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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/sharing_message/web_push/json_web_token_util.h"
#include <stdint.h>
#include "base/base64url.h"
#include "base/json/json_writer.h"
#include "base/logging.h"
#include "base/strings/strcat.h"
#include "crypto/ec_private_key.h"
#include "crypto/ec_signature_creator.h"
namespace {
const char kKeyAlg[] = "alg";
const char kAlgES256[] = "ES256";
const char kKeyTyp[] = "typ";
const char kTypJwt[] = "JWT";
} // namespace
std::optional<std::string> CreateJSONWebToken(
const base::Value::Dict& claims,
crypto::ECPrivateKey* private_key) {
// Generate header.
base::Value::Dict header;
header.Set(kKeyAlg, base::Value(kAlgES256));
header.Set(kKeyTyp, base::Value(kTypJwt));
// Serialize header.
std::string header_serialized;
if (!base::JSONWriter::Write(header, &header_serialized)) {
LOG(ERROR) << "Failed to write header as JSON";
return std::nullopt;
}
std::string header_base64;
base::Base64UrlEncode(header_serialized,
base::Base64UrlEncodePolicy::OMIT_PADDING,
&header_base64);
// Serialize claims as payload.
std::string payload_serialized;
if (!base::JSONWriter::Write(claims, &payload_serialized)) {
LOG(ERROR) << "Failed to write claims as JSON";
return std::nullopt;
}
std::string payload_base64;
base::Base64UrlEncode(payload_serialized,
base::Base64UrlEncodePolicy::OMIT_PADDING,
&payload_base64);
std::string data = base::StrCat({header_base64, ".", payload_base64});
// Create signature.
auto signer = crypto::ECSignatureCreator::Create(private_key);
std::vector<uint8_t> der_signature, raw_signature;
if (!signer->Sign(base::as_byte_span(data), &der_signature)) {
LOG(ERROR) << "Failed to create DER signature";
return std::nullopt;
}
if (!signer->DecodeSignature(der_signature, &raw_signature)) {
LOG(ERROR) << "Failed to decode DER signature";
return std::nullopt;
}
// Serialize signature.
std::string signature_base64;
base::Base64UrlEncode(std::string(raw_signature.begin(), raw_signature.end()),
base::Base64UrlEncodePolicy::OMIT_PADDING,
&signature_base64);
return base::StrCat({data, ".", signature_base64});
}
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