components/certificate_reporting/error_reporter.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "components/certificate_reporting/error_reporter.h"
   6
   7 #include <set>
   8
   9 #include "base/logging.h"
  10 #include "components/certificate_reporting/encrypted_cert_logger.pb.h"
  11
  12 #if defined(USE_OPENSSL)
  13 #include "crypto/aead_openssl.h"
  14 #endif
  15
  16 #include "crypto/curve25519.h"
  17 #include "crypto/hkdf.h"
  18 #include "crypto/random.h"
  19 #include "net/url_request/certificate_report_sender.h"
  20
  21 namespace certificate_reporting {
  22
  23 namespace {
  24
  25 // Constants used for crypto. The corresponding private key is used by
  26 // the SafeBrowsing client-side detection server to decrypt reports.
  27 static const uint8 kServerPublicKey[] = {
  28     0x51, 0xcc, 0x52, 0x67, 0x42, 0x47, 0x3b, 0x10, 0xe8, 0x63, 0x18,
  29     0x3c, 0x61, 0xa7, 0x96, 0x76, 0x86, 0x91, 0x40, 0x71, 0x39, 0x5f,
  30     0x31, 0x1a, 0x39, 0x5b, 0x76, 0xb1, 0x6b, 0x3d, 0x6a, 0x2b};
  31 static const uint32 kServerPublicKeyVersion = 1;
  32
  33 #if defined(USE_OPENSSL)
  34
  35 static const char kHkdfLabel[] = "certificate report";
  36
  37 std::string GetHkdfSubkeySecret(size_t subkey_length,
  38                                 const uint8* private_key,
  39                                 const uint8* public_key) {
  40   uint8 shared_secret[crypto::curve25519::kBytes];
  41   crypto::curve25519::ScalarMult(private_key, public_key, shared_secret);
  42
  43   // By mistake, the HKDF label here ends up with an extra null byte on
  44   // the end, due to using sizeof(kHkdfLabel) in the StringPiece
  45   // constructor instead of strlen(kHkdfLabel). Ideally this code should
  46   // be just passing kHkdfLabel directly into the HKDF constructor.
  47   //
  48   // TODO(estark): fix this in coordination with the server-side code --
  49   // perhaps by rolling the public key version forward and using the
  50   // version to decide whether to use the extra-null-byte version of the
  51   // label. https://crbug.com/517746
  52   crypto::HKDF hkdf(base::StringPiece(reinterpret_cast<char*>(shared_secret),
  53                                       sizeof(shared_secret)),
  54                     "" /* salt */,
  55                     base::StringPiece(kHkdfLabel, sizeof(kHkdfLabel)),
  56                     0 /* key bytes */, 0 /* iv bytes */, subkey_length);
  57
  58   return hkdf.subkey_secret().as_string();
  59 }
  60
  61 bool EncryptSerializedReport(const uint8* server_public_key,
  62                              uint32 server_public_key_version,
  63                              const std::string& report,
  64                              EncryptedCertLoggerRequest* encrypted_report) {
  65   // Generate an ephemeral key pair to generate a shared secret.
  66   uint8 public_key[crypto::curve25519::kBytes];
  67   uint8 private_key[crypto::curve25519::kScalarBytes];
  68
  69   crypto::RandBytes(private_key, sizeof(private_key));
  70   crypto::curve25519::ScalarBaseMult(private_key, public_key);
  71
  72   crypto::Aead aead(crypto::Aead::AES_128_CTR_HMAC_SHA256);
  73   const std::string key =
  74       GetHkdfSubkeySecret(aead.KeyLength(), private_key,
  75                           reinterpret_cast<const uint8*>(server_public_key));
  76   aead.Init(&key);
  77
  78   // Use an all-zero nonce because the key is random per-message.
