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/*
* 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 <keymaster/android_keymaster_utils.h>
#include <keymaster/logger.h>
#include <keymaster/keymaster_context.h>
#include "aes_key.h"
#include "hmac_key.h"
#include "openssl_err.h"
namespace keymaster {
keymaster_error_t SymmetricKeyFactory::GenerateKey(const AuthorizationSet& key_description,
KeymasterKeyBlob* key_blob,
AuthorizationSet* hw_enforced,
AuthorizationSet* sw_enforced) const {
if (!key_blob || !hw_enforced || !sw_enforced)
return KM_ERROR_OUTPUT_PARAMETER_NULL;
uint32_t key_size_bits;
if (!key_description.GetTagValue(TAG_KEY_SIZE, &key_size_bits) ||
!key_size_supported(key_size_bits))
return KM_ERROR_UNSUPPORTED_KEY_SIZE;
keymaster_error_t error = validate_algorithm_specific_new_key_params(key_description);
if (error != KM_ERROR_OK)
return error;
size_t key_data_size = key_size_bits / 8;
KeymasterKeyBlob key_material(key_data_size);
if (!key_material.key_material)
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
error = context_->GenerateRandom(key_material.writable_data(), key_data_size);
if (error != KM_ERROR_OK) {
LOG_E("Error generating %d bit symmetric key", key_size_bits);
return error;
}
return context_->CreateKeyBlob(key_description, KM_ORIGIN_GENERATED, key_material, key_blob,
hw_enforced, sw_enforced);
}
keymaster_error_t SymmetricKeyFactory::ImportKey(const AuthorizationSet& key_description,
keymaster_key_format_t input_key_material_format,
const KeymasterKeyBlob& input_key_material,
KeymasterKeyBlob* output_key_blob,
AuthorizationSet* hw_enforced,
AuthorizationSet* sw_enforced) const {
if (!output_key_blob || !hw_enforced || !sw_enforced)
return KM_ERROR_OUTPUT_PARAMETER_NULL;
AuthorizationSet authorizations(key_description);
uint32_t key_size_bits;
if (!authorizations.GetTagValue(TAG_KEY_SIZE, &key_size_bits)) {
// Default key size if not specified.
key_size_bits = input_key_material.key_material_size * 8;
authorizations.push_back(TAG_KEY_SIZE, key_size_bits);
}
keymaster_error_t error = validate_algorithm_specific_new_key_params(key_description);
if (error != KM_ERROR_OK)
return error;
if (!key_size_supported(key_size_bits))
return KM_ERROR_UNSUPPORTED_KEY_SIZE;
if (input_key_material_format != KM_KEY_FORMAT_RAW)
return KM_ERROR_UNSUPPORTED_KEY_FORMAT;
if (key_size_bits != input_key_material.key_material_size * 8) {
LOG_E("Expected %d-bit key data but got %d bits", key_size_bits,
input_key_material.key_material_size * 8);
return KM_ERROR_INVALID_KEY_BLOB;
}
return context_->CreateKeyBlob(authorizations, KM_ORIGIN_IMPORTED, input_key_material,
output_key_blob, hw_enforced, sw_enforced);
}
static const keymaster_key_format_t supported_import_formats[] = {KM_KEY_FORMAT_RAW};
const keymaster_key_format_t*
SymmetricKeyFactory::SupportedImportFormats(size_t* format_count) const {
*format_count = array_length(supported_import_formats);
return supported_import_formats;
}
SymmetricKey::SymmetricKey(const KeymasterKeyBlob& key_material,
const AuthorizationSet& hw_enforced, const AuthorizationSet& sw_enforced,
keymaster_error_t* error)
: Key(hw_enforced, sw_enforced, error) {
if (*error != KM_ERROR_OK)
return;
uint8_t* tmp = dup_buffer(key_material.key_material, key_material.key_material_size);
if (tmp) {
key_data_.reset(tmp);
key_data_size_ = key_material.key_material_size;
*error = KM_ERROR_OK;
} else {
*error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
}
}
SymmetricKey::~SymmetricKey() {
memset_s(key_data_.get(), 0, key_data_size_);
}
keymaster_error_t SymmetricKey::key_material(UniquePtr<uint8_t[]>* key_material,
size_t* size) const {
*size = key_data_size_;
key_material->reset(new (std::nothrow) uint8_t[*size]);
if (!key_material->get())
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
memcpy(key_material->get(), key_data_.get(), *size);
return KM_ERROR_OK;
}
} // namespace keymaster
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