/*
* 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 <keymaster/ec_key_factory.h>
#include <openssl/evp.h>
#include <keymaster/keymaster_context.h>
#include "ec_key.h"
#include "ecdsa_operation.h"
#include "openssl_err.h"
namespace keymaster {
static EcdsaSignOperationFactory sign_factory;
static EcdsaVerifyOperationFactory verify_factory;
OperationFactory* EcKeyFactory::GetOperationFactory(keymaster_purpose_t purpose) const {
switch (purpose) {
case KM_PURPOSE_SIGN:
return &sign_factory;
case KM_PURPOSE_VERIFY:
return &verify_factory;
default:
return nullptr;
}
}
/* static */
keymaster_error_t EcKeyFactory::GetCurveAndSize(const AuthorizationSet& key_description,
keymaster_ec_curve_t* curve,
uint32_t* key_size_bits) {
if (!key_description.GetTagValue(TAG_EC_CURVE, curve)) {
// Curve not specified. Fall back to deducing curve from key size.
if (!key_description.GetTagValue(TAG_KEY_SIZE, key_size_bits)) {
LOG_E("%s", "No curve or key size specified for EC key generation");
return KM_ERROR_UNSUPPORTED_KEY_SIZE;
}
keymaster_error_t error = EcKeySizeToCurve(*key_size_bits, curve);
if (error != KM_ERROR_OK) {
return KM_ERROR_UNSUPPORTED_KEY_SIZE;
}
} else {
keymaster_error_t error = EcCurveToKeySize(*curve, key_size_bits);
if (error != KM_ERROR_OK) {
return error;
}
uint32_t tag_key_size_bits;
if (key_description.GetTagValue(TAG_KEY_SIZE, &tag_key_size_bits) &&
*key_size_bits != tag_key_size_bits) {
LOG_E("Curve key size %d and specified key size %d don't match", key_size_bits,
tag_key_size_bits);
return KM_ERROR_INVALID_ARGUMENT;
}
}
return KM_ERROR_OK;
}
keymaster_error_t EcKeyFactory::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;
AuthorizationSet authorizations(key_description);
keymaster_ec_curve_t ec_curve;
uint32_t key_size;
keymaster_error_t error = GetCurveAndSize(authorizations, &ec_curve, &key_size);
if (error != KM_ERROR_OK) {
return error;
} else if (!authorizations.Contains(TAG_KEY_SIZE, key_size)) {
authorizations.push_back(TAG_KEY_SIZE, key_size);
} else if (!authorizations.Contains(TAG_EC_CURVE, ec_curve)) {
authorizations.push_back(TAG_EC_CURVE, ec_curve);
}
UniquePtr<EC_KEY, EC_KEY_Delete> ec_key(EC_KEY_new());
UniquePtr<EVP_PKEY, EVP_PKEY_Delete> pkey(EVP_PKEY_new());
if (ec_key.get() == NULL || pkey.get() == NULL)
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
UniquePtr<EC_GROUP, EC_GROUP_Delete> group(ChooseGroup(ec_curve));
if (group.get() == NULL) {
LOG_E("Unable to get EC group for curve %d", ec_curve);
return KM_ERROR_UNSUPPORTED_KEY_SIZE;
}
#if !defined(OPENSSL_IS_BORINGSSL)
EC_GROUP_set_point_conversion_form(group.get(), POINT_CONVERSION_UNCOMPRESSED);
EC_GROUP_set_asn1_flag(group.get(), OPENSSL_EC_NAMED_CURVE);
#endif
if (EC_KEY_set_group(ec_key.get(), group.get()) != 1 ||
EC_KEY_generate_key(ec_key.get()) != 1 || EC_KEY_check_key(ec_key.get()) < 0) {
return TranslateLastOpenSslError();
}
if (EVP_PKEY_set1_EC_KEY(pkey.get(), ec_key.get()) != 1)
return TranslateLastOpenSslError();
KeymasterKeyBlob key_material;
error = EvpKeyToKeyMaterial(pkey.get(), &key_material);
if (error != KM_ERROR_OK)
return error;
return context_->CreateKeyBlob(authorizations, KM_ORIGIN_GENERATED, key_material, key_blob,
hw_enforced, sw_enforced);
}
keymaster_error_t EcKeyFactory::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;
