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