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// Copyright 2020 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "cast/receiver/channel/static_credentials.h"
#include <openssl/mem.h>
#include <openssl/pem.h>
#include <cstdio>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "platform/base/tls_credentials.h"
#include "util/crypto/certificate_utils.h"
#include "util/osp_logging.h"
namespace openscreen {
namespace cast {
namespace {
using FileUniquePtr = std::unique_ptr<FILE, decltype(&fclose)>;
constexpr char kGeneratedRootCertificateName[] =
"generated_root_cast_receiver.crt";
constexpr char kGeneratedPrivateKey[] = "generated_root_cast_receiver.key";
constexpr int kThreeDaysInSeconds = 3 * 24 * 60 * 60;
constexpr auto kCertificateDuration = std::chrono::seconds(kThreeDaysInSeconds);
ErrorOr<GeneratedCredentials> GenerateCredentials(
std::string device_certificate_id,
EVP_PKEY* root_key,
X509* root_cert) {
OSP_CHECK(root_key);
OSP_CHECK(root_cert);
bssl::UniquePtr<EVP_PKEY> intermediate_key = GenerateRsaKeyPair();
bssl::UniquePtr<EVP_PKEY> device_key = GenerateRsaKeyPair();
OSP_CHECK(intermediate_key);
OSP_CHECK(device_key);
ErrorOr<bssl::UniquePtr<X509>> intermediate_cert_or_error =
CreateSelfSignedX509Certificate(
"Cast Intermediate", kCertificateDuration, *intermediate_key,
GetWallTimeSinceUnixEpoch(), true, root_cert, root_key);
OSP_CHECK(intermediate_cert_or_error);
bssl::UniquePtr<X509> intermediate_cert =
std::move(intermediate_cert_or_error.value());
ErrorOr<bssl::UniquePtr<X509>> device_cert_or_error =
CreateSelfSignedX509Certificate(
device_certificate_id, kCertificateDuration, *device_key,
GetWallTimeSinceUnixEpoch(), false, intermediate_cert.get(),
intermediate_key.get());
OSP_CHECK(device_cert_or_error);
bssl::UniquePtr<X509> device_cert = std::move(device_cert_or_error.value());
// Device cert chain plumbing + serialization.
DeviceCredentials device_creds;
device_creds.private_key = std::move(device_key);
int cert_length = i2d_X509(device_cert.get(), nullptr);
std::string cert_serial(cert_length, 0);
uint8_t* out = reinterpret_cast<uint8_t*>(&cert_serial[0]);
i2d_X509(device_cert.get(), &out);
device_creds.certs.emplace_back(std::move(cert_serial));
cert_length = i2d_X509(intermediate_cert.get(), nullptr);
cert_serial.resize(cert_length);
out = reinterpret_cast<uint8_t*>(&cert_serial[0]);
i2d_X509(intermediate_cert.get(), &out);
device_creds.certs.emplace_back(std::move(cert_serial));
cert_length = i2d_X509(root_cert, nullptr);
std::vector<uint8_t> trust_anchor_der(cert_length);
out = &trust_anchor_der[0];
i2d_X509(root_cert, &out);
// TLS key pair + certificate generation.
bssl::UniquePtr<EVP_PKEY> tls_key = GenerateRsaKeyPair();
OSP_CHECK_EQ(EVP_PKEY_id(tls_key.get()), EVP_PKEY_RSA);
ErrorOr<bssl::UniquePtr<X509>> tls_cert_or_error =
CreateSelfSignedX509Certificate("Test Device TLS", kCertificateDuration,
*tls_key, GetWallTimeSinceUnixEpoch());
OSP_CHECK(tls_cert_or_error);
bssl::UniquePtr<X509> tls_cert = std::move(tls_cert_or_error.value());
// TLS private key serialization.
RSA* rsa_key = EVP_PKEY_get0_RSA(tls_key.get());
size_t pkey_len = 0;
uint8_t* pkey_bytes = nullptr;
OSP_CHECK(RSA_private_key_to_bytes(&pkey_bytes, &pkey_len, rsa_key));
OSP_CHECK_GT(pkey_len, 0u);
std::vector<uint8_t> tls_key_serial(pkey_bytes, pkey_bytes + pkey_len);
OPENSSL_free(pkey_bytes);
// TLS public key serialization.
pkey_len = 0;
pkey_bytes = nullptr;
OSP_CHECK(RSA_public_key_to_bytes(&pkey_bytes, &pkey_len, rsa_key));
OSP_CHECK_GT(pkey_len, 0u);
std::vector<uint8_t> tls_pub_serial(pkey_bytes, pkey_bytes + pkey_len);
OPENSSL_free(pkey_bytes);
// TLS cert serialization.
