Refactor AesKey, extracting most functionality to SymmetricKey.
Symmetric key material handling is the same for all symmetric keys
(except, perhaps, DES if we want to handle parity bits correctly), so
move it into a common base.
Change-Id: I6ad5d35ce9020c1ae155bf0a8f2efe35674b1604
diff --git a/symmetric_key.cpp b/symmetric_key.cpp
new file mode 100644
index 0000000..5105c7d
--- /dev/null
+++ b/symmetric_key.cpp
@@ -0,0 +1,111 @@
+/*
+ * Copyright 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "symmetric_key.h"
+
+#include <assert.h>
+
+#include <openssl/err.h>
+#include <openssl/rand.h>
+
+#include "aes_key.h"
+#include "unencrypted_key_blob.h"
+
+namespace keymaster {
+
+/* static */
+SymmetricKey* SymmetricKey::GenerateKey(keymaster_algorithm_t algorithm,
+ const AuthorizationSet& key_description,
+ const Logger& logger, keymaster_error_t* error) {
+ if (!error)
+ return NULL;
+
+ *error = KM_ERROR_OK;
+
+ UniquePtr<SymmetricKey> key;
+ switch (algorithm) {
+ case KM_ALGORITHM_AES:
+ key.reset(new AesKey(key_description, logger));
+ break;
+ default:
+ *error = KM_ERROR_UNSUPPORTED_ALGORITHM;
+ return NULL;
+ };
+
+ uint32_t key_size_bits;
+ if (!key_description.GetTagValue(TAG_KEY_SIZE, &key_size_bits) || key_size_bits % 8 != 0) {
+ *error = KM_ERROR_UNSUPPORTED_KEY_SIZE;
+ return NULL;
+ }
+
+ key->key_data_size_ = key_size_bits / 8;
+ if (key->key_data_size_ > MAX_KEY_SIZE) {
+ *error = KM_ERROR_UNSUPPORTED_KEY_SIZE;
+ return NULL;
+ }
+ if (!RAND_bytes(key->key_data_, key->key_data_size_)) {
+ logger.error("Error %ul generating %d bit AES key", ERR_get_error(), key_size_bits);
+ *error = KM_ERROR_UNKNOWN_ERROR;
+ return NULL;
+ }
+
+ if (*error != KM_ERROR_OK)
+ return NULL;
+ return key.release();
+}
+
+/* static */
+SymmetricKey* SymmetricKey::CreateKey(keymaster_algorithm_t algorithm,
+ const UnencryptedKeyBlob& blob, const Logger& logger,
+ keymaster_error_t* error) {
+ switch (algorithm) {
+ case KM_ALGORITHM_AES:
+ return new AesKey(blob, logger, error);
+ default:
+ *error = KM_ERROR_UNSUPPORTED_ALGORITHM;
+ return NULL;
+ }
+}
+
+SymmetricKey::SymmetricKey(const UnencryptedKeyBlob& blob, const Logger& logger,
+ keymaster_error_t* error)
+ : Key(blob, logger), key_data_size_(blob.unencrypted_key_material_length()) {
+ if (error)
+ *error = LoadKey(blob);
+}
+
+SymmetricKey::~SymmetricKey() {
+ memset_s(key_data_, 0, MAX_KEY_SIZE);
+}
+
+keymaster_error_t SymmetricKey::LoadKey(const UnencryptedKeyBlob& blob) {
+ assert(blob.unencrypted_key_material_length() == key_data_size_);
+ memcpy(key_data_, blob.unencrypted_key_material(), key_data_size_);
+
+ return KM_ERROR_OK;
+}
+
+keymaster_error_t SymmetricKey::key_material(UniquePtr<uint8_t[]>* key_material,
+ size_t* size) const {
+ *size = key_data_size_;
+ key_material->reset(new uint8_t[*size]);
+ if (!key_material->get())
+ return KM_ERROR_MEMORY_ALLOCATION_FAILED;
+ memcpy(key_material->get(), key_data_, *size);
+ return KM_ERROR_OK;
+}
+
+} // namespace keymaster