"for key derivation");
return -1;
}

pos = seed;
os_memcpy(pos, rand_peer, EAP_GPSK_RAND_LEN);
pos += EAP_GPSK_RAND_LEN;
os_memcpy(pos, id_peer, id_peer_len);
pos += id_peer_len;
os_memcpy(pos, rand_server, EAP_GPSK_RAND_LEN);
pos += EAP_GPSK_RAND_LEN;
os_memcpy(pos, id_server, id_server_len);
pos += id_server_len;
wpa_hexdump(MSG_DEBUG, "EAP-GPSK: Seed", seed, seed_len);

switch (specifier) {
case EAP_GPSK_CIPHER_AES:
ret = eap_gpsk_derive_keys_aes(psk, psk_len, seed, seed_len,
msk, emsk, sk, sk_len,
pk, pk_len);
break;
#ifdef EAP_GPSK_SHA256
case EAP_GPSK_CIPHER_SHA256:
ret = eap_gpsk_derive_keys_sha256(psk, psk_len, seed, seed_len,
msk, emsk, sk, sk_len);
break;
#endif /* EAP_GPSK_SHA256 */
default:
wpa_printf(MSG_DEBUG, "EAP-GPSK: Unknown cipher %d:%d used in "
"key derivation", vendor, specifier);
ret = -1;
break;
}

os_free(seed);

return ret;
}


/**
* eap_gpsk_mic_len - Get the length of the MIC
* @vendor: CSuite/Vendor
* @specifier: CSuite/Specifier
* Returns: MIC length in bytes
*/
size_t eap_gpsk_mic_len(int vendor, int specifier)
{
if (vendor != EAP_GPSK_VENDOR_IETF)
return 0;

switch (specifier) {
case EAP_GPSK_CIPHER_AES:
return 16;
#ifdef EAP_GPSK_SHA256
case EAP_GPSK_CIPHER_SHA256:
return 32;
#endif /* EAP_GPSK_SHA256 */
default:
return 0;
}
}


static int eap_gpsk_compute_mic_aes(const u8 *sk, size_t sk_len,
const u8 *data, size_t len, u8 *mic)
{
if (sk_len != 16) {
wpa_printf(MSG_DEBUG, "EAP-GPSK: Invalid SK length %lu for "
"AES-CMAC MIC", (unsigned long) sk_len);
return -1;
}

return omac1_aes_128(sk, data, len, mic);
}


/**
* eap_gpsk_compute_mic - Compute EAP-GPSK MIC for an EAP packet
* @sk: Session key SK from eap_gpsk_derive_keys()
* @sk_len: SK length in bytes from eap_gpsk_derive_keys()
* @vendor: CSuite/Vendor
* @specifier: CSuite/Specifier
* @data: Input data to MIC
* @len: Input data length in bytes
* @mic: Buffer for the computed MIC, eap_gpsk_mic_len(cipher) bytes
* Returns: 0 on success, -1 on failure
*/
int eap_gpsk_compute_mic(const u8 *sk, size_t sk_len, int vendor,
int specifier, const u8 *data, size_t len, u8 *mic)
{
int ret;

if (vendor != EAP_GPSK_VENDOR_IETF)
return -1;

switch (specifier) {
case EAP_GPSK_CIPHER_AES:
ret = eap_gpsk_compute_mic_aes(sk, sk_len, data, len, mic);
break;
#ifdef EAP_GPSK_SHA256
case EAP_GPSK_CIPHER_SHA256:
hmac_sha256(sk, sk_len, data, len, mic);
ret = 0;
break;
#endif /* EAP_GPSK_SHA256 */
default:
wpa_printf(MSG_DEBUG, "EAP-GPSK: Unknown cipher %d:%d used in "
"MIC computation", vendor, specifier);
ret = -1;
break;
}

return ret;
}
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