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strongswan/src/libstrongswan/crypto/pkcs5.c

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/*
* Copyright (C) 2012-2013 Tobias Brunner
* 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 "pkcs5.h"
#include <utils/debug.h>
#include <asn1/oid.h>
#include <asn1/asn1.h>
#include <asn1/asn1_parser.h>
#include <credentials/containers/pkcs12.h>
typedef struct private_pkcs5_t private_pkcs5_t;
/**
* Private data of a pkcs5_t object
*/
struct private_pkcs5_t {
/**
* Implements pkcs5_t.
*/
pkcs5_t public;
/**
* Salt used during encryption
*/
chunk_t salt;
/**
* Iterations for key derivation
*/
u_int64_t iterations;
/**
* Encryption algorithm
*/
encryption_algorithm_t encr;
/**
* Encryption key length
*/
size_t keylen;
/**
* Crypter
*/
crypter_t *crypter;
/**
* The encryption scheme
*/
enum {
PKCS5_SCHEME_PBES1,
PKCS5_SCHEME_PBES2,
PKCS5_SCHEME_PKCS12,
} scheme;
/**
* Data used for individual schemes
*/
union {
struct {
/**
* Hash algorithm
*/
hash_algorithm_t hash;
/**
* Hasher
*/
hasher_t *hasher;
} pbes1;
struct {
/**
* PRF algorithm
*/
pseudo_random_function_t prf_alg;
/**
* PRF
*/
prf_t * prf;
/**
* IV
*/
chunk_t iv;
} pbes2;
} data;
};
/**
* Verify padding of decrypted blob.
* Length of blob is adjusted accordingly.
*/
static bool verify_padding(chunk_t *blob)
{
u_int8_t padding, count;
padding = count = blob->ptr[blob->len - 1];
if (padding > 8)
{
return FALSE;
}
for (; blob->len && count; --blob->len, --count)
{
if (blob->ptr[blob->len - 1] != padding)
{
return FALSE;
}
}
return TRUE;
}
/**
* Prototype for key derivation functions.
*/
typedef bool (*kdf_t)(private_pkcs5_t *this, chunk_t password, chunk_t key);
/**
* Try to decrypt the given data with the given password using the given
* key derivation function. keymat is where the kdf function writes the key
* to, key and iv point to the actual keys and initialization vectors resp.
*/
static bool decrypt_generic(private_pkcs5_t *this, chunk_t password,
chunk_t data, chunk_t *decrypted, kdf_t kdf,
chunk_t keymat, chunk_t key, chunk_t iv)
{
if (!kdf(this, password, keymat))
{
return FALSE;
}
if (!this->crypter->set_key(this->crypter, key) ||
!this->crypter->decrypt(this->crypter, data, iv, decrypted))
{
memwipe(keymat.ptr, keymat.len);
return FALSE;
}
memwipe(keymat.ptr, keymat.len);
if (verify_padding(decrypted))
{
return TRUE;
}
chunk_free(decrypted);
return FALSE;
}
/**
* KDF as used by PKCS#12
*/
static bool pkcs12_kdf(private_pkcs5_t *this, chunk_t password, chunk_t keymat)
{
chunk_t key, iv;
key = chunk_create(keymat.ptr, this->keylen);
iv = chunk_create(keymat.ptr + this->keylen, keymat.len - this->keylen);
return pkcs12_derive_key(this->data.pbes1.hash, password, this->salt,
this->iterations, PKCS12_KEY_ENCRYPTION, key) &&
pkcs12_derive_key(this->data.pbes1.hash, password, this->salt,
this->iterations, PKCS12_KEY_IV, iv);
}
/**
* Function F of PBKDF2
*/
static bool pbkdf2_f(chunk_t block, prf_t *prf, chunk_t seed,
u_int64_t iterations)
{
chunk_t u;
u_int64_t i;
u = chunk_alloca(prf->get_block_size(prf));
if (!prf->get_bytes(prf, seed, u.ptr))
{
return FALSE;
}
