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/*! \file milenage.c
* 3GPP AKA - Milenage algorithm (3GPP TS 35.205, .206, .207, .208) */
/*
* Copyright (c) 2006-2007 <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.
*
* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
*
* This file implements an example authentication algorithm defined for 3GPP
* AKA. This can be used to implement a simple HLR/AuC into hlr_auc_gw to allow
* EAP-AKA to be tested properly with real USIM cards.
*
* This implementations assumes that the r1..r5 and c1..c5 constants defined in
* TS 35.206 are used, i.e., r1=64, r2=0, r3=32, r4=64, r5=96, c1=00..00,
* c2=00..01, c3=00..02, c4=00..04, c5=00..08. The block cipher is assumed to
* be AES (Rijndael).
*/
#include "includes.h"
#include "common.h"
#include "aes_wrap.h"
#include "milenage.h"
#include <osmocom/crypt/auth.h>
/**
* milenage_f1 - Milenage f1 and f1* algorithms
* @opc: OPc = 128-bit value derived from OP and K
* @k: K = 128-bit subscriber key
* @_rand: RAND = 128-bit random challenge
* @sqn: SQN = 48-bit sequence number
* @amf: AMF = 16-bit authentication management field
* @mac_a: Buffer for MAC-A = 64-bit network authentication code, or %NULL
* @mac_s: Buffer for MAC-S = 64-bit resync authentication code, or %NULL
* Returns: 0 on success, -1 on failure
*/
int milenage_f1(const u8 *opc, const u8 *k, const u8 *_rand,
const u8 *sqn, const u8 *amf, u8 *mac_a, u8 *mac_s)
{
u8 tmp1[16], tmp2[16], tmp3[16];
int i;
/* tmp1 = TEMP = E_K(RAND XOR OP_C) */
for (i = 0; i < 16; i++)
tmp1[i] = _rand[i] ^ opc[i];
if (aes_128_encrypt_block(k, tmp1, tmp1))
return -1;
/* tmp2 = IN1 = SQN || AMF || SQN || AMF */
os_memcpy(tmp2, sqn, 6);
os_memcpy(tmp2 + 6, amf, 2);
os_memcpy(tmp2 + 8, tmp2, 8);
/* OUT1 = E_K(TEMP XOR rot(IN1 XOR OP_C, r1) XOR c1) XOR OP_C */
/* rotate (tmp2 XOR OP_C) by r1 (= 0x40 = 8 bytes) */
for (i = 0; i < 16; i++)
tmp3[(i + 8) % 16] = tmp2[i] ^ opc[i];
/* XOR with TEMP = E_K(RAND XOR OP_C) */
for (i = 0; i < 16; i++)
tmp3[i] ^= tmp1[i];
/* XOR with c1 (= ..00, i.e., NOP) */
/* f1 || f1* = E_K(tmp3) XOR OP_c */
if (aes_128_encrypt_block(k, tmp3, tmp1))
return -1;
for (i = 0; i < 16; i++)
tmp1[i] ^= opc[i];
if (mac_a)
os_memcpy(mac_a, tmp1, 8); /* f1 */
if (mac_s)
os_memcpy(mac_s, tmp1 + 8, 8); /* f1* */
return 0;
}
/**
* milenage_f2345 - Milenage f2, f3, f4, f5, f5* algorithms
* @opc: OPc = 128-bit value derived from OP and K
* @k: K = 128-bit subscriber key
* @_rand: RAND = 128-bit random challenge
* @res: Buffer for RES = 64-bit signed response (f2), or %NULL
* @ck: Buffer for CK = 128-bit confidentiality key (f3), or %NULL
* @ik: Buffer for IK = 128-bit integrity key (f4), or %NULL
* @ak: Buffer for AK = 48-bit anonymity key (f5), or %NULL
* @akstar: Buffer for AK = 48-bit anonymity key (f5*), or %NULL
* Returns: 0 on success, -1 on failure
*/
int milenage_f2345(const u8 *opc, const u8 *k, const u8 *_rand,
u8 *res, u8 *ck, u8 *ik, u8 *ak, u8 *akstar)
{
u8 tmp1[16], tmp2[16], tmp3[16];
int i;
/* tmp2 = TEMP = E_K(RAND XOR OP_C) */
for (i = 0; i < 16; i++)
tmp1[i] = _rand[i] ^ opc[i];
if (aes_128_encrypt_block(k, tmp1, tmp2))
return -1;
/* OUT2 = E_K(rot(TEMP XOR OP_C, r2) XOR c2) XOR OP_C */
/* OUT3 = E_K(rot(TEMP XOR OP_C, r3) XOR c3) XOR OP_C */
/* OUT4 = E_K(rot(TEMP XOR OP_C, r4) XOR c4) XOR OP_C */
