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/*
* Copyright (C) 2009-2011 Martin Willi
* 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 "simaka_crypto.h"
#include "simaka_manager.h"
#include <utils/debug.h>
/** length of the k_encr key */
#define KENCR_LEN 16
/** length of the k_auth key */
#define KAUTH_LEN 16
/** length of the MSK */
#define MSK_LEN 64
/** length of the EMSK */
#define EMSK_LEN 64
typedef struct private_simaka_crypto_t private_simaka_crypto_t;
/**
* Private data of an simaka_crypto_t object.
*/
struct private_simaka_crypto_t {
/**
* Public simaka_crypto_t interface.
*/
simaka_crypto_t public;
/**
* EAP type this crypto is used, SIM or AKA
*/
eap_type_t type;
/**
* signer to create/verify AT_MAC
*/
signer_t *signer;
/**
* crypter to encrypt/decrypt AT_ENCR_DATA
*/
crypter_t *crypter;
/**
* hasher used in key derivation
*/
hasher_t *hasher;
/**
* PRF function used in key derivation
*/
prf_t *prf;
/**
* Random number generator to generate nonces
*/
rng_t *rng;
/**
* Have k_encr/k_auth been derived?
*/
bool derived;
};
METHOD(simaka_crypto_t, get_signer, signer_t*,
private_simaka_crypto_t *this)
{
return this->derived ? this->signer : NULL;
}
METHOD(simaka_crypto_t, get_crypter, crypter_t*,
private_simaka_crypto_t *this)
{
return this->derived ? this->crypter : NULL;
}
METHOD(simaka_crypto_t, get_rng, rng_t*,
private_simaka_crypto_t *this)
{
return this->rng;
}
/**
* Call SIM/AKA key hook
*/
static void call_hook(private_simaka_crypto_t *this, chunk_t encr, chunk_t auth)
{
simaka_manager_t *mgr;
switch (this->type)
{
case EAP_SIM:
mgr = lib->get(lib, "sim-manager");
break;
case EAP_AKA:
mgr = lib->get(lib, "aka-manager");
break;
default:
return;
}
mgr->key_hook(mgr, encr, auth);
}
METHOD(simaka_crypto_t, derive_keys_full, bool,
private_simaka_crypto_t *this, identification_t *id,
chunk_t data, chunk_t *mk, chunk_t *msk)
{
chunk_t str, k_encr, k_auth;
int i;
/* For SIM: MK = SHA1(Identity|n*Kc|NONCE_MT|Version List|Selected Version)
* For AKA: MK = SHA1(Identity|IK|CK) */
if (!this->hasher->get_hash(this->hasher, id->get_encoding(id), NULL) ||
!this->hasher->allocate_hash(this->hasher, data, mk))
{
return FALSE;
}
DBG3(DBG_LIB, "MK %B", mk);
/* K_encr | K_auth | MSK | EMSK = prf() | prf() | prf() | prf() */
if (!this->prf->set_key(this->prf, *mk))
{
chunk_clear(mk);
return FALSE;
}
str = chunk_alloca(this->prf->get_block_size(this->prf) * 3);
for (i = 0; i < 3; i++)
{
if (!this->prf->get_bytes(this->prf, chunk_empty,
str.ptr + str.len / 3 * i))
{
chunk_clear(mk);
return FALSE;
}
}
k_encr = chunk_create(str.ptr, KENCR_LEN);
k_auth = chunk_create(str.ptr + KENCR_LEN, KAUTH_LEN);
if (!this->signer->set_key(this->signer, k_auth) ||
!this->crypter->set_key(this->crypter, k_encr))
{
chunk_clear(mk);
return FALSE;
}
*msk = chunk_clone(chunk_create(str.ptr + KENCR_LEN + KAUTH_LEN, MSK_LEN));
DBG3(DBG_LIB, "K_encr %B\nK_auth %B\nMSK %B", &k_encr, &k_auth, msk);
call_hook(this, k_encr, k_auth);
this->derived = TRUE;