memcpy(block.ptr, u.ptr, block.len);
for (i = 1; i < iterations; i++)
{
if (!prf->get_bytes(prf, u, u.ptr))
{
return FALSE;
}
memxor(block.ptr, u.ptr, block.len);
}
return TRUE;
}
/**
* PBKDF2 key derivation function for PBES2, key must be allocated
*/
static bool pbkdf2(private_pkcs5_t *this, chunk_t password, chunk_t key)
{
prf_t *prf;
chunk_t keymat, block, seed;
size_t blocks;
u_int32_t i = 0;
prf = this->data.pbes2.prf;
if (!prf->set_key(prf, password))
{
return FALSE;
}
block.len = prf->get_block_size(prf);
blocks = (key.len - 1) / block.len + 1;
keymat = chunk_alloca(blocks * block.len);
seed = chunk_cata("cc", this->salt, chunk_from_thing(i));
for (; i < blocks; i++)
{
htoun32(seed.ptr + this->salt.len, i + 1);
block.ptr = keymat.ptr + (i * block.len);
if (!pbkdf2_f(block, prf, seed, this->iterations))
{
return FALSE;
}
}
memcpy(key.ptr, keymat.ptr, key.len);
return TRUE;
}
/**
* PBKDF1 key derivation function for PBES1, key must be allocated
*/
static bool pbkdf1(private_pkcs5_t *this, chunk_t password, chunk_t key)
{
hasher_t *hasher;
chunk_t hash;
u_int64_t i;
hasher = this->data.pbes1.hasher;
hash = chunk_alloca(hasher->get_hash_size(hasher));
if (!hasher->get_hash(hasher, password, NULL) ||
!hasher->get_hash(hasher, this->salt, hash.ptr))
{
return FALSE;
}
for (i = 1; i < this->iterations; i++)
{
if (!hasher->get_hash(hasher, hash, hash.ptr))
{
return FALSE;
}
}
memcpy(key.ptr, hash.ptr, key.len);
return TRUE;
}
static bool ensure_crypto_primitives(private_pkcs5_t *this, chunk_t data)
{
if (!this->crypter)
{
this->crypter = lib->crypto->create_crypter(lib->crypto, this->encr,
this->keylen);
if (!this->crypter)
{
DBG1(DBG_ASN, " %N encryption algorithm not available",
encryption_algorithm_names, this->encr);
return FALSE;
}
}
if (data.len % this->crypter->get_block_size(this->crypter))
{
DBG1(DBG_ASN, " data size is not a multiple of block size");
return FALSE;
}
switch (this->scheme)
{
case PKCS5_SCHEME_PBES1:
{
if (!this->data.pbes1.hasher)
{
hasher_t *hasher;
hasher = lib->crypto->create_hasher(lib->crypto,
this->data.pbes1.hash);
if (!hasher)
{
DBG1(DBG_ASN, " %N hash algorithm not available",
hash_algorithm_names, this->data.pbes1.hash);
return FALSE;
}
if (hasher->get_hash_size(hasher) < this->keylen)
{
hasher->destroy(hasher);
return FALSE;
}
this->data.pbes1.hasher = hasher;
}
}
case PKCS5_SCHEME_PBES2:
{
if (!this->data.pbes2.prf)
{
prf_t *prf;
prf = lib->crypto->create_prf(lib->crypto,
this->data.pbes2.prf_alg);
if (!prf)
{
DBG1(DBG_ASN, " %N prf algorithm not available",
pseudo_random_function_names,
this->data.pbes2.prf_alg);
return FALSE;
}
this->data.pbes2.prf = prf;
}
}
case PKCS5_SCHEME_PKCS12:
break;
}
return TRUE;
}
METHOD(pkcs5_t, decrypt, bool,
private_pkcs5_t *this, chunk_t password, chunk_t data, chunk_t *decrypted)
{
chunk_t keymat, key, iv;
kdf_t kdf;
if (!ensure_crypto_primitives(this, data) || !decrypted)
{
return FALSE;
}
kdf = pbkdf1;
switch (this->scheme)
{
case PKCS5_SCHEME_PKCS12:
kdf = pkcs12_kdf;
/* fall-through */
case PKCS5_SCHEME_PBES1:
keymat = chunk_alloca(this->keylen +
this->crypter->get_iv_size(this->crypter));
key = chunk_create(keymat.ptr, this->keylen);
