650 lines
15 KiB
C
650 lines
15 KiB
C
/*
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* Copyright (C) 2012 Tobias Brunner
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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 "pkcs8_builder.h"
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#include <debug.h>
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#include <asn1/oid.h>
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#include <asn1/asn1.h>
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#include <asn1/asn1_parser.h>
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#include <credentials/keys/private_key.h>
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/**
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* ASN.1 definition of a privateKeyInfo structure
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*/
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static const asn1Object_t pkinfoObjects[] = {
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{ 0, "privateKeyInfo", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
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{ 1, "version", ASN1_INTEGER, ASN1_BODY }, /* 1 */
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{ 1, "privateKeyAlgorithm", ASN1_EOC, ASN1_RAW }, /* 2 */
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{ 1, "privateKey", ASN1_OCTET_STRING, ASN1_BODY }, /* 3 */
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{ 1, "attributes", ASN1_CONTEXT_C_0, ASN1_OPT }, /* 4 */
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{ 1, "end opt", ASN1_EOC, ASN1_END }, /* 5 */
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{ 0, "exit", ASN1_EOC, ASN1_EXIT }
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};
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#define PKINFO_PRIVATE_KEY_ALGORITHM 2
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#define PKINFO_PRIVATE_KEY 3
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/**
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* Load a generic private key from an ASN.1 encoded blob
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*/
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static private_key_t *parse_private_key(chunk_t blob)
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{
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asn1_parser_t *parser;
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chunk_t object, params = chunk_empty;
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int objectID;
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private_key_t *key = NULL;
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key_type_t type = KEY_ANY;
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parser = asn1_parser_create(pkinfoObjects, blob);
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parser->set_flags(parser, FALSE, TRUE);
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while (parser->iterate(parser, &objectID, &object))
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{
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switch (objectID)
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{
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case PKINFO_PRIVATE_KEY_ALGORITHM:
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{
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int oid = asn1_parse_algorithmIdentifier(object,
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parser->get_level(parser) + 1, ¶ms);
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switch (oid)
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{
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case OID_RSA_ENCRYPTION:
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type = KEY_RSA;
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break;
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case OID_EC_PUBLICKEY:
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type = KEY_ECDSA;
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break;
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default:
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/* key type not supported */
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goto end;
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}
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break;
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}
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case PKINFO_PRIVATE_KEY:
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{
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DBG2(DBG_ASN, "-- > --");
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if (params.ptr)
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{
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key = lib->creds->create(lib->creds, CRED_PRIVATE_KEY,
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type, BUILD_BLOB_ALGID_PARAMS,
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params, BUILD_BLOB_ASN1_DER,
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object, BUILD_END);
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}
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else
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{
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key = lib->creds->create(lib->creds, CRED_PRIVATE_KEY,
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type, BUILD_BLOB_ASN1_DER, object,
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BUILD_END);
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}
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DBG2(DBG_ASN, "-- < --");
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break;
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}
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}
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}
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end:
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parser->destroy(parser);
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return key;
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}
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/**
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* Verify padding of decrypted blob.
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* Length of blob is adjusted accordingly.
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*/
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static bool verify_padding(chunk_t *blob)
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{
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u_int8_t padding, count;
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padding = count = blob->ptr[blob->len - 1];
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if (padding > 8)
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{
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return FALSE;
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}
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for (; blob->len && count; --blob->len, --count)
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{
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if (blob->ptr[blob->len - 1] != padding)
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{
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return FALSE;
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}
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}
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return TRUE;
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}
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/**
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* Prototype for key derivation functions.
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*/
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typedef bool (*kdf_t)(void *generator, chunk_t password, chunk_t salt,
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u_int64_t iterations, chunk_t key);
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/**
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* Try to decrypt the given blob with multiple passwords using the given
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* key derivation function. keymat is where the kdf function writes the key
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* to, key and iv point to the actual keys and initialization vectors resp.
