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/*
* Copyright (C) 2014 Martin Willi
* Copyright (C) 2014 revosec AG
*
* 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 "tls_aead.h"
#include <crypto/iv/iv_gen_rand.h>
typedef struct private_tls_aead_t private_tls_aead_t;
/**
* Private data of an tls_aead_t object.
*/
struct private_tls_aead_t {
/**
* Public tls_aead_t interface.
*/
tls_aead_t public;
/**
* traditional crypter
*/
crypter_t *crypter;
/**
* traditional signer
*/
signer_t *signer;
/**
* IV generator
*/
iv_gen_t *iv_gen;
};
/**
* Associated header data to create signature over
*/
typedef struct __attribute__((__packed__)) {
uint64_t seq;
uint8_t type;
uint16_t version;
uint16_t length;
} sigheader_t;
METHOD(tls_aead_t, encrypt, bool,
private_tls_aead_t *this, tls_version_t version, tls_content_type_t type,
uint64_t seq, chunk_t *data)
{
chunk_t assoc, mac, padding, iv;
uint8_t bs, padlen;
sigheader_t hdr;
hdr.type = type;
htoun64(&hdr.seq, seq);
htoun16(&hdr.version, version);
htoun16(&hdr.length, data->len);
assoc = chunk_from_thing(hdr);
if (!this->signer->get_signature(this->signer, assoc, NULL) ||
!this->signer->allocate_signature(this->signer, *data, &mac))
{
return FALSE;
}
bs = this->crypter->get_block_size(this->crypter);
padlen = pad_len(data->len + mac.len + 1, bs);
padding = chunk_alloca(padlen);
memset(padding.ptr, padlen, padding.len);
/* TLSv1.1 uses random IVs, prepended to record */
iv.len = this->crypter->get_iv_size(this->crypter);
iv = chunk_alloca(iv.len);
if (!this->iv_gen->get_iv(this->iv_gen, seq, iv.len, iv.ptr))
{
return FALSE;
}
*data = chunk_cat("mmcc", *data, mac, padding, chunk_from_thing(padlen));
/* encrypt inline */
if (!this->crypter->encrypt(this->crypter, *data, iv, NULL))
{
return FALSE;
}
/* prepend IV */
*data = chunk_cat("cm", iv, *data);
return TRUE;
}
METHOD(tls_aead_t, decrypt, bool,
private_tls_aead_t *this, tls_version_t version, tls_content_type_t type,
uint64_t seq, chunk_t *data)
{
chunk_t assoc, mac, iv;
uint8_t bs, padlen;
sigheader_t hdr;
size_t i;
iv.len = this->crypter->get_iv_size(this->crypter);
if (data->len < iv.len)
{
return FALSE;
}
iv.ptr = data->ptr;
*data = chunk_skip(*data, iv.len);
bs = this->crypter->get_block_size(this->crypter);
if (data->len < bs || data->len % bs)
{
return FALSE;
}
if (!this->crypter->decrypt(this->crypter, *data, iv, NULL))
{
return FALSE;
}
padlen = data->ptr[data->len - 1];
if (padlen < data->len)
{ /* If padding looks valid, remove it */
for (i = data->len - padlen - 1; i < data->len - 1; i++)
{
if (data->ptr[i] != padlen)
{
return FALSE;
}
}
data->len -= padlen + 1;
}
bs = this->signer->get_block_size(this->signer);
if (data->len < bs)
{
return FALSE;
}
mac = chunk_skip(*data, data->len - bs);
data->len -= bs;
hdr.type = type;
htoun64(&hdr.seq, seq);
htoun16(&hdr.version, version);
htoun16(&hdr.length, data->len);
assoc = chunk_from_thing(hdr);
if (!this->signer->get_signature(this->signer, assoc, NULL) ||
!this->signer->verify_signature(this->signer, *data, mac))
{
return FALSE;
}
return TRUE;
}
METHOD(tls_aead_t, get_mac_key_size, size_t,
private_tls_aead_t *this)
{
return this->signer->get_key_size(this->signer);
}
METHOD(tls_aead_t, get_encr_key_size, size_t,
private_tls_aead_t *this)
{
return this->crypter->get_key_size(this->crypter);
}
METHOD(tls_aead_t, get_iv_size, size_t,
private_tls_aead_t *this)
{
return 0;
}
METHOD(tls_aead_t, set_keys, bool,
private_tls_aead_t *this, chunk_t mac, chunk_t encr, chunk_t iv)
{
if (iv.len)
{
return FALSE;
}
return this->signer->set_key(this->signer, mac) &&
this->crypter->set_key(this->crypter, encr);
}
METHOD(tls_aead_t, destroy, void,
private_tls_aead_t *this)
{
this->iv_gen->destroy(this->iv_gen);
DESTROY_IF(this->crypter);
DESTROY_IF(this->signer);
free(this);
}
/**
* See header
*/
tls_aead_t *tls_aead_create_explicit(integrity_algorithm_t mac,
encryption_algorithm_t encr, size_t encr_size)
{
private_tls_aead_t *this;
INIT(this,
.public = {
.encrypt = _encrypt,
.decrypt = _decrypt,
.get_mac_key_size = _get_mac_key_size,
.get_encr_key_size = _get_encr_key_size,
.get_iv_size = _get_iv_size,
.set_keys = _set_keys,
.destroy = _destroy,
},
.crypter = lib->crypto->create_crypter(lib->crypto, encr, encr_size),
.signer = lib->crypto->create_signer(lib->crypto, mac),
.iv_gen = iv_gen_rand_create(),
);
if (!this->crypter || !this->signer)
{
destroy(this);
return NULL;
}
return &this->public;
}
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