/* OUT5 = E_K(rot(TEMP XOR OP_C, r5) XOR c5) XOR OP_C */
/* f2 and f5 */
/* rotate by r2 (= 0, i.e., NOP) */
for (i = 0; i < 16; i++)
tmp1[i] = tmp2[i] ^ opc[i];
tmp1[15] ^= 1; /* XOR c2 (= ..01) */
/* f5 || f2 = E_K(tmp1) XOR OP_c */
if (aes_128_encrypt_block(k, tmp1, tmp3))
return -1;
for (i = 0; i < 16; i++)
tmp3[i] ^= opc[i];
if (res)
os_memcpy(res, tmp3 + 8, 8); /* f2 */
if (ak)
os_memcpy(ak, tmp3, 6); /* f5 */
/* f3 */
if (ck) {
/* rotate by r3 = 0x20 = 4 bytes */
for (i = 0; i < 16; i++)
tmp1[(i + 12) % 16] = tmp2[i] ^ opc[i];
tmp1[15] ^= 2; /* XOR c3 (= ..02) */
if (aes_128_encrypt_block(k, tmp1, ck))
return -1;
for (i = 0; i < 16; i++)
ck[i] ^= opc[i];
}
/* f4 */
if (ik) {
/* rotate by r4 = 0x40 = 8 bytes */
for (i = 0; i < 16; i++)
tmp1[(i + 8) % 16] = tmp2[i] ^ opc[i];
tmp1[15] ^= 4; /* XOR c4 (= ..04) */
if (aes_128_encrypt_block(k, tmp1, ik))
return -1;
for (i = 0; i < 16; i++)
ik[i] ^= opc[i];
}
/* f5* */
if (akstar) {
/* rotate by r5 = 0x60 = 12 bytes */
for (i = 0; i < 16; i++)
tmp1[(i + 4) % 16] = tmp2[i] ^ opc[i];
tmp1[15] ^= 8; /* XOR c5 (= ..08) */
if (aes_128_encrypt_block(k, tmp1, tmp1))
return -1;
for (i = 0; i < 6; i++)
akstar[i] = tmp1[i] ^ opc[i];
}
return 0;
}
/**
* milenage_generate - Generate AKA AUTN,IK,CK,RES
* @opc: OPc = 128-bit operator variant algorithm configuration field (encr.)
* @amf: AMF = 16-bit authentication management field
* @k: K = 128-bit subscriber key
* @sqn: SQN = 48-bit sequence number
* @_rand: RAND = 128-bit random challenge
* @autn: Buffer for AUTN = 128-bit authentication token
* @ik: Buffer for IK = 128-bit integrity key (f4), or %NULL
* @ck: Buffer for CK = 128-bit confidentiality key (f3), or %NULL
* @res: Buffer for RES = 64-bit signed response (f2), or %NULL
* @res_len: Max length for res; set to used length or 0 on failure
*/
void milenage_generate(const u8 *opc, const u8 *amf, const u8 *k,
const u8 *sqn, const u8 *_rand, u8 *autn, u8 *ik,
u8 *ck, u8 *res, size_t *res_len)
{
int i;
u8 mac_a[8], ak[6];
if (*res_len < 8) {
*res_len = 0;
return;
}
if (milenage_f1(opc, k, _rand, sqn, amf, mac_a, NULL) ||
milenage_f2345(opc, k, _rand, res, ck, ik, ak, NULL)) {
*res_len = 0;
return;
}
*res_len = 8;
/* AUTN = (SQN ^ AK) || AMF || MAC */
for (i = 0; i < 6; i++)
autn[i] = sqn[i] ^ ak[i];
os_memcpy(autn + 6, amf, 2);
os_memcpy(autn + 8, mac_a, 8);
}
/**
* milenage_auts - Milenage AUTS validation
* @opc: OPc = 128-bit operator variant algorithm configuration field (encr.)
* @k: K = 128-bit subscriber key
* @_rand: RAND = 128-bit random challenge
* @auts: AUTS = 112-bit authentication token from client
* @sqn: Buffer for SQN = 48-bit sequence number
* Returns: 0 = success (sqn filled), -1 on failure
*/
int milenage_auts(const u8 *opc, const u8 *k, const u8 *_rand, const u8 *auts,
u8 *sqn)
{
u8 amf[2] = { 0x00, 0x00 }; /* TS 33.102 v7.0.0, 6.3.3 */
u8 ak[6], mac_s[8];
int i;
if (milenage_f2345(opc, k, _rand, NULL, NULL, NULL, NULL, ak))
return -1;
for (i = 0; i < 6; i++)
sqn[i] = auts[i] ^ ak[i];
if (milenage_f1(opc, k, _rand, sqn, amf, NULL, mac_s) ||
memcmp(mac_s, auts + 6, 8) != 0)
return -1;
return 0;
}
/**
* gsm_milenage - Generate GSM-Milenage (3GPP TS 55.205) authentication triplet
* @opc: OPc = 128-bit operator variant algorithm configuration field (encr.)
