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/*
* Copyright (C) 2008-2009 Martin Willi
* HSR Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include "eap_aka_3gpp2_provider.h"
#include <daemon.h>
#include <credentials/keys/shared_key.h>
typedef struct private_eap_aka_3gpp2_provider_t private_eap_aka_3gpp2_provider_t;
/**
* Private data of an eap_aka_3gpp2_provider_t object.
*/
struct private_eap_aka_3gpp2_provider_t {
/**
* Public eap_aka_3gpp2_provider_t interface.
*/
eap_aka_3gpp2_provider_t public;
/**
* AKA functions
*/
eap_aka_3gpp2_functions_t *f;
/**
* time based SQN, we use the same for all peers
*/
char sqn[AKA_SQN_LEN];
};
/** Authentication management field */
static char amf[AKA_AMF_LEN] = {0x00, 0x01};
/**
* Get a shared key K from the credential database
*/
bool eap_aka_3gpp2_get_k(identification_t *id, char k[AKA_K_LEN])
{
shared_key_t *shared;
chunk_t key;
shared = lib->credmgr->get_shared(lib->credmgr, SHARED_EAP, id, NULL);
if (shared == NULL)
{
return FALSE;
}
key = shared->get_key(shared);
memset(k, '\0', AKA_K_LEN);
memcpy(k, key.ptr, min(key.len, AKA_K_LEN));
shared->destroy(shared);
return TRUE;
}
/**
* get SQN using current time
*/
void eap_aka_3gpp2_get_sqn(char sqn[AKA_SQN_LEN], int offset)
{
timeval_t time;
gettimeofday(&time, NULL);
/* set sqn to an integer containing 4 bytes seconds + 2 bytes usecs */
time.tv_sec = htonl(time.tv_sec + offset);
/* usec's are never larger than 0x000f423f, so we shift the 12 first bits */
time.tv_usec = htonl(time.tv_usec << 12);
memcpy(sqn, (char*)&time.tv_sec + sizeof(time_t) - 4, 4);
memcpy(sqn + 4, &time.tv_usec, 2);
}
METHOD(simaka_provider_t, get_quintuplet, bool,
private_eap_aka_3gpp2_provider_t *this, identification_t *id,
char rand[AKA_RAND_LEN], char xres[AKA_RES_MAX], int *xres_len,
char ck[AKA_CK_LEN], char ik[AKA_IK_LEN], char autn[AKA_AUTN_LEN])
{
rng_t *rng;
char mac[AKA_MAC_LEN], ak[AKA_AK_LEN], k[AKA_K_LEN];
/* generate RAND: we use a registered RNG, not f0() proposed in S.S0055 */
rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
if (!rng || !rng->get_bytes(rng, AKA_RAND_LEN, rand))
{
DBG1(DBG_IKE, "generating RAND for AKA failed");
DESTROY_IF(rng);
return FALSE;
}
rng->destroy(rng);
if (!eap_aka_3gpp2_get_k(id, k))
{
DBG1(DBG_IKE, "no EAP key found for %Y to authenticate with AKA", id);
return FALSE;
}
DBG3(DBG_IKE, "generated rand %b", rand, AKA_RAND_LEN);
DBG3(DBG_IKE, "using K %b", k, AKA_K_LEN);
/* MAC, AK, XRES as expected from client */
if (!this->f->f1(this->f, k, rand, this->sqn, amf, mac) ||
!this->f->f5(this->f, k, rand, ak) ||
!this->f->f2(this->f, k, rand, xres))
{
return FALSE;
}
*xres_len = AKA_RES_MAX;
/* AUTN = (SQN xor AK) || AMF || MAC */
memcpy(autn, this->sqn, AKA_SQN_LEN);
memxor(autn, ak, AKA_AK_LEN);
memcpy(autn + AKA_SQN_LEN, amf, AKA_AMF_LEN);
memcpy(autn + AKA_SQN_LEN + AKA_AMF_LEN, mac, AKA_MAC_LEN);
DBG3(DBG_IKE, "AUTN %b", autn, AKA_AUTN_LEN);
/* CK/IK */
if (!this->f->f3(this->f, k, rand, ck) ||
!this->f->f4(this->f, k, rand, ik))
{
return FALSE;
}
return TRUE;
}
METHOD(simaka_provider_t, resync, bool,
private_eap_aka_3gpp2_provider_t *this, identification_t *id,
char rand[AKA_RAND_LEN], char auts[AKA_AUTS_LEN])
{
char *sqn, *macs;
char aks[AKA_AK_LEN], k[AKA_K_LEN], amf[AKA_AMF_LEN], xmacs[AKA_MAC_LEN];
if (!eap_aka_3gpp2_get_k(id, k))
{
DBG1(DBG_IKE, "no EAP key found for %Y to authenticate with AKA", id);
return FALSE;
}
/* AUTHS = (AK xor SQN) | MAC */
sqn = auts;
macs = auts + AKA_SQN_LEN;
if (!this->f->f5star(this->f, k, rand, aks))
{
return FALSE;
}
memxor(sqn, aks, AKA_AK_LEN);
/* verify XMACS, AMF of zero is used in resynchronization */
memset(amf, 0, AKA_AMF_LEN);
if (!this->f->f1star(this->f, k, rand, sqn, amf, xmacs))
{
return FALSE;
}
if (!memeq_const(macs, xmacs, AKA_MAC_LEN))
{
DBG1(DBG_IKE, "received MACS does not match XMACS");
DBG3(DBG_IKE, "MACS %b XMACS %b",
macs, AKA_MAC_LEN, xmacs, AKA_MAC_LEN);
return FALSE;
}
/* update stored SQN to received SQN + 1 */
memcpy(this->sqn, sqn, AKA_SQN_LEN);
chunk_increment(chunk_create(this->sqn, AKA_SQN_LEN));
return TRUE;
}
METHOD(eap_aka_3gpp2_provider_t, destroy, void,
private_eap_aka_3gpp2_provider_t *this)
{
free(this);
}
/**
* See header
*/
eap_aka_3gpp2_provider_t *eap_aka_3gpp2_provider_create(
eap_aka_3gpp2_functions_t *f)
{
private_eap_aka_3gpp2_provider_t *this;
INIT(this,
.public = {
.provider = {
.get_triplet = (void*)return_false,
.get_quintuplet = _get_quintuplet,
.resync = _resync,
.is_pseudonym = (void*)return_null,
.gen_pseudonym = (void*)return_null,
.is_reauth = (void*)return_null,
.gen_reauth = (void*)return_null,
},
.destroy = _destroy,
},
.f = f,
);
/* use an offset to accept clock skew between client/server without resync */
eap_aka_3gpp2_get_sqn(this->sqn, 180);
return &this->public;
}
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