| /* |
| * 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 <stdio.h> |
| |
| #include <UniquePtr.h> |
| |
| #include <openssl/aes.h> |
| #include <openssl/err.h> |
| #include <openssl/rand.h> |
| |
| #include <keymaster/logger.h> |
| |
| #include "aes_key.h" |
| #include "aes_operation.h" |
| #include "openssl_err.h" |
| |
| namespace keymaster { |
| |
| static const size_t GCM_NONCE_SIZE = 12; |
| static const size_t GCM_MAX_TAG_LENGTH = 16; |
| static const size_t GCM_MIN_TAG_LENGTH = 12; |
| |
| Operation* AesOperationFactory::CreateOperation(const Key& key, |
| const AuthorizationSet& begin_params, |
| keymaster_error_t* error) { |
| *error = KM_ERROR_OK; |
| const SymmetricKey* symmetric_key = static_cast<const SymmetricKey*>(&key); |
| |
| switch (symmetric_key->key_data_size()) { |
| case 16: |
| case 24: |
| case 32: |
| break; |
| default: |
| *error = KM_ERROR_UNSUPPORTED_KEY_SIZE; |
| return nullptr; |
| } |
| |
| keymaster_block_mode_t block_mode; |
| if (!begin_params.GetTagValue(TAG_BLOCK_MODE, &block_mode)) { |
| LOG_E("%d block modes specified in begin params", begin_params.GetTagCount(TAG_BLOCK_MODE)); |
| *error = KM_ERROR_UNSUPPORTED_BLOCK_MODE; |
| } else if (!supported(block_mode)) { |
| LOG_E("Block mode %d not supported", block_mode); |
| *error = KM_ERROR_UNSUPPORTED_BLOCK_MODE; |
| } else if (!key.authorizations().Contains(TAG_BLOCK_MODE, block_mode)) { |
| LOG_E("Block mode %d was specified, but not authorized by key", block_mode); |
| *error = KM_ERROR_INCOMPATIBLE_BLOCK_MODE; |
| } |
| |
| size_t tag_length = 0; |
| if (block_mode == KM_MODE_GCM && purpose() == KM_PURPOSE_ENCRYPT) { |
| uint32_t tag_length_bits; |
| if (!begin_params.GetTagValue(TAG_MAC_LENGTH, &tag_length_bits)) |
| *error = KM_ERROR_MISSING_MAC_LENGTH; |
| tag_length = tag_length_bits / 8; |
| if (tag_length_bits % 8 != 0 || tag_length > GCM_MAX_TAG_LENGTH || |
| tag_length < GCM_MIN_TAG_LENGTH) |
| *error = KM_ERROR_UNSUPPORTED_MAC_LENGTH; |
| } |
| |
| keymaster_padding_t padding; |
| if (!begin_params.GetTagValue(TAG_PADDING, &padding)) { |
| LOG_E("%d padding modes specified in begin params", begin_params.GetTagCount(TAG_PADDING)); |
| *error = KM_ERROR_UNSUPPORTED_PADDING_MODE; |
| } else if (!supported(padding)) { |
| LOG_E("Padding mode %d not supported", padding); |
| *error = KM_ERROR_UNSUPPORTED_PADDING_MODE; |
| } else if (block_mode == KM_MODE_CTR && padding != KM_PAD_NONE) { |
| LOG_E("CTR mode does not support padding", 0); |
| *error = KM_ERROR_INCOMPATIBLE_PADDING_MODE; |
| } else if (!key.authorizations().Contains(TAG_PADDING, padding)) { |
| LOG_E("Padding mode %d was specified, but not authorized by key", padding); |
| *error = KM_ERROR_INCOMPATIBLE_PADDING_MODE; |
| } |
| |
| bool caller_nonce = key.authorizations().GetTagValue(TAG_CALLER_NONCE); |
| |
| if (*error != KM_ERROR_OK) |
| return nullptr; |
| |
| return CreateEvpOperation(*symmetric_key, block_mode, padding, caller_nonce, tag_length, error); |
| } |
| |
| Operation* AesOperationFactory::CreateEvpOperation(const SymmetricKey& key, |
| keymaster_block_mode_t block_mode, |
| keymaster_padding_t padding, bool caller_iv, |
| size_t tag_length, keymaster_error_t* error) { |
| Operation* op = NULL; |
| switch (purpose()) { |
| case KM_PURPOSE_ENCRYPT: |
