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/*
* Copyright (C) 2013 Tobias Brunner
* 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 "pkcs7_encrypted_data.h"
#include <asn1/asn1.h>
#include <asn1/asn1_parser.h>
#include <asn1/oid.h>
#include <crypto/pkcs5.h>
#include <utils/debug.h>
typedef struct private_pkcs7_encrypted_data_t private_pkcs7_encrypted_data_t;
/**
* Private data of a PKCS#7 signed-data container.
*/
struct private_pkcs7_encrypted_data_t {
/**
* Implements pkcs7_t.
*/
pkcs7_t public;
/**
* Decrypted content
*/
chunk_t content;
/**
* Encrypted and encoded PKCS#7 encrypted-data
*/
chunk_t encoding;
};
/**
* Decrypt encrypted-data with available passwords
*/
static bool decrypt(pkcs5_t *pkcs5, chunk_t data, chunk_t *decrypted)
{
enumerator_t *enumerator;
shared_key_t *shared;
bool success = FALSE;
enumerator = lib->credmgr->create_shared_enumerator(lib->credmgr,
SHARED_PRIVATE_KEY_PASS, NULL, NULL);
while (enumerator->enumerate(enumerator, &shared, NULL, NULL))
{
if (pkcs5->decrypt(pkcs5, shared->get_key(shared), data, decrypted))
{
success = TRUE;
break;
}
}
enumerator->destroy(enumerator);
return success;
}
/**
* ASN.1 definition of the PKCS#7 encrypted-data type
*/
static const asn1Object_t encryptedDataObjects[] = {
{ 0, "encryptedData", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
{ 1, "version", ASN1_INTEGER, ASN1_BODY }, /* 1 */
{ 1, "encryptedContentInfo", ASN1_SEQUENCE, ASN1_OBJ }, /* 2 */
{ 2, "contentType", ASN1_OID, ASN1_BODY }, /* 3 */
{ 2, "contentEncryptionAlgorithm", ASN1_EOC, ASN1_RAW }, /* 4 */
{ 2, "encryptedContent", ASN1_CONTEXT_S_0, ASN1_BODY }, /* 5 */
{ 0, "exit", ASN1_EOC, ASN1_EXIT }
};
#define PKCS7_VERSION 1
#define PKCS7_CONTENT_TYPE 3
#define PKCS7_CONTENT_ENC_ALGORITHM 4
#define PKCS7_ENCRYPTED_CONTENT 5
/**
* Parse and decrypt encrypted-data
*/
static bool parse(private_pkcs7_encrypted_data_t *this, chunk_t content)
{
asn1_parser_t *parser;
chunk_t object;
int objectID, version;
bool success = FALSE;
chunk_t encrypted = chunk_empty;
pkcs5_t *pkcs5 = NULL;
parser = asn1_parser_create(encryptedDataObjects, content);
while (parser->iterate(parser, &objectID, &object))
{
int level = parser->get_level(parser);
switch (objectID)
{
case PKCS7_VERSION:
version = object.len ? (int)*object.ptr : 0;
DBG2(DBG_LIB, " v%d", version);
if (version != 0)
{
DBG1(DBG_LIB, "encryptedData version is not 0");
goto end;
}
break;
case PKCS7_CONTENT_TYPE:
if (asn1_known_oid(object) != OID_PKCS7_DATA)
{
DBG1(DBG_LIB, "encrypted content not of type pkcs7 data");
goto end;
}
break;
case PKCS7_CONTENT_ENC_ALGORITHM:
pkcs5 = pkcs5_from_algorithmIdentifier(object, level + 1);
if (!pkcs5)
{
DBG1(DBG_LIB, "failed to detect PKCS#5 scheme");
goto end;
}
break;
case PKCS7_ENCRYPTED_CONTENT:
encrypted = object;
break;
}
}
success = parser->success(parser);
end:
parser->destroy(parser);
success = success && decrypt(pkcs5, encrypted, &this->content);
DESTROY_IF(pkcs5);
return success;
}
METHOD(container_t, get_type, container_type_t,
private_pkcs7_encrypted_data_t *this)
{
return CONTAINER_PKCS7_ENCRYPTED_DATA;
}
METHOD(container_t, get_data, bool,
private_pkcs7_encrypted_data_t *this, chunk_t *data)
{
if (this->content.len)
{
*data = chunk_clone(this->content);
return TRUE;
}
return FALSE;
}
METHOD(container_t, get_encoding, bool,
private_pkcs7_encrypted_data_t *this, chunk_t *data)
{
*data = chunk_clone(this->encoding);
return TRUE;
}
METHOD(container_t, destroy, void,
private_pkcs7_encrypted_data_t *this)
{
free(this->content.ptr);
free(this->encoding.ptr);
free(this);
}
/**
* Generic constructor
*/
static private_pkcs7_encrypted_data_t* create_empty()
{
private_pkcs7_encrypted_data_t *this;
INIT(this,
.public = {
.container = {
.get_type = _get_type,
.create_signature_enumerator = (void*)enumerator_create_empty,
.get_data = _get_data,
.get_encoding = _get_encoding,
.destroy = _destroy,
},
.create_cert_enumerator = (void*)enumerator_create_empty,
.get_attribute = (void*)return_false,
},
);
return this;
}
/**
* See header.
*/
pkcs7_t *pkcs7_encrypted_data_load(chunk_t encoding, chunk_t content)
{
private_pkcs7_encrypted_data_t *this = create_empty();
this->encoding = chunk_clone(encoding);
if (!parse(this, content))
{
destroy(this);
return NULL;
}
return &this->public;
}
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