return TRUE;
}
METHOD(simaka_crypto_t, derive_keys_reauth, bool,
private_simaka_crypto_t *this, chunk_t mk)
{
chunk_t str, k_encr, k_auth;
int i;
/* K_encr | K_auth = prf() | prf() */
if (!this->prf->set_key(this->prf, mk))
{
return FALSE;
}
str = chunk_alloca(this->prf->get_block_size(this->prf) * 2);
for (i = 0; i < 2; i++)
{
if (!this->prf->get_bytes(this->prf, chunk_empty,
str.ptr + str.len / 2 * i))
{
return FALSE;
}
}
k_encr = chunk_create(str.ptr, KENCR_LEN);
k_auth = chunk_create(str.ptr + KENCR_LEN, KAUTH_LEN);
DBG3(DBG_LIB, "K_encr %B\nK_auth %B", &k_encr, &k_auth);
if (!this->signer->set_key(this->signer, k_auth) ||
!this->crypter->set_key(this->crypter, k_encr))
{
return FALSE;
}
call_hook(this, k_encr, k_auth);
this->derived = TRUE;
return TRUE;
}
METHOD(simaka_crypto_t, derive_keys_reauth_msk, bool,
private_simaka_crypto_t *this, identification_t *id, chunk_t counter,
chunk_t nonce_s, chunk_t mk, chunk_t *msk)
{
char xkey[HASH_SIZE_SHA1];
chunk_t str;
int i;
if (!this->hasher->get_hash(this->hasher, id->get_encoding(id), NULL) ||
!this->hasher->get_hash(this->hasher, counter, NULL) ||
!this->hasher->get_hash(this->hasher, nonce_s, NULL) ||
!this->hasher->get_hash(this->hasher, mk, xkey))
{
return FALSE;
}
/* MSK | EMSK = prf() | prf() | prf() | prf() */
if (!this->prf->set_key(this->prf, chunk_create(xkey, sizeof(xkey))))
{
return FALSE;
}
str = chunk_alloca(this->prf->get_block_size(this->prf) * 2);
for (i = 0; i < 2; i++)
{
if (!this->prf->get_bytes(this->prf, chunk_empty,
str.ptr + str.len / 2 * i))
{
return FALSE;
}
}
*msk = chunk_clone(chunk_create(str.ptr, MSK_LEN));
DBG3(DBG_LIB, "MSK %B", msk);
return TRUE;
}
METHOD(simaka_crypto_t, clear_keys, void,
private_simaka_crypto_t *this)
{
this->derived = FALSE;
}
METHOD(simaka_crypto_t, destroy, void,
private_simaka_crypto_t *this)
{
DESTROY_IF(this->rng);
DESTROY_IF(this->hasher);
DESTROY_IF(this->prf);
DESTROY_IF(this->signer);
DESTROY_IF(this->crypter);
free(this);
}
/**
* See header
*/
simaka_crypto_t *simaka_crypto_create(eap_type_t type)
{
private_simaka_crypto_t *this;
INIT(this,
.public = {
.get_signer = _get_signer,
.get_crypter = _get_crypter,
.get_rng = _get_rng,
.derive_keys_full = _derive_keys_full,
.derive_keys_reauth = _derive_keys_reauth,
.derive_keys_reauth_msk = _derive_keys_reauth_msk,
.clear_keys = _clear_keys,
.destroy = _destroy,
},
.type = type,
.rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK),
.hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1),
.prf = lib->crypto->create_prf(lib->crypto, PRF_FIPS_SHA1_160),
.signer = lib->crypto->create_signer(lib->crypto, AUTH_HMAC_SHA1_128),
.crypter = lib->crypto->create_crypter(lib->crypto, ENCR_AES_CBC, 16),
);
if (!this->rng || !this->hasher || !this->prf ||
!this->signer || !this->crypter)
{
DBG1(DBG_LIB, "unable to use %N, missing algorithms",
eap_type_names, type);
destroy(this);
return NULL;
}
return &this->public;
}
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