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*/
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static private_key_t *decrypt_private_key(chunk_t blob,
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encryption_algorithm_t encr, size_t key_len, kdf_t kdf,
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void *generator, chunk_t salt, u_int64_t iterations,
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chunk_t keymat, chunk_t key, chunk_t iv)
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{
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enumerator_t *enumerator;
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shared_key_t *shared;
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crypter_t *crypter;
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private_key_t *private_key = NULL;
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crypter = lib->crypto->create_crypter(lib->crypto, encr, key_len);
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if (!crypter)
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{
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DBG1(DBG_ASN, " %N encryption algorithm not available",
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encryption_algorithm_names, encr);
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return NULL;
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}
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if (blob.len % crypter->get_block_size(crypter))
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{
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DBG1(DBG_ASN, " data size is not a multiple of block size");
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crypter->destroy(crypter);
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return NULL;
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}
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enumerator = lib->credmgr->create_shared_enumerator(lib->credmgr,
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SHARED_PRIVATE_KEY_PASS, NULL, NULL);
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while (enumerator->enumerate(enumerator, &shared, NULL, NULL))
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{
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chunk_t decrypted;
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if (!kdf(generator, shared->get_key(shared), salt, iterations, keymat))
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{
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continue;
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}
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crypter->set_key(crypter, key);
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crypter->decrypt(crypter, blob, iv, &decrypted);
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if (verify_padding(&decrypted))
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{
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private_key = parse_private_key(decrypted);
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if (private_key)
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{
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chunk_clear(&decrypted);
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break;
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}
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}
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chunk_free(&decrypted);
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}
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enumerator->destroy(enumerator);
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crypter->destroy(crypter);
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return private_key;
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}
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/**
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* Function F of PBKDF2
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*/
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static bool pbkdf2_f(chunk_t block, prf_t *prf, chunk_t seed,
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u_int64_t iterations)
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{
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chunk_t u;
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u_int64_t i;
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u = chunk_alloca(prf->get_block_size(prf));
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if (!prf->get_bytes(prf, seed, u.ptr))
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{
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return FALSE;
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}
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memcpy(block.ptr, u.ptr, block.len);
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for (i = 1; i < iterations; i++)
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{
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if (!prf->get_bytes(prf, u, u.ptr))
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{
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return FALSE;
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}
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memxor(block.ptr, u.ptr, block.len);
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}
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return TRUE;
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}
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/**
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* PBKDF2 key derivation function
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*/
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static bool pbkdf2(prf_t *prf, chunk_t password, chunk_t salt,
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u_int64_t iterations, chunk_t key)
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{
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chunk_t keymat, block, seed;
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size_t blocks;
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u_int32_t i = 0, *ni;
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prf->set_key(prf, password);
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block.len = prf->get_block_size(prf);
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blocks = (key.len - 1) / block.len + 1;
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keymat = chunk_alloca(blocks * block.len);
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seed = chunk_cata("cc", salt, chunk_from_thing(i));
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ni = (u_int32_t*)(seed.ptr + salt.len);
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for (; i < blocks; i++)
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{
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*ni = htonl(i + 1);
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block.ptr = keymat.ptr + (i * block.len);
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if (!pbkdf2_f(block, prf, seed, iterations))
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{
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return FALSE;
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}
