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Implement PKCS#7 enveloped-data parsing and decryption

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This commit is contained in:
Martin Willi 2012-11-27 10:32:54 +01:00
parent 98bbe0760f
commit d7aa09104f
4 changed files with 434 additions and 0 deletions
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1
src/libstrongswan/plugins/pkcs7/Makefile.am
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@ -12,6 +12,7 @@ endif
libstrongswan_pkcs7_la_SOURCES = \
pkcs7_generic.h pkcs7_generic.c \
pkcs7_signed_data.h pkcs7_signed_data.c \
pkcs7_enveloped_data.h pkcs7_enveloped_data.c \
pkcs7_data.h pkcs7_data.c \
pkcs7_plugin.h pkcs7_plugin.c

394
src/libstrongswan/plugins/pkcs7/pkcs7_enveloped_data.c Normal file
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@ -0,0 +1,394 @@
/*
* Copyright (C) 2012 Martin Willi
* Copyright (C) 2012 revosec AG
* Copyright (C) 2012 Tobias Brunner
* Copyright (C) 2002-2008 Andreas Steffen
* Copyright (C) 2005 Jan Hutter, Martin Willi
* Hochschule fuer Technik Rapperswil, Switzerland
*
* 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_enveloped_data.h"
#include <asn1/asn1.h>
#include <asn1/asn1_parser.h>
#include <asn1/oid.h>
#include <credentials/certificates/x509.h>
#include <utils/debug.h>
typedef struct private_pkcs7_enveloped_data_t private_pkcs7_enveloped_data_t;
/**
* Private data of a PKCS#7 signed-data container.
*/
struct private_pkcs7_enveloped_data_t {
/**
* Implements pkcs7_t.
*/
pkcs7_t public;
/**
* Decrypted content
*/
chunk_t content;
/**
* Encrypted and encoded PKCS#7 enveloped-data
*/
chunk_t encoding;
};
/**
* ASN.1 definition of the PKCS#7 envelopedData type
*/
static const asn1Object_t envelopedDataObjects[] = {
{ 0, "envelopedData", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
{ 1, "version", ASN1_INTEGER, ASN1_BODY }, /* 1 */
{ 1, "recipientInfos", ASN1_SET, ASN1_LOOP }, /* 2 */
{ 2, "recipientInfo", ASN1_SEQUENCE, ASN1_BODY }, /* 3 */
{ 3, "version", ASN1_INTEGER, ASN1_BODY }, /* 4 */
{ 3, "issuerAndSerialNumber", ASN1_SEQUENCE, ASN1_BODY }, /* 5 */
{ 4, "issuer", ASN1_SEQUENCE, ASN1_OBJ }, /* 6 */
{ 4, "serial", ASN1_INTEGER, ASN1_BODY }, /* 7 */
{ 3, "encryptionAlgorithm", ASN1_EOC, ASN1_RAW }, /* 8 */
{ 3, "encryptedKey", ASN1_OCTET_STRING, ASN1_BODY }, /* 9 */
{ 1, "end loop", ASN1_EOC, ASN1_END }, /* 10 */
{ 1, "encryptedContentInfo", ASN1_SEQUENCE, ASN1_OBJ }, /* 11 */
{ 2, "contentType", ASN1_OID, ASN1_BODY }, /* 12 */
{ 2, "contentEncryptionAlgorithm", ASN1_EOC, ASN1_RAW }, /* 13 */
{ 2, "encryptedContent", ASN1_CONTEXT_S_0, ASN1_BODY }, /* 14 */
{ 0, "exit", ASN1_EOC, ASN1_EXIT }
};
#define PKCS7_VERSION 1
#define PKCS7_RECIPIENT_INFO_VERSION 4
#define PKCS7_ISSUER 6
#define PKCS7_SERIAL_NUMBER 7
#define PKCS7_ENCRYPTION_ALG 8
#define PKCS7_ENCRYPTED_KEY 9
#define PKCS7_CONTENT_TYPE 12
#define PKCS7_CONTENT_ENC_ALGORITHM 13
#define PKCS7_ENCRYPTED_CONTENT 14
/**
* Find a private key for issuerAndSerialNumber
*/
static private_key_t *find_private(identification_t *issuer,
identification_t *serial)
{
enumerator_t *enumerator;
certificate_t *cert;
public_key_t *public;
private_key_t *private = NULL;
identification_t *id;
chunk_t fp;
enumerator = lib->credmgr->create_cert_enumerator(lib->credmgr,
CERT_X509, KEY_RSA, serial, FALSE);
while (enumerator->enumerate(enumerator, &cert))
{
