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// Copyright 2019 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 "util/crypto/certificate_utils.h"
#include <openssl/asn1.h>
#include <openssl/bio.h>
#include <openssl/crypto.h>
#include <openssl/evp.h>
#include <openssl/rsa.h>
#include <openssl/ssl.h>
#include <time.h>
#include <atomic>
#include <string>
#include "util/crypto/openssl_util.h"
#include "util/crypto/sha2.h"
namespace openscreen {
namespace {
// Returns whether or not the certificate field successfully was added.
bool AddCertificateField(X509_NAME* certificate_name,
absl::string_view field,
absl::string_view value) {
return X509_NAME_add_entry_by_txt(
certificate_name, std::string(field).c_str(), MBSTRING_ASC,
reinterpret_cast<const unsigned char*>(value.data()),
value.length(), -1, 0) == 1;
}
bssl::UniquePtr<ASN1_TIME> ToAsn1Time(std::chrono::seconds time_since_epoch) {
return bssl::UniquePtr<ASN1_TIME>(
ASN1_TIME_set(nullptr, time_since_epoch.count()));
}
bssl::UniquePtr<X509> CreateCertificateInternal(
absl::string_view name,
std::chrono::seconds certificate_duration,
EVP_PKEY key_pair,
std::chrono::seconds time_since_unix_epoch) {
bssl::UniquePtr<X509> certificate(X509_new());
// Serial numbers must be unique for this session. As a pretend CA, we should
// not issue certificates with the same serial number in the same session.
static std::atomic_int serial_number(1);
if (ASN1_INTEGER_set(X509_get_serialNumber(certificate.get()),
serial_number++) != 1) {
return nullptr;
}
const bssl::UniquePtr<ASN1_TIME> now(ToAsn1Time(time_since_unix_epoch));
const bssl::UniquePtr<ASN1_TIME> expiration_time(
ToAsn1Time(time_since_unix_epoch + certificate_duration));
if ((X509_set_notBefore(certificate.get(), now.get()) != 1) ||
(X509_set_notAfter(certificate.get(), expiration_time.get()) != 1)) {
return nullptr;
}
X509_NAME* certificate_name = X509_get_subject_name(certificate.get());
if (!AddCertificateField(certificate_name, "CN", name)) {
return nullptr;
}
if ((X509_set_issuer_name(certificate.get(), certificate_name) != 1) ||
(X509_set_pubkey(certificate.get(), &key_pair) != 1) ||
// Unlike all of the other BoringSSL methods here, X509_sign returns
// the size of the signature in bytes.
(X509_sign(certificate.get(), &key_pair, EVP_sha256()) <= 0) ||
(X509_verify(certificate.get(), &key_pair) != 1)) {
return nullptr;
}
return certificate;
}
} // namespace
ErrorOr<bssl::UniquePtr<X509>> CreateCertificate(
absl::string_view name,
std::chrono::seconds duration,
const EVP_PKEY& key_pair,
std::chrono::seconds time_since_unix_epoch) {
bssl::UniquePtr<X509> certificate = CreateCertificateInternal(
name, duration, key_pair, time_since_unix_epoch);
if (!certificate) {
return Error::Code::kCertificateCreationError;
}
return certificate;
}
ErrorOr<std::vector<uint8_t>> ExportCertificate(const X509& certificate) {
unsigned char* buffer = nullptr;
// Casting-away the const because the legacy i2d_X509() function is not
// const-correct.
X509* const certificate_ptr = const_cast<X509*>(&certificate);
const int len = i2d_X509(certificate_ptr, &buffer);
if (len <= 0) {
return Error::Code::kCertificateValidationError;
}
std::vector<uint8_t> raw_der_certificate(buffer, buffer + len);
// BoringSSL doesn't free the temporary buffer.
OPENSSL_free(buffer);
return raw_der_certificate;
}
ErrorOr<bssl::UniquePtr<X509>> ImportCertificate(const uint8_t* der_x509_cert,
int der_x509_cert_length) {
if (!der_x509_cert) {
return Error::Code::kErrCertsMissing;
}
bssl::UniquePtr<X509> certificate(
d2i_X509(nullptr, &der_x509_cert, der_x509_cert_length));
if (!certificate) {
return Error::Code::kCertificateValidationError;
}
return certificate;
}
std::string GetSpkiTlv(X509* cert) {
int len = i2d_X509_PUBKEY(cert->cert_info->key, nullptr);
if (len <= 0) {
return {};
}
std::string x(len, 0);
uint8_t* data = reinterpret_cast<uint8_t*>(&x[0]);
if (!i2d_X509_PUBKEY(cert->cert_info->key, &data)) {
return {};
}
return x;
}
ErrorOr<uint64_t> ParseDerUint64(ASN1_INTEGER* asn1int) {
if (asn1int->length > 8 || asn1int->length == 0) {
return Error::Code::kParameterInvalid;
}
uint64_t result = 0;
for (int i = 0; i < asn1int->length; ++i) {
result = (result << 8) | asn1int->data[i];
}
return result;
}
} // namespace openscreen
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