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Shawn Willden0d560bf2014-12-15 17:44:02 -07001/*
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 "hmac_operation.h"
18
19#include <openssl/evp.h>
20#include <openssl/hmac.h>
21
Shawn Willden567a4a02014-12-31 12:14:46 -070022#include "openssl_err.h"
Shawn Willden63ac0432014-12-29 14:07:08 -070023#include "symmetric_key.h"
24
Shawn Willdend79791b2015-05-09 12:48:36 +000025#if defined(OPENSSL_IS_BORINGSSL)
26typedef size_t openssl_size_t;
27#else
28typedef int openssl_size_t;
29#endif
30
Shawn Willden0d560bf2014-12-15 17:44:02 -070031namespace keymaster {
32
Shawn Willden63ac0432014-12-29 14:07:08 -070033/**
34 * Abstract base for HMAC operation factories. This class does all of the work to create
35 * HMAC operations.
36 */
37class HmacOperationFactory : public OperationFactory {
38 public:
39 virtual KeyType registry_key() const { return KeyType(KM_ALGORITHM_HMAC, purpose()); }
40
Shawn Willden3ed6d062015-04-15 13:39:38 -060041 virtual Operation* CreateOperation(const Key& key, const AuthorizationSet& begin_params,
42 keymaster_error_t* error);
Shawn Willden63ac0432014-12-29 14:07:08 -070043
44 virtual const keymaster_digest_t* SupportedDigests(size_t* digest_count) const;
45
46 virtual keymaster_purpose_t purpose() const = 0;
47};
48
Shawn Willden3ed6d062015-04-15 13:39:38 -060049Operation* HmacOperationFactory::CreateOperation(const Key& key,
Shawn Willden09f25272015-04-15 13:49:49 -060050 const AuthorizationSet& begin_params,
Shawn Willden3ed6d062015-04-15 13:39:38 -060051 keymaster_error_t* error) {
Shawn Willden09f25272015-04-15 13:49:49 -060052 uint32_t tag_length = 0;
53 begin_params.GetTagValue(TAG_MAC_LENGTH, &tag_length);
Shawn Willden0c60f6f2015-04-27 23:40:10 -060054 if (tag_length % 8 != 0) {
55 LOG_E("MAC length %d nod a multiple of 8 bits", tag_length);
56 *error = KM_ERROR_UNSUPPORTED_MAC_LENGTH;
57 return nullptr;
58 }
Shawn Willden63ac0432014-12-29 14:07:08 -070059
Shawn Willden226746b2015-05-08 11:36:56 -060060 keymaster_digest_t digest;
61 if (!begin_params.GetTagValue(TAG_DIGEST, &digest)) {
62 LOG_E("%d digests specified in begin params", begin_params.GetTagCount(TAG_DIGEST));
63 *error = KM_ERROR_UNSUPPORTED_DIGEST;
64 return nullptr;
65 } else if (!key.authorizations().Contains(TAG_DIGEST, digest)) {
66 LOG_E("Digest %d was specified, but not authorized by key", digest);
67 *error = KM_ERROR_INCOMPATIBLE_DIGEST;
68 return nullptr;
69 }
Shawn Willden63ac0432014-12-29 14:07:08 -070070
71 const SymmetricKey* symmetric_key = static_cast<const SymmetricKey*>(&key);
Shawn Willden0c60f6f2015-04-27 23:40:10 -060072 UniquePtr<HmacOperation> op(new HmacOperation(purpose(), symmetric_key->key_data(),
73 symmetric_key->key_data_size(), digest,
74 tag_length / 8));
Shawn Willden09f25272015-04-15 13:49:49 -060075 if (!op.get())
Shawn Willden63ac0432014-12-29 14:07:08 -070076 *error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
Shawn Willden09f25272015-04-15 13:49:49 -060077 else
78 *error = op->error();
79
80 if (*error != KM_ERROR_OK)
81 return nullptr;
82
83 return op.release();
Shawn Willden63ac0432014-12-29 14:07:08 -070084}
85
86static keymaster_digest_t supported_digests[] = {KM_DIGEST_SHA1, KM_DIGEST_SHA_2_224,
87 KM_DIGEST_SHA_2_256, KM_DIGEST_SHA_2_384,
88 KM_DIGEST_SHA_2_512};
89const keymaster_digest_t* HmacOperationFactory::SupportedDigests(size_t* digest_count) const {
90 *digest_count = array_length(supported_digests);
91 return supported_digests;
92}
93
94/**
95 * Concrete factory for creating HMAC signing operations.
96 */
97class HmacSignOperationFactory : public HmacOperationFactory {
98 keymaster_purpose_t purpose() const { return KM_PURPOSE_SIGN; }
99};
100static OperationFactoryRegistry::Registration<HmacSignOperationFactory> sign_registration;
101
102/**
103 * Concrete factory for creating HMAC verification operations.
104 */
105class HmacVerifyOperationFactory : public HmacOperationFactory {
106 keymaster_purpose_t purpose() const { return KM_PURPOSE_VERIFY; }
107};
108static OperationFactoryRegistry::Registration<HmacVerifyOperationFactory> verify_registration;
109
Shawn Willden567a4a02014-12-31 12:14:46 -0700110HmacOperation::HmacOperation(keymaster_purpose_t purpose, const uint8_t* key_data,
111 size_t key_data_size, keymaster_digest_t digest, size_t tag_length)
112 : Operation(purpose), error_(KM_ERROR_OK), tag_length_(tag_length) {
Shawn Willden0d560bf2014-12-15 17:44:02 -0700113 // Initialize CTX first, so dtor won't crash even if we error out later.