iv = chunk_create(keymat.ptr + this->keylen,
keymat.len - this->keylen);
break;
case PKCS5_SCHEME_PBES2:
kdf = pbkdf2;
keymat = chunk_alloca(this->keylen);
key = keymat;
iv = this->data.pbes2.iv;
break;
default:
return FALSE;
}
return decrypt_generic(this, password, data, decrypted, kdf,
keymat, key, iv);
}
/**
* ASN.1 definition of a PBEParameter structure
*/
static const asn1Object_t pbeParameterObjects[] = {
{ 0, "PBEParameter", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
{ 1, "salt", ASN1_OCTET_STRING, ASN1_BODY }, /* 1 */
{ 1, "iterationCount", ASN1_INTEGER, ASN1_BODY }, /* 2 */
{ 0, "exit", ASN1_EOC, ASN1_EXIT }
};
#define PBEPARAM_SALT 1
#define PBEPARAM_ITERATION_COUNT 2
/**
* Parse a PBEParameter structure
*/
static bool parse_pbes1_params(private_pkcs5_t *this, chunk_t blob, int level0)
{
asn1_parser_t *parser;
chunk_t object;
int objectID;
bool success;
parser = asn1_parser_create(pbeParameterObjects, blob);
parser->set_top_level(parser, level0);
while (parser->iterate(parser, &objectID, &object))
{
switch (objectID)
{
case PBEPARAM_SALT:
{
this->salt = chunk_clone(object);
break;
}
case PBEPARAM_ITERATION_COUNT:
{
this->iterations = asn1_parse_integer_uint64(object);
break;
}
}
}
success = parser->success(parser);
parser->destroy(parser);
return success;
}
/**
* ASN.1 definition of a PBKDF2-params structure
* The salt is actually a CHOICE and could be an AlgorithmIdentifier from
* PBKDF2-SaltSources (but as per RFC 2898 that's for future versions).
*/
static const asn1Object_t pbkdf2ParamsObjects[] = {
{ 0, "PBKDF2-params", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
{ 1, "salt", ASN1_OCTET_STRING, ASN1_BODY }, /* 1 */
{ 1, "iterationCount",ASN1_INTEGER, ASN1_BODY }, /* 2 */
{ 1, "keyLength", ASN1_INTEGER, ASN1_OPT|ASN1_BODY }, /* 3 */
{ 1, "end opt", ASN1_EOC, ASN1_END }, /* 4 */
{ 1, "prf", ASN1_EOC, ASN1_DEF|ASN1_RAW }, /* 5 */
{ 0, "exit", ASN1_EOC, ASN1_EXIT }
};
#define PBKDF2_SALT 1
#define PBKDF2_ITERATION_COUNT 2
#define PBKDF2_KEYLENGTH 3
#define PBKDF2_PRF 5
/**
* Parse a PBKDF2-params structure
*/
static bool parse_pbkdf2_params(private_pkcs5_t *this, chunk_t blob, int level0)
{
asn1_parser_t *parser;
chunk_t object;
int objectID;
bool success;
parser = asn1_parser_create(pbkdf2ParamsObjects, blob);
parser->set_top_level(parser, level0);
/* keylen is optional */
this->keylen = 0;
while (parser->iterate(parser, &objectID, &object))
{
switch (objectID)
{
case PBKDF2_SALT:
{
this->salt = chunk_clone(object);
break;
}
case PBKDF2_ITERATION_COUNT:
{
this->iterations = asn1_parse_integer_uint64(object);
break;
}
case PBKDF2_KEYLENGTH:
{
this->keylen = (size_t)asn1_parse_integer_uint64(object);
break;
}
case PBKDF2_PRF:
{ /* defaults to id-hmacWithSHA1, no other is currently defined */
this->data.pbes2.prf_alg = PRF_HMAC_SHA1;
break;
}
}
}
success = parser->success(parser);
parser->destroy(parser);
return success;
}
/**
* ASN.1 definition of a PBES2-params structure
*/
static const asn1Object_t pbes2ParamsObjects[] = {
{ 0, "PBES2-params", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
{ 1, "keyDerivationFunc", ASN1_EOC, ASN1_RAW }, /* 1 */