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}
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memcpy(key.ptr, keymat.ptr, key.len);
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return TRUE;
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}
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/**
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* Decrypt an encrypted PKCS#8 encoded private key according to PBES2
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*/
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static private_key_t *decrypt_private_key_pbes2(chunk_t blob,
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encryption_algorithm_t encr, size_t key_len,
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chunk_t iv, pseudo_random_function_t prf_func,
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chunk_t salt, u_int64_t iterations)
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{
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private_key_t *private_key;
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prf_t *prf;
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chunk_t key;
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prf = lib->crypto->create_prf(lib->crypto, prf_func);
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if (!prf)
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{
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DBG1(DBG_ASN, " %N prf algorithm not available",
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pseudo_random_function_names, prf_func);
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return NULL;
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}
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key = chunk_alloca(key_len);
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private_key = decrypt_private_key(blob, encr, key_len, (kdf_t)pbkdf2, prf,
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salt, iterations, key, key, iv);
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prf->destroy(prf);
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return private_key;
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}
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/**
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* PBKDF1 key derivation function
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*/
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static bool pbkdf1(hasher_t *hasher, chunk_t password, chunk_t salt,
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u_int64_t iterations, chunk_t key)
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{
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chunk_t hash;
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u_int64_t i;
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hash = chunk_alloca(hasher->get_hash_size(hasher));
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hasher->get_hash(hasher, password, NULL);
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hasher->get_hash(hasher, salt, hash.ptr);
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for (i = 1; i < iterations; i++)
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{
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hasher->get_hash(hasher, hash, hash.ptr);
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}
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memcpy(key.ptr, hash.ptr, key.len);
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return TRUE;
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}
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/**
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* Decrypt an encrypted PKCS#8 encoded private key according to PBES1
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*/
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static private_key_t *decrypt_private_key_pbes1(chunk_t blob,
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encryption_algorithm_t encr, size_t key_len,
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hash_algorithm_t hash, chunk_t salt,
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u_int64_t iterations)
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{
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private_key_t *private_key = NULL;
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hasher_t *hasher = NULL;
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chunk_t keymat, key, iv;
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hasher = lib->crypto->create_hasher(lib->crypto, hash);
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if (!hasher)
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{
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DBG1(DBG_ASN, " %N hash algorithm not available",
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hash_algorithm_names, hash);
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goto end;
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}
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if (hasher->get_hash_size(hasher) < key_len)
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{
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goto end;
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}
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keymat = chunk_alloca(key_len * 2);
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key.len = key_len;
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key.ptr = keymat.ptr;
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iv.len = key_len;
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iv.ptr = keymat.ptr + key_len;
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private_key = decrypt_private_key(blob, encr, key_len, (kdf_t)pbkdf1,
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hasher, salt, iterations, keymat,
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key, iv);
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end:
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DESTROY_IF(hasher);
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return private_key;
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}
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/**
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* Parse an ASN1_INTEGER to a u_int64_t.
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*/
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static u_int64_t parse_asn1_integer_uint64(chunk_t blob)
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{
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u_int64_t val = 0;
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int i;
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for (i = 0; i < blob.len; i++)
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{ /* if it is longer than 8 bytes, we just use the 8 LSBs */
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val <<= 8;
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val |= (u_int64_t)blob.ptr[i];
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}
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return val;
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}
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/**
