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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40285824): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
#include "remoting/protocol/auth_util.h"
#include "base/base64.h"
#include "base/logging.h"
#include "base/strings/string_util.h"
#include "crypto/hmac.h"
#include "crypto/sha2.h"
#include "net/base/net_errors.h"
#include "net/socket/ssl_socket.h"
namespace remoting::protocol {
const char kClientAuthSslExporterLabel[] =
"EXPORTER-remoting-channel-auth-client";
const char kHostAuthSslExporterLabel[] = "EXPORTER-remoting-channel-auth-host";
const char kSslFakeHostName[] = "chromoting";
std::string GetSharedSecretHash(const std::string& tag,
const std::string& shared_secret) {
crypto::HMAC response(crypto::HMAC::SHA256);
if (!response.Init(tag)) {
LOG(FATAL) << "HMAC::Init failed";
}
unsigned char out_bytes[kSharedSecretHashLength];
if (!response.Sign(shared_secret, out_bytes, sizeof(out_bytes))) {
LOG(FATAL) << "HMAC::Sign failed";
}
return std::string(out_bytes, out_bytes + sizeof(out_bytes));
}
// static
std::string GetAuthBytes(net::SSLSocket* socket,
const std::string_view& label,
const std::string_view& shared_secret) {
// Get keying material from SSL.
std::array<uint8_t, kAuthDigestLength> key_material;
int export_result =
socket->ExportKeyingMaterial(label, std::nullopt, key_material);
if (export_result != net::OK) {
LOG(ERROR) << "Error fetching keying material: " << export_result;
return std::string();
}
// Generate auth digest based on the keying material and shared secret.
crypto::HMAC response(crypto::HMAC::SHA256);
if (!response.Init(key_material.data(), kAuthDigestLength)) {
NOTREACHED() << "HMAC::Init failed";
}
unsigned char out_bytes[kAuthDigestLength];
if (!response.Sign(shared_secret, out_bytes, kAuthDigestLength)) {
NOTREACHED() << "HMAC::Sign failed";
}
return std::string(out_bytes, out_bytes + kAuthDigestLength);
}
} // namespace remoting::protocol
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