{ 1, "encryptionScheme", ASN1_EOC, ASN1_RAW }, /* 2 */
{ 0, "exit", ASN1_EOC, ASN1_EXIT }
};
#define PBES2PARAMS_KEY_DERIVATION_FUNC 1
#define PBES2PARAMS_ENCRYPTION_SCHEME 2
/**
* Parse a PBES2-params structure
*/
static bool parse_pbes2_params(private_pkcs5_t *this, chunk_t blob, int level0)
{
asn1_parser_t *parser;
chunk_t object, params;
int objectID;
bool success = FALSE;
parser = asn1_parser_create(pbes2ParamsObjects, blob);
parser->set_top_level(parser, level0);
while (parser->iterate(parser, &objectID, &object))
{
switch (objectID)
{
case PBES2PARAMS_KEY_DERIVATION_FUNC:
{
int oid = asn1_parse_algorithmIdentifier(object,
parser->get_level(parser) + 1, &params);
if (oid != OID_PBKDF2)
{ /* unsupported key derivation function */
goto end;
}
if (!parse_pbkdf2_params(this, params,
parser->get_level(parser) + 1))
{
goto end;
}
break;
}
case PBES2PARAMS_ENCRYPTION_SCHEME:
{
int oid = asn1_parse_algorithmIdentifier(object,
parser->get_level(parser) + 1, &params);
if (oid != OID_3DES_EDE_CBC)
{ /* unsupported encryption scheme */
goto end;
}
if (this->keylen <= 0)
{ /* default key length for DES-EDE3-CBC-Pad */
this->keylen = 24;
}
if (!asn1_parse_simple_object(&params, ASN1_OCTET_STRING,
parser->get_level(parser) + 1, "IV"))
{
goto end;
}
this->encr = ENCR_3DES;
this->data.pbes2.iv = chunk_clone(params);
break;
}
}
}
success = parser->success(parser);
end:
parser->destroy(parser);
return success;
}
METHOD(pkcs5_t, destroy, void,
private_pkcs5_t *this)
{
DESTROY_IF(this->crypter);
chunk_free(&this->salt);
switch (this->scheme)
{
case PKCS5_SCHEME_PBES1:
DESTROY_IF(this->data.pbes1.hasher);
break;
case PKCS5_SCHEME_PBES2:
DESTROY_IF(this->data.pbes2.prf);
chunk_free(&this->data.pbes2.iv);
break;
case PKCS5_SCHEME_PKCS12:
break;
}
free(this);
}
/*
* Described in header
*/
pkcs5_t *pkcs5_from_algorithmIdentifier(chunk_t blob, int level0)
{
private_pkcs5_t *this;
chunk_t params;
int oid;
INIT(this,
.public = {
.decrypt = _decrypt,
.destroy = _destroy,
},
.scheme = PKCS5_SCHEME_PBES1,
.keylen = 8,
);
oid = asn1_parse_algorithmIdentifier(blob, level0, &params);
switch (oid)
{
case OID_PBE_MD5_DES_CBC:
this->encr = ENCR_DES;
this->data.pbes1.hash = HASH_MD5;
break;
case OID_PBE_SHA1_DES_CBC:
this->encr = ENCR_DES;
this->data.pbes1.hash = HASH_SHA1;
break;
case OID_PBE_SHA1_3DES_CBC:
this->scheme = PKCS5_SCHEME_PKCS12;
this->keylen = 24;
this->encr = ENCR_3DES;
this->data.pbes1.hash = HASH_SHA1;
break;
case OID_PBE_SHA1_RC2_CBC_40:
case OID_PBE_SHA1_RC2_CBC_128:
this->scheme = PKCS5_SCHEME_PKCS12;
this->keylen = (oid == OID_PBE_SHA1_RC2_CBC_40) ? 5 : 16;
this->encr = ENCR_RC2_CBC;
this->data.pbes1.hash = HASH_SHA1;
break;
case OID_PBES2:
this->scheme = PKCS5_SCHEME_PBES2;
break;
default:
/* encryption scheme not supported */
goto failure;
}
switch (this->scheme)
{
case PKCS5_SCHEME_PBES1:
case PKCS5_SCHEME_PKCS12:
if (!parse_pbes1_params(this, params, level0))
{
goto failure;
}
break;
case PKCS5_SCHEME_PBES2:
if (!parse_pbes2_params(this, params, level0))
{
goto failure;
}
break;
}
return &this->public;
failure:
destroy(this);
return NULL;
}
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