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* ASN.1 definition of a PBKDF2-params structure
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* The salt is actually a CHOICE and could be an AlgorithmIdentifier from
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* PBKDF2-SaltSources (but as per RFC 2898 that's for future versions).
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*/
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static const asn1Object_t pbkdf2ParamsObjects[] = {
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{ 0, "PBKDF2-params", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
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{ 1, "salt", ASN1_OCTET_STRING, ASN1_BODY }, /* 1 */
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{ 1, "iterationCount",ASN1_INTEGER, ASN1_BODY }, /* 2 */
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{ 1, "keyLength", ASN1_INTEGER, ASN1_OPT|ASN1_BODY }, /* 3 */
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{ 1, "end opt", ASN1_EOC, ASN1_END }, /* 4 */
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{ 1, "prf", ASN1_EOC, ASN1_DEF|ASN1_RAW }, /* 5 */
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{ 0, "exit", ASN1_EOC, ASN1_EXIT }
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};
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#define PBKDF2_SALT 1
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#define PBKDF2_ITERATION_COUNT 2
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#define PBKDF2_KEY_LENGTH 3
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#define PBKDF2_PRF 5
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/**
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* Parse a PBKDF2-params structure
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*/
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static void parse_pbkdf2_params(chunk_t blob, chunk_t *salt,
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u_int64_t *iterations, size_t *key_len,
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pseudo_random_function_t *prf)
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{
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asn1_parser_t *parser;
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chunk_t object;
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int objectID;
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parser = asn1_parser_create(pbkdf2ParamsObjects, blob);
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*key_len = 0; /* key_len is optional */
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while (parser->iterate(parser, &objectID, &object))
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{
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switch (objectID)
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{
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case PBKDF2_SALT:
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{
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*salt = object;
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break;
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}
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case PBKDF2_ITERATION_COUNT:
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{
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*iterations = parse_asn1_integer_uint64(object);
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break;
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}
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case PBKDF2_KEY_LENGTH:
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{
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*key_len = (size_t)parse_asn1_integer_uint64(object);
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break;
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}
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case PBKDF2_PRF:
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{ /* defaults to id-hmacWithSHA1 */
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*prf = PRF_HMAC_SHA1;
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break;
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}
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}
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}
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parser->destroy(parser);
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}
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/**
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* ASN.1 definition of a PBES2-params structure
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*/
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static const asn1Object_t pbes2ParamsObjects[] = {
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{ 0, "PBES2-params", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
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{ 1, "keyDerivationFunc", ASN1_EOC, ASN1_RAW }, /* 1 */
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{ 1, "encryptionScheme", ASN1_EOC, ASN1_RAW }, /* 2 */
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{ 0, "exit", ASN1_EOC, ASN1_EXIT }
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};
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#define PBES2PARAMS_KEY_DERIVATION_FUNC 1
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#define PBES2PARAMS_ENCRYPTION_SCHEME 2
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/**
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* Parse a PBES2-params structure
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*/
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static void parse_pbes2_params(chunk_t blob, chunk_t *salt,
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u_int64_t *iterations, size_t *key_len,
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pseudo_random_function_t *prf,
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encryption_algorithm_t *encr, chunk_t *iv)
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{
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asn1_parser_t *parser;
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chunk_t object, params;
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int objectID;
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parser = asn1_parser_create(pbes2ParamsObjects, blob);
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while (parser->iterate(parser, &objectID, &object))
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{
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switch (objectID)
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{
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case PBES2PARAMS_KEY_DERIVATION_FUNC:
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{
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int oid = asn1_parse_algorithmIdentifier(object,
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parser->get_level(parser) + 1, ¶ms);
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if (oid != OID_PBKDF2)
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{ /* unsupported key derivation function */
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goto end;
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}