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;
return context_->CreateKeyBlob(authorizations, KM_ORIGIN_IMPORTED, input_key_material,
output_key_blob, hw_enforced, sw_enforced);
}
keymaster_error_t EcKeyFactory::UpdateImportKeyDescription(const AuthorizationSet& key_description,
keymaster_key_format_t key_format,
const KeymasterKeyBlob& key_material,
AuthorizationSet* updated_description,
uint32_t* key_size_bits) const {
if (!updated_description || !key_size_bits)
return KM_ERROR_OUTPUT_PARAMETER_NULL;
UniquePtr<EVP_PKEY, EVP_PKEY_Delete> pkey;
keymaster_error_t error =
KeyMaterialToEvpKey(key_format, key_material, keymaster_key_type(), &pkey);
if (error != KM_ERROR_OK)
return error;
UniquePtr<EC_KEY, EC_KEY_Delete> ec_key(EVP_PKEY_get1_EC_KEY(pkey.get()));
if (!ec_key.get())
return TranslateLastOpenSslError();
updated_description->Reinitialize(key_description);
size_t extracted_key_size_bits;
error = ec_get_group_size(EC_KEY_get0_group(ec_key.get()), &extracted_key_size_bits);
if (error != KM_ERROR_OK)
return error;
*key_size_bits = extracted_key_size_bits;
if (!updated_description->GetTagValue(TAG_KEY_SIZE, key_size_bits)) {
updated_description->push_back(TAG_KEY_SIZE, extracted_key_size_bits);
} else if (*key_size_bits != extracted_key_size_bits) {
return KM_ERROR_IMPORT_PARAMETER_MISMATCH;
}
keymaster_ec_curve_t curve_from_size;
error = EcKeySizeToCurve(*key_size_bits, &curve_from_size);
if (error != KM_ERROR_OK)
return error;
keymaster_ec_curve_t curve;
if (!updated_description->GetTagValue(TAG_EC_CURVE, &curve)) {
updated_description->push_back(TAG_EC_CURVE, curve_from_size);
} else if (curve_from_size != curve) {
return KM_ERROR_IMPORT_PARAMETER_MISMATCH;
}
keymaster_algorithm_t algorithm = KM_ALGORITHM_EC;
if (!updated_description->GetTagValue(TAG_ALGORITHM, &algorithm)) {
updated_description->push_back(TAG_ALGORITHM, KM_ALGORITHM_EC);
} else if (algorithm != KM_ALGORITHM_EC) {
return KM_ERROR_IMPORT_PARAMETER_MISMATCH;
}
return KM_ERROR_OK;
}
/* static */
EC_GROUP* EcKeyFactory::ChooseGroup(size_t key_size_bits) {
switch (key_size_bits) {
case 224:
return EC_GROUP_new_by_curve_name(NID_secp224r1);
break;
case 256:
return EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
break;
case 384:
return EC_GROUP_new_by_curve_name(NID_secp384r1);
break;
case 521:
return EC_GROUP_new_by_curve_name(NID_secp521r1);
break;
default:
return NULL;
break;
}
}
/* static */
EC_GROUP* EcKeyFactory::ChooseGroup(keymaster_ec_curve_t ec_curve) {
switch (ec_curve) {
case KM_EC_CURVE_P_224:
return EC_GROUP_new_by_curve_name(NID_secp224r1);
break;
case KM_EC_CURVE_P_256:
return EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
break;
case KM_EC_CURVE_P_384:
return EC_GROUP_new_by_curve_name(NID_secp384r1);
break;
case KM_EC_CURVE_P_521:
return EC_GROUP_new_by_curve_name(NID_secp521r1);
break;
default:
return nullptr;
break;
}
}
keymaster_error_t EcKeyFactory::CreateEmptyKey(const AuthorizationSet& hw_enforced,
const AuthorizationSet& sw_enforced,
UniquePtr<AsymmetricKey>* key) const {
keymaster_error_t error;
key->reset(new (std::nothrow) EcKey(hw_enforced, sw_enforced, &error));
if (!key->get())
error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
return error;
}
} // namespace keymaster