* @k: K = 128-bit subscriber key
* @_rand: RAND = 128-bit random challenge
* @sres: Buffer for SRES = 32-bit SRES
* @kc: Buffer for Kc = 64-bit Kc
* Returns: 0 on success, -1 on failure
*/
int gsm_milenage(const u8 *opc, const u8 *k, const u8 *_rand, u8 *sres, u8 *kc)
{
u8 res[8], ck[16], ik[16];
int i;
if (milenage_f2345(opc, k, _rand, res, ck, ik, NULL, NULL))
return -1;
osmo_auth_c3(kc, ck, ik);
#ifdef GSM_MILENAGE_ALT_SRES
os_memcpy(sres, res, 4);
#else /* GSM_MILENAGE_ALT_SRES */
for (i = 0; i < 4; i++)
sres[i] = res[i] ^ res[i + 4];
#endif /* GSM_MILENAGE_ALT_SRES */
return 0;
}
/**
* milenage_generate - Generate AKA AUTN,IK,CK,RES
* @opc: OPc = 128-bit operator variant algorithm configuration field (encr.)
* @k: K = 128-bit subscriber key
* @sqn: SQN = 48-bit sequence number
* @_rand: RAND = 128-bit random challenge
* @autn: AUTN = 128-bit authentication token
* @ik: Buffer for IK = 128-bit integrity key (f4), or %NULL
* @ck: Buffer for CK = 128-bit confidentiality key (f3), or %NULL
* @res: Buffer for RES = 64-bit signed response (f2), or %NULL
* @res_len: Variable that will be set to RES length
* @auts: 112-bit buffer for AUTS
* Returns: 0 on success, -1 on failure, or -2 on synchronization failure
*/
int milenage_check(const u8 *opc, const u8 *k, const u8 *sqn, const u8 *_rand,
const u8 *autn, u8 *ik, u8 *ck, u8 *res, size_t *res_len,
u8 *auts)
{
int i;
u8 mac_a[8], ak[6], rx_sqn[6];
const u8 *amf;
wpa_hexdump(MSG_DEBUG, "Milenage: AUTN", autn, 16);
wpa_hexdump(MSG_DEBUG, "Milenage: RAND", _rand, 16);
if (milenage_f2345(opc, k, _rand, res, ck, ik, ak, NULL))
return -1;
*res_len = 8;
wpa_hexdump_key(MSG_DEBUG, "Milenage: RES", res, *res_len);
wpa_hexdump_key(MSG_DEBUG, "Milenage: CK", ck, 16);
wpa_hexdump_key(MSG_DEBUG, "Milenage: IK", ik, 16);
wpa_hexdump_key(MSG_DEBUG, "Milenage: AK", ak, 6);
/* AUTN = (SQN ^ AK) || AMF || MAC */
for (i = 0; i < 6; i++)
rx_sqn[i] = autn[i] ^ ak[i];
wpa_hexdump(MSG_DEBUG, "Milenage: SQN", rx_sqn, 6);
if (os_memcmp(rx_sqn, sqn, 6) <= 0) {
u8 auts_amf[2] = { 0x00, 0x00 }; /* TS 33.102 v7.0.0, 6.3.3 */
if (milenage_f2345(opc, k, _rand, NULL, NULL, NULL, NULL, ak))
return -1;
wpa_hexdump_key(MSG_DEBUG, "Milenage: AK*", ak, 6);
for (i = 0; i < 6; i++)
auts[i] = sqn[i] ^ ak[i];
if (milenage_f1(opc, k, _rand, sqn, auts_amf, NULL, auts + 6))
return -1;
wpa_hexdump(MSG_DEBUG, "Milenage: AUTS", auts, 14);
return -2;
}
amf = autn + 6;
wpa_hexdump(MSG_DEBUG, "Milenage: AMF", amf, 2);
if (milenage_f1(opc, k, _rand, rx_sqn, amf, mac_a, NULL))
return -1;
wpa_hexdump(MSG_DEBUG, "Milenage: MAC_A", mac_a, 8);
if (os_memcmp(mac_a, autn + 8, 8) != 0) {
wpa_printf(MSG_DEBUG, "Milenage: MAC mismatch");
wpa_hexdump(MSG_DEBUG, "Milenage: Received MAC_A",
autn + 8, 8);
return -1;
}
return 0;
}
int milenage_opc_gen(u8 *opc, const u8 *k, const u8 *op)
{
int i;
/* Encrypt OP using K */
if (aes_128_encrypt_block(k, op, opc))
return -1;
/* XOR the resulting Ek(OP) with OP */
for (i = 0; i < 16; i++)
opc[i] = opc[i] ^ op[i];
return 0;
}
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