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parse_pbkdf2_params(params, salt, iterations, key_len, prf);
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break;
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}
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case PBES2PARAMS_ENCRYPTION_SCHEME:
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{
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int oid = asn1_parse_algorithmIdentifier(object,
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parser->get_level(parser) + 1, ¶ms);
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if (oid != OID_3DES_EDE_CBC)
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{ /* unsupported encryption scheme */
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goto end;
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}
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if (*key_len <= 0)
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{ /* default key len for DES-EDE3-CBC-Pad */
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*key_len = 24;
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}
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if (!asn1_parse_simple_object(¶ms, ASN1_OCTET_STRING,
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parser->get_level(parser) + 1, "IV"))
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{
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goto end;
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}
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*encr = ENCR_3DES;
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*iv = params;
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break;
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}
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}
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}
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end:
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parser->destroy(parser);
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}
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/**
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* ASN.1 definition of a PBEParameter structure
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*/
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static const asn1Object_t pbeParameterObjects[] = {
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{ 0, "PBEParameter", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
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{ 1, "salt", ASN1_OCTET_STRING, ASN1_BODY }, /* 1 */
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{ 1, "iterationCount", ASN1_INTEGER, ASN1_BODY }, /* 2 */
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{ 0, "exit", ASN1_EOC, ASN1_EXIT }
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};
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#define PBEPARAM_SALT 1
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#define PBEPARAM_ITERATION_COUNT 2
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/**
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* Parse a PBEParameter structure
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*/
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static void parse_pbe_parameters(chunk_t blob, chunk_t *salt,
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u_int64_t *iterations)
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{
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asn1_parser_t *parser;
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chunk_t object;
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int objectID;
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parser = asn1_parser_create(pbeParameterObjects, blob);
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while (parser->iterate(parser, &objectID, &object))
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{
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switch (objectID)
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{
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case PBEPARAM_SALT:
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{
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*salt = object;
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|
break;
|
|
}
|
|
case PBEPARAM_ITERATION_COUNT:
|
|
{
|
|
*iterations = parse_asn1_integer_uint64(object);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
parser->destroy(parser);
|
|
}
|
|
|
|
/**
|
|
* ASN.1 definition of an encryptedPrivateKeyInfo structure
|
|
*/
|
|
static const asn1Object_t encryptedPKIObjects[] = {
|
|
{ 0, "encryptedPrivateKeyInfo", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
|
|
{ 1, "encryptionAlgorithm", ASN1_EOC, ASN1_RAW }, /* 1 */
|
|
{ 1, "encryptedData", ASN1_OCTET_STRING, ASN1_BODY }, /* 2 */
|
|
{ 0, "exit", ASN1_EOC, ASN1_EXIT }
|
|
};
|
|
#define EPKINFO_ENCRYPTION_ALGORITHM 1
|
|
#define EPKINFO_ENCRYPTED_DATA 2
|
|
|
|
/**
|
|
* Load an encrypted private key from an ASN.1 encoded blob
|
|
* Schemes per PKCS#5 (RFC 2898)
|
|
*/
|
|
static private_key_t *parse_encrypted_private_key(chunk_t blob)
|
|
{
|
|
asn1_parser_t *parser;
|
|
chunk_t object, params, salt = chunk_empty, iv = chunk_empty;
|
|
u_int64_t iterations = 0;
|
|
int objectID;
|
|
encryption_algorithm_t encr = ENCR_UNDEFINED;
|
|
hash_algorithm_t hash = HASH_UNKNOWN;
|
|
pseudo_random_function_t prf = PRF_UNDEFINED;
|
|
private_key_t *key = NULL;
|
|
size_t key_len = 8;
|
|
|
|
parser = asn1_parser_create(encryptedPKIObjects, blob);
|
|
|
|
while (parser->iterate(parser, &objectID, &object))
|
|
{
|
|
switch (objectID)
|
|
{
|
|
case EPKINFO_ENCRYPTION_ALGORITHM:
|
|
{
|
|
int oid = asn1_parse_algorithmIdentifier(object,
|
|
parser->get_level(parser) + 1, ¶ms);
|
|
|
|
switch (oid)
|
|
{
|
|
case OID_PBE_MD5_DES_CBC:
|
|
encr = ENCR_DES;
|
|
hash = HASH_MD5;
|
|
parse_pbe_parameters(params, &salt, &iterations);
|
|
break;
|
|
case OID_PBE_SHA1_DES_CBC:
|
|
encr = ENCR_DES;
|
|
hash = HASH_SHA1;
|
|
parse_pbe_parameters(params, &salt, &iterations);
|
|
break;
|
|
case OID_PBES2:
|
|
parse_pbes2_params(params, &salt, &iterations,
|
|
&key_len, &prf, &encr, &iv);
|
|
break;
|
|
default:
|
|
/* encryption scheme not supported */
|
|
goto end;
|
|
}
|
|
break;
|
|
}
|
|
case EPKINFO_ENCRYPTED_DATA:
|
|
{
|
|
if (prf != PRF_UNDEFINED)
|
|
{
|
|
key = decrypt_private_key_pbes2(object, encr, key_len, iv,
|
|
prf, salt, iterations);
|
|
}
|
|
else
|
|
{
|
|
key = decrypt_private_key_pbes1(object, encr, key_len, hash,
|
|
salt, iterations);
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
end:
|
|
parser->destroy(parser);
|
|
return key;
|
|
}
|
|
|
|
/**
|
|
* See header.
|
|
*/
|
|
private_key_t *pkcs8_private_key_load(key_type_t type, va_list args)
|
|
{
|
|
chunk_t blob = chunk_empty;
|
|
private_key_t *key;
|
|
|
|
while (TRUE)
|
|
{
|
|
switch (va_arg(args, builder_part_t))
|
|
{
|
|
case BUILD_BLOB_ASN1_DER:
|
|
blob = va_arg(args, chunk_t);
|
|
continue;
|
|
case BUILD_END:
|
|
break;
|
|
default:
|
|
return NULL;
|
|
}
|
|
break;
|
|
}
|
|
/* we don't know whether it is encrypted or not, try both ways */
|
|
key = parse_encrypted_private_key(blob);
|
|
if (!key)
|
|
{
|
|
key = parse_private_key(blob);
|
|
}
|
|
return key;
|
|
}
|
|
|