1 /*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <sys/types.h>
18 #include <unistd.h>
19
20 /**
21 * When a key is being migrated from a software keymaster implementation
22 * to a hardware keymaster implementation, the first 4 bytes of the key_blob
23 * given to the hardware implementation will be equal to SOFT_KEY_MAGIC.
24 * The hardware implementation should import these PKCS#8 format keys which
25 * are encoded like this:
26 *
27 * 4-byte SOFT_KEY_MAGIC
28 *
29 * 4-byte 32-bit integer big endian for public_key_length. This may be zero
30 * length which indicates the public key should be derived from the
31 * private key.
32 *
33 * public_key_length bytes of public key (may be empty)
34 *
35 * 4-byte 32-bit integer big endian for private_key_length
36 *
37 * private_key_length bytes of private key
38 */
39 static const uint8_t SOFT_KEY_MAGIC[] = { 'P', 'K', '#', '8' };
40
get_softkey_header_size()41 size_t get_softkey_header_size() {
42 return sizeof(SOFT_KEY_MAGIC);
43 }
44
add_softkey_header(uint8_t * key_blob,size_t key_blob_length)45 uint8_t* add_softkey_header(uint8_t* key_blob, size_t key_blob_length) {
46 if (key_blob_length < sizeof(SOFT_KEY_MAGIC)) {
47 return NULL;
48 }
49
50 memcpy(key_blob, SOFT_KEY_MAGIC, sizeof(SOFT_KEY_MAGIC));
51
52 return key_blob + sizeof(SOFT_KEY_MAGIC);
53 }
54
is_softkey(const uint8_t * key_blob,const size_t key_blob_length)55 bool is_softkey(const uint8_t* key_blob, const size_t key_blob_length) {
56 if (key_blob_length < sizeof(SOFT_KEY_MAGIC)) {
57 return false;
58 }
59
60 return !memcmp(key_blob, SOFT_KEY_MAGIC, sizeof(SOFT_KEY_MAGIC));
61 }
62