ec_keymaster0_key.cpp

/*
 * Copyright 2015 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 "ec_keymaster0_key.h"

#include <memory>

#include <keymaster/android_keymaster_utils.h>
#include <keymaster/logger.h>
#include <keymaster/soft_keymaster_context.h>

#include "keymaster0_engine.h"
#include "openssl_utils.h"

using std::unique_ptr;

namespace keymaster {

EcdsaKeymaster0KeyFactory::EcdsaKeymaster0KeyFactory(const SoftKeymasterContext* context,
                                                     const Keymaster0Engine* engine)
    : EcKeyFactory(context), engine_(engine) {
}

keymaster_error_t EcdsaKeymaster0KeyFactory::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;

    if (!engine_ || !engine_->supports_ec())
        return super::GenerateKey(key_description, key_blob, hw_enforced, sw_enforced);

    uint32_t key_size;
    if (!key_description.GetTagValue(TAG_KEY_SIZE, &key_size)) {
        LOG_E("%s", "No key size specified for EC key generation");
        return KM_ERROR_UNSUPPORTED_KEY_SIZE;
    }

    KeymasterKeyBlob key_material;
    if (!engine_->GenerateEcKey(key_size, &key_material))
        return KM_ERROR_UNKNOWN_ERROR;

    // These tags are hardware-enforced.  Putting them in the hw_enforced set here will ensure that
    // context_->CreateKeyBlob doesn't put them in sw_enforced.
    hw_enforced->push_back(TAG_ALGORITHM, KM_ALGORITHM_EC);
    hw_enforced->push_back(TAG_KEY_SIZE, key_size);

    return context_->CreateKeyBlob(key_description, KM_ORIGIN_GENERATED, key_material, key_blob,
                                   hw_enforced, sw_enforced);
}

keymaster_error_t EcdsaKeymaster0KeyFactory::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;

    if (!engine_ || !engine_->supports_ec())
        return super::ImportKey(key_description, input_key_material_format, input_key_material,
                                output_key_blob, hw_enforced, sw_enforced);

    AuthorizationSet authorizations;
    uint32_t key_size;
    keymaster_error_t error = UpdateImportKeyDescription(
        key_description, input_key_material_format, input_key_material, &authorizations, &key_size);
    if (error != KM_ERROR_OK)
        return error;

    KeymasterKeyBlob imported_hw_key;
    if (!engine_->ImportKey(input_key_material_format, input_key_material, &imported_hw_key))
        return KM_ERROR_UNKNOWN_ERROR;

    // These tags are hardware-enforced.  Putting them in the hw_enforced set here will ensure that
    // context_->CreateKeyBlob doesn't put them in sw_enforced.
    hw_enforced->push_back(TAG_ALGORITHM, KM_ALGORITHM_EC);
    hw_enforced->push_back(TAG_KEY_SIZE, key_size);

    return context_->CreateKeyBlob(authorizations, KM_ORIGIN_IMPORTED, imported_hw_key,
                                   output_key_blob, hw_enforced, sw_enforced);
}

keymaster_error_t EcdsaKeymaster0KeyFactory::LoadKey(const KeymasterKeyBlob& key_material,
                                                     const AuthorizationSet& hw_enforced,
                                                     const AuthorizationSet& sw_enforced,
                                                     UniquePtr<Key>* key) const {
    if (!key)
        return KM_ERROR_OUTPUT_PARAMETER_NULL;

    if (sw_enforced.GetTagCount(TAG_ALGORITHM) == 1)
        return super::LoadKey(key_material, hw_enforced, sw_enforced, key);

    unique_ptr<EC_KEY, EC_Delete> ec_key(engine_->BlobToEcKey(key_material));
    if (!ec_key)
        return KM_ERROR_UNKNOWN_ERROR;

    keymaster_error_t error;
    key->reset(new EcKeymaster0Key(ec_key.release(), hw_enforced, sw_enforced, engine_, &error));
    if (error != KM_ERROR_OK)
        return error;

    return KM_ERROR_OK;
}

EcKeymaster0Key::EcKeymaster0Key(EC_KEY* ec_key, const AuthorizationSet& hw_enforced,
                                 const AuthorizationSet& sw_enforced,
                                 const Keymaster0Engine* engine, keymaster_error_t* error)
    : EcKey(ec_key, hw_enforced, sw_enforced, error), engine_(engine) {
}

keymaster_error_t EcKeymaster0Key::key_material(UniquePtr<uint8_t[]>* material,
                                                size_t* size) const {
    if (!engine_)
        return super::key_material(material, size);

    const keymaster_key_blob_t* blob = engine_->EcKeyToBlob(key());
    if (!blob)
        return KM_ERROR_UNKNOWN_ERROR;

    *size = blob->key_material_size;
    material->reset(new uint8_t[*size]);
    if (!material->get())
        return KM_ERROR_MEMORY_ALLOCATION_FAILED;
    memcpy(material->get(), blob->key_material, *size);
    return KM_ERROR_OK;
}

}  // namespace keymaster