if (issuer->equals(issuer, cert->get_issuer(cert)))
{
public = cert->get_public_key(cert);
if (public)
{
if (public->get_fingerprint(public, KEYID_PUBKEY_SHA1, &fp))
{
id = identification_create_from_encoding(ID_KEY_ID, fp);
private = lib->credmgr->get_private(lib->credmgr,
KEY_ANY, id, NULL);
id->destroy(id);
}
public->destroy(public);
}
}
if (private)
{
break;
}
}
enumerator->destroy(enumerator);
return private;
}
/**
* Decrypt content using a private key from "issuer"
*/
static bool decrypt(private_key_t *private, chunk_t key, chunk_t iv, int oid,
chunk_t encrypted, chunk_t *plain)
{
encryption_algorithm_t alg;
chunk_t plain_key;
crypter_t *crypter;
size_t key_size;
alg = encryption_algorithm_from_oid(oid, &key_size);
if (alg == ENCR_UNDEFINED)
{
DBG1(DBG_LIB, "unsupported content encryption algorithm");
return FALSE;
}
if (!private->decrypt(private, ENCRYPT_RSA_PKCS1, key, &plain_key))
{
DBG1(DBG_LIB, "symmetric key could not be decrypted with rsa");
return FALSE;
}
crypter = lib->crypto->create_crypter(lib->crypto, alg, key_size / 8);
if (!crypter)
{
DBG1(DBG_LIB, "crypter %N-%d not available",
encryption_algorithm_names, alg, key_size);
free(plain_key.ptr);
return FALSE;
}
if (plain_key.len != crypter->get_key_size(crypter))
{
DBG1(DBG_LIB, "symmetric key length %d is wrong", plain_key.len);
free(plain_key.ptr);
crypter->destroy(crypter);
return FALSE;
}
if (iv.len != crypter->get_iv_size(crypter))
{
DBG1(DBG_LIB, "IV length %d is wrong", iv.len);
free(plain_key.ptr);
crypter->destroy(crypter);
return FALSE;
}
if (!crypter->set_key(crypter, plain_key) ||
!crypter->decrypt(crypter, encrypted, iv, plain))
{
free(plain_key.ptr);
crypter->destroy(crypter);
return FALSE;
}
DBG4(DBG_LIB, "decrypted content with padding: %B", plain);
free(plain_key.ptr);
crypter->destroy(crypter);
return TRUE;
}
/**
* Remove the padding from plain data
*/
static bool remove_padding(private_pkcs7_enveloped_data_t *this)
{
u_char *pos = this->content.ptr + this->content.len - 1;
u_char pattern = *pos;
size_t padding = pattern;
if (padding > this->content.len)
{
DBG1(DBG_LIB, "padding greater than data length");
return FALSE;
}
this->content.len -= padding;
while (padding-- > 0)
{
if (*pos-- != pattern)
{
DBG1(DBG_LIB, "wrong padding pattern");
return FALSE;
}
}
return TRUE;
}
/**
* Parse and decrypt enveloped-data
*/
static bool parse(private_pkcs7_enveloped_data_t *this, chunk_t content)
{
asn1_parser_t *parser;
chunk_t object;
int objectID, version, alg = OID_UNKNOWN;
bool success = FALSE;
identification_t *issuer = NULL, *serial = NULL;
private_key_t *private = NULL;
chunk_t iv = chunk_empty, key = chunk_empty, encrypted = chunk_empty;
parser = asn1_parser_create(envelopedDataObjects, content);
parser->set_top_level(parser, 0);
while (parser->iterate(parser, &objectID, &object))
{
u_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, "envelopedData version is not 0");
goto end;
}
break;
case PKCS7_RECIPIENT_INFO_VERSION:
version = object.len ? (int)*object.ptr : 0;
DBG2(DBG_LIB, " v%d", version);
if (version != 0)
{
DBG1(DBG_LIB, "recipient info version is not 0");
goto end;
}
break;
case PKCS7_ISSUER:
if (!issuer)
{
issuer = identification_create_from_encoding(ID_DER_ASN1_DN,
object);
}
break;
case PKCS7_SERIAL_NUMBER:
if (!serial)
{
serial = identification_create_from_encoding(ID_KEY_ID,
object);
}
break;
case PKCS7_ENCRYPTION_ALG:
if (asn1_parse_algorithmIdentifier(object, level,