| op = new AesEvpEncryptOperation(block_mode, padding, caller_iv, tag_length, key.key_data(), |
| key.key_data_size()); |
| break; |
| case KM_PURPOSE_DECRYPT: |
| op = new AesEvpDecryptOperation(block_mode, padding, key.key_data(), key.key_data_size()); |
| break; |
| default: |
| *error = KM_ERROR_UNSUPPORTED_PURPOSE; |
| return NULL; |
| } |
| |
| if (!op) |
| *error = KM_ERROR_MEMORY_ALLOCATION_FAILED; |
| return op; |
| } |
| |
| static const keymaster_block_mode_t supported_block_modes[] = {KM_MODE_ECB, KM_MODE_CBC, |
| KM_MODE_CTR, KM_MODE_GCM}; |
| |
| const keymaster_block_mode_t* |
| AesOperationFactory::SupportedBlockModes(size_t* block_mode_count) const { |
| *block_mode_count = array_length(supported_block_modes); |
| return supported_block_modes; |
| } |
| |
| static const keymaster_padding_t supported_padding_modes[] = {KM_PAD_NONE, KM_PAD_PKCS7}; |
| const keymaster_padding_t* |
| AesOperationFactory::SupportedPaddingModes(size_t* padding_mode_count) const { |
| *padding_mode_count = array_length(supported_padding_modes); |
| return supported_padding_modes; |
| } |
| |
| AesEvpOperation::AesEvpOperation(keymaster_purpose_t purpose, keymaster_block_mode_t block_mode, |
| keymaster_padding_t padding, bool caller_iv, const uint8_t* key, |
| size_t key_size) |
| : Operation(purpose), block_mode_(block_mode), caller_iv_(caller_iv), aad_provided_(false), |
| key_size_(key_size), padding_(padding) { |
| memcpy(key_, key, key_size_); |
| EVP_CIPHER_CTX_init(&ctx_); |
| } |
| |
| AesEvpOperation::~AesEvpOperation() { |
| EVP_CIPHER_CTX_cleanup(&ctx_); |
| } |
| |
| keymaster_error_t AesEvpOperation::InitializeCipher() { |
| const EVP_CIPHER* cipher; |
| switch (block_mode_) { |
| case KM_MODE_ECB: |
| switch (key_size_) { |
| case 16: |
| cipher = EVP_aes_128_ecb(); |
| break; |
| case 24: |
| cipher = EVP_aes_192_ecb(); |
| break; |
| case 32: |
| cipher = EVP_aes_256_ecb(); |
| break; |
| default: |
| return KM_ERROR_UNSUPPORTED_KEY_SIZE; |
| } |
| break; |
| case KM_MODE_CBC: |
| switch (key_size_) { |
| case 16: |
| cipher = EVP_aes_128_cbc(); |
| break; |
| case 24: |
| cipher = EVP_aes_192_cbc(); |
| break; |
| case 32: |
| cipher = EVP_aes_256_cbc(); |
| break; |
| default: |
| return KM_ERROR_UNSUPPORTED_KEY_SIZE; |
| } |
| break; |
| case KM_MODE_CTR: |
| switch (key_size_) { |
| case 16: |
| cipher = EVP_aes_128_ctr(); |
| break; |
| case 24: |
| cipher = EVP_aes_192_ctr(); |
| break; |
| case 32: |
| cipher = EVP_aes_256_ctr(); |
| break; |
| default: |
| return KM_ERROR_UNSUPPORTED_KEY_SIZE; |
| } |
| break; |
| case KM_MODE_GCM: |
| switch (key_size_) { |
| case 16: |
| cipher = EVP_aes_128_gcm(); |
| break; |
| case 24: |
| cipher = EVP_aes_192_gcm(); |
| break; |
| case 32: |
| cipher = EVP_aes_256_gcm(); |
| break; |
| default: |
| return KM_ERROR_UNSUPPORTED_KEY_SIZE; |
| } |
| break; |
| default: |
| return KM_ERROR_UNSUPPORTED_BLOCK_MODE; |
| } |
| |
| if (!EVP_CipherInit_ex(&ctx_, cipher, NULL /* engine */, key_, iv_.get(), evp_encrypt_mode())) |
| return TranslateLastOpenSslError(); |
| |
| switch (padding_) { |
| case KM_PAD_NONE: |
| EVP_CIPHER_CTX_set_padding(&ctx_, 0 /* disable padding */); |
| break; |
| case KM_PAD_PKCS7: |
| // This is the default for OpenSSL EVP cipher operations. |