  79   std::string nonce(aead.NonceLength(), '\0');
  80
  81   std::string ciphertext;
  82   if (!aead.Seal(report, nonce, std::string(), &ciphertext)) {
  83     LOG(ERROR) << "Error sealing certificate report.";
  84     return false;
  85   }
  86
  87   encrypted_report->set_encrypted_report(ciphertext);
  88   encrypted_report->set_server_public_key_version(server_public_key_version);
  89   encrypted_report->set_client_public_key(reinterpret_cast<char*>(public_key),
  90                                           sizeof(public_key));
  91   encrypted_report->set_algorithm(
  92       EncryptedCertLoggerRequest::AEAD_ECDH_AES_128_CTR_HMAC_SHA256);
  93   return true;
  94 }
  95 #endif
  96
  97 }  // namespace
  98
  99 ErrorReporter::ErrorReporter(
 100     net::URLRequestContext* request_context,
 101     const GURL& upload_url,
 102     net::CertificateReportSender::CookiesPreference cookies_preference)
 103     : ErrorReporter(upload_url,
 104                     kServerPublicKey,
 105                     kServerPublicKeyVersion,
 106                     make_scoped_ptr(new net::CertificateReportSender(
 107                         request_context,
 108                         cookies_preference))) {}
 109
 110 ErrorReporter::ErrorReporter(
 111     const GURL& upload_url,
 112     const uint8 server_public_key[/* 32 */],
 113     const uint32 server_public_key_version,
 114     scoped_ptr<net::CertificateReportSender> certificate_report_sender)
 115     : certificate_report_sender_(certificate_report_sender.Pass()),
 116       upload_url_(upload_url),
 117       server_public_key_(server_public_key),
 118       server_public_key_version_(server_public_key_version) {
 119   DCHECK(certificate_report_sender_);
 120   DCHECK(!upload_url.is_empty());
 121 }
 122
 123 ErrorReporter::~ErrorReporter() {}
 124
 125 void ErrorReporter::SendExtendedReportingReport(
 126     const std::string& serialized_report) {
 127   if (upload_url_.SchemeIsCryptographic()) {
 128     certificate_report_sender_->Send(upload_url_, serialized_report);
 129   } else {
 130     DCHECK(IsHttpUploadUrlSupported());
 131 #if defined(USE_OPENSSL)
 132     EncryptedCertLoggerRequest encrypted_report;
 133     if (!EncryptSerializedReport(server_public_key_, server_public_key_version_,
 134                                  serialized_report, &encrypted_report)) {
 135       LOG(ERROR) << "Failed to encrypt serialized report.";
 136       return;
 137     }
 138     std::string serialized_encrypted_report;
 139     encrypted_report.SerializeToString(&serialized_encrypted_report);
 140     certificate_report_sender_->Send(upload_url_, serialized_encrypted_report);
 141 #endif
 142   }
 143 }
 144
 145 bool ErrorReporter::IsHttpUploadUrlSupported() {
 146 #if defined(USE_OPENSSL)
 147   return true;
 148 #else
 149   return false;
 150 #endif
 151 }
 152
 153 // Used only by tests.
 154 #if defined(USE_OPENSSL)
 155 bool ErrorReporter::DecryptErrorReport(
 156     const uint8 server_private_key[32],
 157     const EncryptedCertLoggerRequest& encrypted_report,
 158     std::string* decrypted_serialized_report) {
 159   crypto::Aead aead(crypto::Aead::AES_128_CTR_HMAC_SHA256);
 160   const std::string key =
 161       GetHkdfSubkeySecret(aead.KeyLength(), server_private_key,
 162                           reinterpret_cast<const uint8*>(
 163                               encrypted_report.client_public_key().data()));
 164   aead.Init(&key);
 165
 166   // Use an all-zero nonce because the key is random per-message.
 167   std::string nonce(aead.NonceLength(), 0);
 168
 169   return aead.Open(encrypted_report.encrypted_report(), nonce, std::string(),
 170                    decrypted_serialized_report);
 171 }
 172 #endif
 173
 174 }  // namespace certificate_reporting