1/*
2 * Copyright 2014 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 "aes_operation.h"
18
19namespace keymaster {
20
21static const keymaster_block_mode_t supported_block_modes[] = {KM_MODE_ECB, KM_MODE_CBC,
22                                                               KM_MODE_CTR, KM_MODE_GCM};
23
24const keymaster_block_mode_t*
25AesEvpCipherDescription::SupportedBlockModes(size_t* block_mode_count) const {
26    *block_mode_count = array_length(supported_block_modes);
27    return supported_block_modes;
28}
29
30const EVP_CIPHER* AesEvpCipherDescription::GetCipherInstance(size_t key_size,
31                                                             keymaster_block_mode_t block_mode,
32                                                             keymaster_error_t* error) const {
33    *error = KM_ERROR_OK;
34
35    switch (block_mode) {
36    case KM_MODE_ECB:
37        switch (key_size) {
38        case 16:
39            return EVP_aes_128_ecb();
40        case 24:
41            return EVP_aes_192_ecb();
42        case 32:
43            return EVP_aes_256_ecb();
44        };
45        *error = KM_ERROR_UNSUPPORTED_KEY_SIZE;
46        break;
47
48    case KM_MODE_CBC:
49        switch (key_size) {
50        case 16:
51            return EVP_aes_128_cbc();
52        case 24:
53            return EVP_aes_192_cbc();
54        case 32:
55            return EVP_aes_256_cbc();
56        };
57        *error = KM_ERROR_UNSUPPORTED_KEY_SIZE;
58        break;
59
60    case KM_MODE_CTR:
61        switch (key_size) {
62        case 16:
63            return EVP_aes_128_ctr();
64        case 24:
65            return EVP_aes_192_ctr();
66        case 32:
67            return EVP_aes_256_ctr();
68        }
69        *error = KM_ERROR_UNSUPPORTED_KEY_SIZE;
70        break;
71
72    case KM_MODE_GCM:
73        switch (key_size) {
74        case 16:
75            return EVP_aes_128_gcm();
76        case 24:
77            return EVP_aes_192_gcm();
78        case 32:
79            return EVP_aes_256_gcm();
80        }
81        *error = KM_ERROR_UNSUPPORTED_KEY_SIZE;
82        break;
83
84    default:
85        *error = KM_ERROR_UNSUPPORTED_BLOCK_MODE;
86        break;
87    }
88
89    assert(*error != KM_ERROR_OK);
90    return nullptr;
91}
92
93static AesEvpCipherDescription description;
94const EvpCipherDescription& AesOperationFactory::GetCipherDescription() const {
95    return description;
96}
97
98}  // namespace keymaster
99