| break; |
| default: |
| return KM_ERROR_UNSUPPORTED_PADDING_MODE; |
| } |
| |
| return KM_ERROR_OK; |
| } |
| |
| bool AesEvpOperation::need_iv() const { |
| switch (block_mode_) { |
| case KM_MODE_CBC: |
| case KM_MODE_CTR: |
| case KM_MODE_GCM: |
| return true; |
| case KM_MODE_ECB: |
| return false; |
| default: |
| // Shouldn't get here. |
| assert(false); |
| return false; |
| } |
| } |
| |
| keymaster_error_t AesEvpDecryptOperation::Begin(const AuthorizationSet& input_params, |
| AuthorizationSet* output_params) { |
| if (!output_params) |
| return KM_ERROR_OUTPUT_PARAMETER_NULL; |
| |
| if (need_iv()) { |
| keymaster_error_t error = GetIv(input_params); |
| if (error != KM_ERROR_OK) |
| return error; |
| } |
| |
| return InitializeCipher(); |
| } |
| |
| keymaster_error_t AesEvpEncryptOperation::Begin(const AuthorizationSet& input_params, |
| AuthorizationSet* output_params) { |
| if (!output_params) |
| return KM_ERROR_OUTPUT_PARAMETER_NULL; |
| |
| if (need_iv()) { |
| keymaster_error_t error = KM_ERROR_OK; |
| if (input_params.find(TAG_NONCE) == -1) |
| error = GenerateIv(); |
| else if (caller_iv_) |
| error = GetIv(input_params); |
| else |
| error = KM_ERROR_CALLER_NONCE_PROHIBITED; |
| |
| if (error == KM_ERROR_OK) |
| output_params->push_back(TAG_NONCE, iv_.get(), iv_length_); |
| else |
| return error; |
| } |
| |
| return InitializeCipher(); |
| } |
| |
| keymaster_error_t AesEvpOperation::GetIv(const AuthorizationSet& input_params) { |
| keymaster_blob_t iv_blob; |
| if (!input_params.GetTagValue(TAG_NONCE, &iv_blob)) { |
| LOG_E("No IV provided", 0); |
| return KM_ERROR_INVALID_ARGUMENT; |
| } |
| if (block_mode_ == KM_MODE_GCM) { |
| if (iv_blob.data_length != GCM_NONCE_SIZE) { |
| LOG_E("Expected %d-byte nonce for AES-GCM operation, but got %d bytes", GCM_NONCE_SIZE, |
| iv_blob.data_length); |
| return KM_ERROR_INVALID_NONCE; |
| } |
| } else if (iv_blob.data_length != AES_BLOCK_SIZE) { |
| LOG_E("Expected %d-byte IV for AES operation, but got %d bytes", AES_BLOCK_SIZE, |
| iv_blob.data_length); |
| return KM_ERROR_INVALID_NONCE; |
| } |
| iv_.reset(dup_array(iv_blob.data, iv_blob.data_length)); |
| if (!iv_.get()) |
| return KM_ERROR_MEMORY_ALLOCATION_FAILED; |
| iv_length_ = iv_blob.data_length; |
| return KM_ERROR_OK; |
| } |
| |
| keymaster_error_t AesEvpEncryptOperation::GenerateIv() { |
| iv_length_ = (block_mode_ == KM_MODE_GCM) ? GCM_NONCE_SIZE : AES_BLOCK_SIZE; |
| iv_.reset(new uint8_t[iv_length_]); |
| if (!iv_.get()) |
| return KM_ERROR_MEMORY_ALLOCATION_FAILED; |
| if (RAND_bytes(iv_.get(), iv_length_) != 1) |
| return TranslateLastOpenSslError(); |
| return KM_ERROR_OK; |
| } |
| |
| inline size_t min(size_t a, size_t b) { |
| if (a < b) |
| return a; |
| return b; |
| } |
| |
| keymaster_error_t AesEvpOperation::Update(const AuthorizationSet& additional_params, |
| const Buffer& input, |
| AuthorizationSet* /* output_params */, Buffer* output, |
| size_t* input_consumed) { |
| if (!aad_provided_ && block_mode_ == KM_MODE_GCM) { |
| keymaster_blob_t aad; |
| if (additional_params.GetTagValue(TAG_ASSOCIATED_DATA, &aad)) { |
| // Incantation to add AAD is to call update with null output. Ugly. |
| int output_written; |
| if (!EVP_CipherUpdate(&ctx_, nullptr /* out */, &output_written, aad.data, |
