179 lines
4.6 KiB
C
179 lines
4.6 KiB
C
/*
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* Copyright (C) 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 "simaka_crypto.h"
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#include <daemon.h>
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/** length of the k_encr key */
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#define KENCR_LEN 16
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/** length of the k_auth key */
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#define KAUTH_LEN 16
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/** length of the MSK */
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#define MSK_LEN 64
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/** length of the EMSK */
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#define EMSK_LEN 64
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typedef struct private_simaka_crypto_t private_simaka_crypto_t;
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/**
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* Private data of an simaka_crypto_t object.
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*/
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struct private_simaka_crypto_t {
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/**
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* Public simaka_crypto_t interface.
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*/
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simaka_crypto_t public;
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/**
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* signer to create/verify AT_MAC
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*/
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signer_t *signer;
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/**
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* crypter to encrypt/decrypt AT_ENCR_DATA
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*/
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crypter_t *crypter;
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/**
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* hasher used in key derivation
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*/
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hasher_t *hasher;
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/**
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* PRF function used in key derivation
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*/
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prf_t *prf;
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/**
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* Random number generator to generate nonces
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*/
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rng_t *rng;
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/**
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* Have k_encr/k_auth been derived?
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*/
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bool derived;
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};
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/**
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* Implementation of simaka_crypto_t.get_signer
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*/
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static signer_t* get_signer(private_simaka_crypto_t *this)
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{
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return this->derived ? this->signer : NULL;
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}
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/**
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* Implementation of simaka_crypto_t.get_crypter
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*/
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static crypter_t* get_crypter(private_simaka_crypto_t *this)
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{
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return this->derived ? this->crypter : NULL;
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}
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/**
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* Implementation of simaka_crypto_t.get_rng
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*/
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static rng_t* get_rng(private_simaka_crypto_t *this)
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{
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return this->rng;
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}
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/**
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* Implementation of simaka_crypto_t.derive_keys_full
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*/
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static chunk_t derive_keys_full(private_simaka_crypto_t *this,
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identification_t *id, chunk_t data)
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{
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char mk[HASH_SIZE_SHA1], k_encr[KENCR_LEN], k_auth[KAUTH_LEN];
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chunk_t str, msk;
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int i;
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/* For SIM: MK = SHA1(Identity|n*Kc|NONCE_MT|Version List|Selected Version)
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* For AKA: MK = SHA1(Identity|IK|CK) */
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this->hasher->get_hash(this->hasher, id->get_encoding(id), NULL);
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this->hasher->get_hash(this->hasher, data, mk);
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DBG3(DBG_IKE, "MK %b", mk, HASH_SIZE_SHA1);
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/* K_encr | K_auth | MSK | EMSK = prf() | prf() | prf() | prf() */
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this->prf->set_key(this->prf, chunk_create(mk, HASH_SIZE_SHA1));
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str = chunk_alloca(this->prf->get_block_size(this->prf) * 3);
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for (i = 0; i < 3; i++)
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{
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this->prf->get_bytes(this->prf, chunk_empty, str.ptr + str.len / 3 * i);
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}
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memcpy(k_encr, str.ptr, KENCR_LEN);
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str = chunk_skip(str, KENCR_LEN);
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memcpy(k_auth, str.ptr, KAUTH_LEN);
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str = chunk_skip(str, KAUTH_LEN);
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this->signer->set_key(this->signer, chunk_create(k_auth, KAUTH_LEN));
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this->crypter->set_key(this->crypter, chunk_create(k_encr, KENCR_LEN));
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msk = chunk_clone(chunk_create(str.ptr, MSK_LEN));
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DBG3(DBG_IKE, "K_encr %b\nK_auth %b\nMSK %B",
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k_encr, KENCR_LEN, k_auth, KAUTH_LEN, &msk);
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this->derived = TRUE;
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return msk;
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}
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/**
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* Implementation of simaka_crypto_t.destroy.
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*/
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static void destroy(private_simaka_crypto_t *this)
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{
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DESTROY_IF(this->rng);
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DESTROY_IF(this->hasher);
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DESTROY_IF(this->prf);
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DESTROY_IF(this->signer);
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DESTROY_IF(this->crypter);
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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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simaka_crypto_t *simaka_crypto_create()
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{
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private_simaka_crypto_t *this = malloc_thing(private_simaka_crypto_t);
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this->public.get_signer = (signer_t*(*)(simaka_crypto_t*))get_signer;
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this->public.get_crypter = (crypter_t*(*)(simaka_crypto_t*))get_crypter;
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this->public.get_rng = (rng_t*(*)(simaka_crypto_t*))get_rng;
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this->public.derive_keys_full = (chunk_t(*)(simaka_crypto_t*, identification_t *id, chunk_t data))derive_keys_full;
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this->public.destroy = (void(*)(simaka_crypto_t*))destroy;
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this->derived = FALSE;
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this->rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
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this->hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1);
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this->prf = lib->crypto->create_prf(lib->crypto, PRF_FIPS_SHA1_160);
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this->signer = lib->crypto->create_signer(lib->crypto, AUTH_HMAC_SHA1_128);
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this->crypter = lib->crypto->create_crypter(lib->crypto, ENCR_AES_CBC, 16);
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if (!this->rng || !this->hasher || !this->prf ||
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!this->signer || !this->crypter)
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{
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DBG1(DBG_IKE, "unable to use EAP-SIM, missing algorithms");
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destroy(this);
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return NULL;
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}
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return &this->public;
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}
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