cert_length = 0;
cert_length = i2d_X509(tls_cert.get(), nullptr);
OSP_CHECK_GT(cert_length, 0);
std::vector<uint8_t> tls_cert_serial(cert_length);
out = &tls_cert_serial[0];
i2d_X509(tls_cert.get(), &out);
auto provider = std::make_unique<StaticCredentialsProvider>(
std::move(device_creds), tls_cert_serial);
return GeneratedCredentials{
std::move(provider),
TlsCredentials{std::move(tls_key_serial), std::move(tls_pub_serial),
std::move(tls_cert_serial)},
std::move(trust_anchor_der)};
}
bssl::UniquePtr<EVP_PKEY> GeneratePrivateKey() {
bssl::UniquePtr<EVP_PKEY> root_key = GenerateRsaKeyPair();
OSP_CHECK(root_key);
return root_key;
}
bssl::UniquePtr<X509> GenerateRootCert(const EVP_PKEY& root_key) {
ErrorOr<bssl::UniquePtr<X509>> root_cert_or_error =
CreateSelfSignedX509Certificate("Cast Root CA", kCertificateDuration,
root_key, GetWallTimeSinceUnixEpoch(),
true);
OSP_CHECK(root_cert_or_error);
return std::move(root_cert_or_error.value());
}
} // namespace
StaticCredentialsProvider::StaticCredentialsProvider() = default;
StaticCredentialsProvider::StaticCredentialsProvider(
DeviceCredentials device_creds,
std::vector<uint8_t> tls_cert_der)
: device_creds(std::move(device_creds)),
tls_cert_der(std::move(tls_cert_der)) {}
StaticCredentialsProvider::StaticCredentialsProvider(
StaticCredentialsProvider&&) = default;
StaticCredentialsProvider& StaticCredentialsProvider::operator=(
StaticCredentialsProvider&&) = default;
StaticCredentialsProvider::~StaticCredentialsProvider() = default;
void GenerateDeveloperCredentialsToFile() {
bssl::UniquePtr<EVP_PKEY> root_key = GeneratePrivateKey();
bssl::UniquePtr<X509> root_cert = GenerateRootCert(*root_key);
FileUniquePtr f(fopen(kGeneratedPrivateKey, "w"), &fclose);
if (PEM_write_PrivateKey(f.get(), root_key.get(), nullptr, nullptr, 0, 0,
nullptr) != 1) {
OSP_LOG_ERROR << "Failed to write private key, check permissions?";
return;
}
OSP_LOG_INFO << "Generated new private key for session: ./"
<< kGeneratedPrivateKey;
FileUniquePtr cert_file(fopen(kGeneratedRootCertificateName, "w"), &fclose);
if (PEM_write_X509(cert_file.get(), root_cert.get()) != 1) {
OSP_LOG_ERROR << "Failed to write root certificate, check permissions?";
return;
}
OSP_LOG_INFO << "Generated new root certificate for session: ./"
<< kGeneratedRootCertificateName;
}
ErrorOr<GeneratedCredentials> GenerateCredentialsForTesting(
const std::string& device_certificate_id) {
bssl::UniquePtr<EVP_PKEY> root_key = GeneratePrivateKey();
bssl::UniquePtr<X509> root_cert = GenerateRootCert(*root_key);
return GenerateCredentials(device_certificate_id, root_key.get(),
root_cert.get());
}
ErrorOr<GeneratedCredentials> GenerateCredentials(
const std::string& device_certificate_id,
const std::string& private_key_path,
const std::string& server_certificate_path) {
if (private_key_path.empty() || server_certificate_path.empty()) {
return Error(Error::Code::kParameterInvalid,
"Missing either private key or server certificate");
}
FileUniquePtr key_file(fopen(private_key_path.c_str(), "r"), &fclose);
if (!key_file) {
return Error(Error::Code::kParameterInvalid,
"Missing private key file path");
}
bssl::UniquePtr<EVP_PKEY> root_key =
bssl::UniquePtr<EVP_PKEY>(PEM_read_PrivateKey(
key_file.get(), nullptr /* x */, nullptr /* cb */, nullptr /* u */));
FileUniquePtr cert_file(fopen(server_certificate_path.c_str(), "r"), &fclose);
if (!cert_file) {
return Error(Error::Code::kParameterInvalid,
"Missing server certificate file path");
}
bssl::UniquePtr<X509> root_cert = bssl::UniquePtr<X509>(PEM_read_X509(
cert_file.get(), nullptr /* x */, nullptr /* cb */, nullptr /* u */));
return GenerateCredentials(device_certificate_id, root_key.get(),
root_cert.get());
}
} // namespace cast
} // namespace openscreen
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