| aad.data_length)) |
| return TranslateLastOpenSslError(); |
| } |
| aad_provided_ = true; |
| } |
| |
| output->reserve(input.available_read() + AES_BLOCK_SIZE); |
| |
| const uint8_t* input_pos = input.peek_read(); |
| const uint8_t* input_end = input_pos + input.available_read(); |
| |
| int output_written = -1; |
| if (!EVP_CipherUpdate(&ctx_, output->peek_write(), &output_written, input_pos, |
| input_end - input_pos)) |
| return TranslateLastOpenSslError(); |
| |
| assert(output_written >= 0); |
| assert(output_written <= (int)output->available_write()); |
| output->advance_write(output_written); |
| *input_consumed = input.available_read(); |
| return KM_ERROR_OK; |
| } |
| |
| keymaster_error_t AesEvpDecryptOperation::Update(const AuthorizationSet& additional_params, |
| const Buffer& input, |
| AuthorizationSet* output_params, Buffer* output, |
| size_t* input_consumed) { |
| if (!tag_provided_ && block_mode_ == KM_MODE_GCM && purpose() == KM_PURPOSE_DECRYPT) { |
| keymaster_blob_t tag; |
| if (additional_params.GetTagValue(TAG_AEAD_TAG, &tag)) { |
| if (tag.data_length < GCM_MIN_TAG_LENGTH || tag.data_length > GCM_MAX_TAG_LENGTH) |
| return KM_ERROR_UNSUPPORTED_MAC_LENGTH; |
| |
| if (!EVP_CIPHER_CTX_ctrl(&ctx_, EVP_CTRL_GCM_SET_TAG, tag.data_length, |
| const_cast<uint8_t*>(tag.data))) |
| return TranslateLastOpenSslError(); |
| tag_provided_ = true; |
| } |
| if (!tag_provided_) |
| return KM_ERROR_INVALID_TAG; |
| } |
| |
| return AesEvpOperation::Update(additional_params, input, output_params, output, input_consumed); |
| } |
| |
| inline bool is_bad_decrypt(unsigned long error) { |
| return (ERR_GET_LIB(error) == ERR_LIB_CIPHER && // |
| ERR_GET_REASON(error) == CIPHER_R_BAD_DECRYPT); |
| } |
| |
| keymaster_error_t AesEvpOperation::Finish(const AuthorizationSet& /* additional_params */, |
| const Buffer& /* signature */, |
| AuthorizationSet* /* output_params */, Buffer* output) { |
| output->reserve(AES_BLOCK_SIZE); |
| |
| int output_written = -1; |
| if (!EVP_CipherFinal_ex(&ctx_, output->peek_write(), &output_written)) { |
| if (block_mode_ == KM_MODE_GCM && is_bad_decrypt(ERR_peek_last_error())) |
| return KM_ERROR_VERIFICATION_FAILED; |
| LOG_E("Error encrypting final block: %s", ERR_error_string(ERR_peek_last_error(), NULL)); |
| return TranslateLastOpenSslError(); |
| } |
| |
| assert(output_written <= AES_BLOCK_SIZE); |
| output->advance_write(output_written); |
| return KM_ERROR_OK; |
| } |
| |
| keymaster_error_t AesEvpEncryptOperation::Finish(const AuthorizationSet& additional_params, |
| const Buffer& signature, |
| AuthorizationSet* output_params, Buffer* output) { |
| keymaster_error_t error = |
| AesEvpOperation::Finish(additional_params, signature, output_params, output); |
| if (error != KM_ERROR_OK) |
| return error; |
| |
| if (block_mode_ == KM_MODE_GCM && purpose() == KM_PURPOSE_ENCRYPT) { |
| uint8_t tag[tag_length_]; |
| if (!EVP_CIPHER_CTX_ctrl(&ctx_, EVP_CTRL_GCM_GET_TAG, tag_length_, tag)) |
| return TranslateLastOpenSslError(); |
| output_params->push_back(TAG_AEAD_TAG, tag, tag_length_); |
| } |
| |
| return KM_ERROR_OK; |
| } |
| keymaster_error_t AesEvpOperation::Abort() { |
| return KM_ERROR_OK; |
| } |
| |
| } // namespace keymaster |
