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/*
* 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/rsa_key_factory.h>
#include <new>
#include <keymaster/keymaster_context.h>
#include "openssl_err.h"
#include "openssl_utils.h"
#include "rsa_key.h"
#include "rsa_operation.h"
namespace keymaster {
const int kMaximumRsaKeySize = 16 * 1024; // 16kbits should be enough for anyone.
static RsaSigningOperationFactory sign_factory;
static RsaVerificationOperationFactory verify_factory;
static RsaEncryptionOperationFactory encrypt_factory;
static RsaDecryptionOperationFactory decrypt_factory;
OperationFactory* RsaKeyFactory::GetOperationFactory(keymaster_purpose_t purpose) const {
switch (purpose) {
case KM_PURPOSE_SIGN:
return &sign_factory;
case KM_PURPOSE_VERIFY:
return &verify_factory;
case KM_PURPOSE_ENCRYPT:
return &encrypt_factory;
case KM_PURPOSE_DECRYPT:
return &decrypt_factory;
default:
return nullptr;
}
}
keymaster_error_t RsaKeyFactory::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);
uint64_t public_exponent;
if (!authorizations.GetTagValue(TAG_RSA_PUBLIC_EXPONENT, &public_exponent)) {
LOG_E("%s", "No public exponent specified for RSA key generation");
return KM_ERROR_INVALID_ARGUMENT;
}
uint32_t key_size;
if (!authorizations.GetTagValue(TAG_KEY_SIZE, &key_size)) {
LOG_E("No key size specified for RSA key generation", 0);
return KM_ERROR_UNSUPPORTED_KEY_SIZE;
}
if (key_size % 8 != 0 || key_size > kMaximumRsaKeySize) {
LOG_E("Invalid key size of %u bits specified for RSA key generation", key_size);
return KM_ERROR_UNSUPPORTED_KEY_SIZE;
}
UniquePtr<BIGNUM, BIGNUM_Delete> exponent(BN_new());
UniquePtr<RSA, RsaKey::RSA_Delete> rsa_key(RSA_new());
UniquePtr<EVP_PKEY, EVP_PKEY_Delete> pkey(EVP_PKEY_new());
if (exponent.get() == NULL || rsa_key.get() == NULL || pkey.get() == NULL)
return KM_ERROR_MEMORY_ALLOCATION_FAILED;
if (!BN_set_word(exponent.get(), public_exponent) ||
!RSA_generate_key_ex(rsa_key.get(), key_size, exponent.get(), NULL /* callback */))
return TranslateLastOpenSslError();
if (EVP_PKEY_set1_RSA(pkey.get(), rsa_key.get()) != 1)
return TranslateLastOpenSslError();
KeymasterKeyBlob key_material;
keymaster_error_t 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 RsaKeyFactory::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;
uint64_t public_exponent;
uint32_t key_size;
keymaster_error_t error =
UpdateImportKeyDescription(key_description, input_key_material_format, input_key_material,
&authorizations, &public_exponent, &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 RsaKeyFactory::UpdateImportKeyDescription(const AuthorizationSet& key_description,
keymaster_key_format_t key_format,
const KeymasterKeyBlob& key_material,
AuthorizationSet* updated_description,
uint64_t* public_exponent,
uint32_t* key_size) const {
if (!updated_description || !public_exponent || !key_size)
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<RSA, RsaKey::RSA_Delete> rsa_key(EVP_PKEY_get1_RSA(pkey.get()));
if (!rsa_key.get())
return TranslateLastOpenSslError();
updated_description->Reinitialize(key_description);
*public_exponent = BN_get_word(rsa_key->e);
if (*public_exponent == 0xffffffffL)
return KM_ERROR_INVALID_KEY_BLOB;
if (!updated_description->GetTagValue(TAG_RSA_PUBLIC_EXPONENT, public_exponent))
updated_description->push_back(TAG_RSA_PUBLIC_EXPONENT, *public_exponent);
if (*public_exponent != BN_get_word(rsa_key->e)) {
LOG_E("Imported public exponent (%u) does not match specified public exponent (%u)",
*public_exponent, BN_get_word(rsa_key->e));
return KM_ERROR_IMPORT_PARAMETER_MISMATCH;
}
*key_size = RSA_size(rsa_key.get()) * 8;
if (!updated_description->GetTagValue(TAG_KEY_SIZE, key_size))
updated_description->push_back(TAG_KEY_SIZE, *key_size);
if (RSA_size(rsa_key.get()) * 8 != *key_size) {
LOG_E("Imported key size (%u bits) does not match specified key size (%u bits)",
RSA_size(rsa_key.get()) * 8, *key_size);
return KM_ERROR_IMPORT_PARAMETER_MISMATCH;
}
keymaster_algorithm_t algorithm = KM_ALGORITHM_RSA;
if (!updated_description->GetTagValue(TAG_ALGORITHM, &algorithm))
updated_description->push_back(TAG_ALGORITHM, KM_ALGORITHM_RSA);
if (algorithm != KM_ALGORITHM_RSA)
return KM_ERROR_IMPORT_PARAMETER_MISMATCH;
return KM_ERROR_OK;
}
keymaster_error_t RsaKeyFactory::CreateEmptyKey(const AuthorizationSet& hw_enforced,
const AuthorizationSet& sw_enforced,
UniquePtr<AsymmetricKey>* key) const {
keymaster_error_t error;
key->reset(new (std::nothrow) RsaKey(hw_enforced, sw_enforced, &error));
if (!key->get())
error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
return error;
}
} // namespace keymaster
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