NULL) != OID_RSA_ENCRYPTION)
{
DBG1(DBG_LIB, "only rsa encryption supported");
goto end;
}
break;
case PKCS7_ENCRYPTED_KEY:
key = object;
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:
alg = asn1_parse_algorithmIdentifier(object, level, &iv);
if (!asn1_parse_simple_object(&iv, ASN1_OCTET_STRING,
level + 1, "IV"))
{
DBG1(DBG_LIB, "IV could not be parsed");
goto end;
}
break;
case PKCS7_ENCRYPTED_CONTENT:
encrypted = object;
break;
}
}
success = parser->success(parser);
end:
parser->destroy(parser);
if (!success)
{
goto failed;
}
success = FALSE;
if (!issuer)
{
goto failed;
}
private = find_private(issuer, serial);
if (!private)
{
DBG1(DBG_LIB, "no private key found to decrypt pkcs7");
goto failed;
}
if (!decrypt(private, key, iv, alg, encrypted, &this->content))
{
goto failed;
}
if (!remove_padding(this))
{
goto failed;
}
success = TRUE;
failed:
DESTROY_IF(issuer);
DESTROY_IF(serial);
DESTROY_IF(private);
return success;
}
METHOD(container_t, get_type, container_type_t,
private_pkcs7_enveloped_data_t *this)
{
return CONTAINER_PKCS7_ENVELOPED_DATA;
}
METHOD(container_t, create_signature_enumerator, enumerator_t*,
private_pkcs7_enveloped_data_t *this)
{
return enumerator_create_empty();
}
METHOD(container_t, get_data, bool,
private_pkcs7_enveloped_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_enveloped_data_t *this, chunk_t *data)
{
*data = chunk_clone(this->encoding);
return TRUE;
}
METHOD(container_t, destroy, void,
private_pkcs7_enveloped_data_t *this)
{
free(this->content.ptr);
free(this->encoding.ptr);
free(this);
}
/**
* See header.
*/
pkcs7_t *pkcs7_enveloped_data_load(chunk_t encoding, chunk_t content)
{
private_pkcs7_enveloped_data_t *this;
INIT(this,
.public = {
.container = {
.get_type = _get_type,
.create_signature_enumerator = _create_signature_enumerator,
.get_data = _get_data,
.get_encoding = _get_encoding,
.destroy = _destroy,
},
},
.encoding = chunk_clone(encoding),
);
if (!parse(this, content))
{
destroy(this);
return NULL;
}
return &this->public;
}

36
src/libstrongswan/plugins/pkcs7/pkcs7_enveloped_data.h Normal file
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@ -0,0 +1,36 @@
/*
* Copyright (C) 2012 Martin Willi
* Copyright (C) 2012 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.
*/
/**
* @defgroup pkcs7_enveloped_data pkcs7_enveloped_data
* @{ @ingroup pkcs7
*/
#ifndef PKCS7_ENVELOPED_DATA_H_
#define PKCS7_ENVELOPED_DATA_H_
#include <credentials/builder.h>
#include <credentials/containers/pkcs7.h>
/**
* Parse a PKCS#7 enveloped-data container.
*
* @param encoding full contentInfo encoding
* @param content DER encoded content from contentInfo
* @return CONTAINER_PKCS7_ENVELOPED_DATA container, NULL on failure
*/
pkcs7_t *pkcs7_enveloped_data_load(chunk_t encoding, chunk_t content);
#endif /** PKCS7_ENVELOPED_DATA_H_ @}*/

3
src/libstrongswan/plugins/pkcs7/pkcs7_generic.c
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@ -20,6 +20,7 @@
#include "pkcs7_generic.h"
#include "pkcs7_data.h"
#include "pkcs7_signed_data.h"
#include "pkcs7_enveloped_data.h"
#include <utils/debug.h>
#include <asn1/oid.h>
@ -82,6 +83,8 @@ end:
return pkcs7_data_load(blob, content);
case OID_PKCS7_SIGNED_DATA:
return pkcs7_signed_data_load(blob, content);
case OID_PKCS7_ENVELOPED_DATA:
return pkcs7_enveloped_data_load(blob, content);
default:
DBG1(DBG_ASN, "pkcs7 content type %d not supported", type);
return NULL;