92 lines
3.3 KiB
C++
92 lines
3.3 KiB
C++
/*
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* Copyright (C) 2020 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "adb/pairing/aes_128_gcm.h"
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#include <android-base/endian.h>
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#include <android-base/logging.h>
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#include <openssl/evp.h>
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#include <openssl/hkdf.h>
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#include <openssl/rand.h>
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namespace adb {
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namespace pairing {
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namespace {
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// Size of AES-128-GCM key, in bytes
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static constexpr size_t kHkdfKeyLength = 16;
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} // namespace
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Aes128Gcm::Aes128Gcm(const uint8_t* key_material, size_t key_material_len) {
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CHECK(key_material);
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CHECK_NE(key_material_len, 0ul);
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uint8_t key[kHkdfKeyLength];
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uint8_t info[] = "adb pairing_auth aes-128-gcm key";
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CHECK_EQ(HKDF(key, sizeof(key), EVP_sha256(), key_material, key_material_len, nullptr, 0, info,
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sizeof(info) - 1),
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1);
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CHECK(EVP_AEAD_CTX_init(context_.get(), EVP_aead_aes_128_gcm(), key, sizeof(key),
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EVP_AEAD_DEFAULT_TAG_LENGTH, nullptr));
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}
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std::optional<size_t> Aes128Gcm::Encrypt(const uint8_t* in, size_t in_len, uint8_t* out,
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size_t out_len) {
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std::vector<uint8_t> nonce(EVP_AEAD_nonce_length(EVP_AEAD_CTX_aead(context_.get())), 0);
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memcpy(nonce.data(), &enc_sequence_, sizeof(enc_sequence_));
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size_t written_sz;
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if (!EVP_AEAD_CTX_seal(context_.get(), out, &written_sz, out_len, nonce.data(), nonce.size(),
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in, in_len, nullptr, 0)) {
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LOG(ERROR) << "Failed to encrypt (in_len=" << in_len << ", out_len=" << out_len
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<< ", out_len_needed=" << EncryptedSize(in_len) << ")";
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return std::nullopt;
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}
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++enc_sequence_;
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return written_sz;
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}
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std::optional<size_t> Aes128Gcm::Decrypt(const uint8_t* in, size_t in_len, uint8_t* out,
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size_t out_len) {
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std::vector<uint8_t> nonce(EVP_AEAD_nonce_length(EVP_AEAD_CTX_aead(context_.get())), 0);
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memcpy(nonce.data(), &dec_sequence_, sizeof(dec_sequence_));
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size_t written_sz;
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if (!EVP_AEAD_CTX_open(context_.get(), out, &written_sz, out_len, nonce.data(), nonce.size(),
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in, in_len, nullptr, 0)) {
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LOG(ERROR) << "Failed to decrypt (in_len=" << in_len << ", out_len=" << out_len
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<< ", out_len_needed=" << DecryptedSize(in_len) << ")";
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return std::nullopt;
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}
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++dec_sequence_;
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return written_sz;
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}
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size_t Aes128Gcm::EncryptedSize(size_t size) {
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// https://commondatastorage.googleapis.com/chromium-boringssl-docs/aead.h.html#EVP_AEAD_CTX_seal
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return size + EVP_AEAD_max_overhead(EVP_AEAD_CTX_aead(context_.get()));
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}
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size_t Aes128Gcm::DecryptedSize(size_t size) {
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// https://commondatastorage.googleapis.com/chromium-boringssl-docs/aead.h.html#EVP_AEAD_CTX_open
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return size;
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}
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} // namespace pairing
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} // namespace adb
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