114 HMAC_CTX_init(&ctx_);
115
Shawn Willden09f25272015-04-15 13:49:49 -0600116 const EVP_MD* md = nullptr;
Shawn Willden0d560bf2014-12-15 17:44:02 -0700117 switch (digest) {
Shawn Willden09f25272015-04-15 13:49:49 -0600118 case KM_DIGEST_NONE:
119 case KM_DIGEST_MD5:
120 error_ = KM_ERROR_UNSUPPORTED_DIGEST;
121 break;
Shawn Willden51d5e0e2014-12-18 10:44:03 -0700122 case KM_DIGEST_SHA1:
123 md = EVP_sha1();
124 break;
Shawn Willden62c22862014-12-17 08:36:20 -0700125 case KM_DIGEST_SHA_2_224:
126 md = EVP_sha224();
127 break;
Shawn Willden0d560bf2014-12-15 17:44:02 -0700128 case KM_DIGEST_SHA_2_256:
129 md = EVP_sha256();
130 break;
Shawn Willden62c22862014-12-17 08:36:20 -0700131 case KM_DIGEST_SHA_2_384:
132 md = EVP_sha384();
133 break;
134 case KM_DIGEST_SHA_2_512:
135 md = EVP_sha512();
136 break;
Shawn Willden0d560bf2014-12-15 17:44:02 -0700137 }
138
Shawn Willden09f25272015-04-15 13:49:49 -0600139 if (md == nullptr) {
140 error_ = KM_ERROR_UNSUPPORTED_DIGEST;
Shawn Willden0d560bf2014-12-15 17:44:02 -0700141 return;
142 }
143
144 HMAC_Init_ex(&ctx_, key_data, key_data_size, md, NULL /* engine */);
145}
146
147HmacOperation::~HmacOperation() {
148 HMAC_CTX_cleanup(&ctx_);
149}
150
Shawn Willden111edb32015-02-05 22:44:24 -0700151keymaster_error_t HmacOperation::Begin(const AuthorizationSet& /* input_params */,
152 AuthorizationSet* /* output_params */) {
Shawn Willden0d560bf2014-12-15 17:44:02 -0700153 return error_;
154}
155
Shawn Willden6bfbff02015-02-06 19:48:24 -0700156keymaster_error_t HmacOperation::Update(const AuthorizationSet& /* additional_params */,
157 const Buffer& input, Buffer* /* output */,
Shawn Willden0d560bf2014-12-15 17:44:02 -0700158 size_t* input_consumed) {
159 if (!HMAC_Update(&ctx_, input.peek_read(), input.available_read()))
Shawn Willden567a4a02014-12-31 12:14:46 -0700160 return TranslateLastOpenSslError();
Shawn Willden0d560bf2014-12-15 17:44:02 -0700161 *input_consumed = input.available_read();
162 return KM_ERROR_OK;
163}
164
165keymaster_error_t HmacOperation::Abort() {
166 return KM_ERROR_OK;
167}
168
Shawn Willden6bfbff02015-02-06 19:48:24 -0700169keymaster_error_t HmacOperation::Finish(const AuthorizationSet& /* additional_params */,
170 const Buffer& signature, Buffer* output) {
Shawn Willden0d560bf2014-12-15 17:44:02 -0700171 uint8_t digest[EVP_MAX_MD_SIZE];
172 unsigned int digest_len;
173 if (!HMAC_Final(&ctx_, digest, &digest_len))
Shawn Willden567a4a02014-12-31 12:14:46 -0700174 return TranslateLastOpenSslError();
Shawn Willden0d560bf2014-12-15 17:44:02 -0700175
176 switch (purpose()) {
177 case KM_PURPOSE_SIGN:
Shawn Willden09f25272015-04-15 13:49:49 -0600178 if (tag_length_ > digest_len)
179 return KM_ERROR_UNSUPPORTED_MAC_LENGTH;
180 if (!output->reserve(tag_length_) || !output->write(digest, tag_length_))
181 return KM_ERROR_MEMORY_ALLOCATION_FAILED;
Shawn Willden0d560bf2014-12-15 17:44:02 -0700182 return KM_ERROR_OK;
183 case KM_PURPOSE_VERIFY:
Shawn Willden09f25272015-04-15 13:49:49 -0600184 if (signature.available_read() > digest_len)
Shawn Willden0d560bf2014-12-15 17:44:02 -0700185 return KM_ERROR_INVALID_INPUT_LENGTH;
Shawn Willden09f25272015-04-15 13:49:49 -0600186 if (CRYPTO_memcmp(signature.peek_read(), digest, signature.available_read()) != 0)
Shawn Willden0d560bf2014-12-15 17:44:02 -0700187 return KM_ERROR_VERIFICATION_FAILED;
188 return KM_ERROR_OK;
189 default:
190 return KM_ERROR_UNSUPPORTED_PURPOSE;
191 }
192}
193
194} // namespace keymaster