Per discussion, implement the Omaha Client Update Protocol (CUP) in src/crypto.

crypto/cup_unittest.cc

+// Copyright (c) 2013 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 <limits>
+#include <vector>
+
+#include "base/base64.h"
+#include "crypto/cup.h"
+#include "crypto/random.h"
+#include "crypto/secure_util.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+std::string GetPublicKeyForTesting() {
+  // How to generate this key:
+  //   openssl genpkey -out cr.pem -outform PEM -algorithm RSA
+  //                   -pkeyopt rsa_keygen_pubexp:3
+  //   openssl rsa -in cr.pem -pubout -out cr_pub.pem
+
+  static const char kCupTestKey1024_Base64[] =
+    "MIGdMA0GCSqGSIb3DQEBAQUAA4GLADCBhwKBgQC7ct1JhLSol2DkBcJdNjR3KkEA"
+    "ZfXpF22lDD2WZu5JAZ4NiZqnHsKGJNPUbCH4AhFsXmuW5wEHhUVNhsMP6F9mQ06D"
+    "i+ygwZ8aXlklmW4S0Et+SNg3i73fnYn0KDQzrzJnMu46s/CFPhjr4f0TH9b7oHkU"
+    "XbqNZtG6gwaN1bmzFwIBAw==";
+
+  std::string result;
+  if (!base::Base64Decode(std::string(kCupTestKey1024_Base64), &result))
+    return "";
+
+  return result;
+}
+
+}  // end namespace
+
+#if defined(USE_OPENSSL)
+
+// Once CUP is implemented for OpenSSL, remove this #if block.
+TEST(CupUnitTest, OpenSSLStub) {
+  crypto::ClientUpdateProtocol cup;
+
+  std::string der_key;
+  EXPECT_FALSE(cup.Init(8, GetPublicKeyForTesting()));
+}
+
+#else
+
+namespace crypto {
+
+class CupUnitTest : public testing::Test {
+ protected:
+  virtual void SetUp() {
+    cup_.reset(ClientUpdateProtocol::Create(8, GetPublicKeyForTesting()));
+    ASSERT_TRUE(cup_.get());
+  }
+
+  void OverrideRAndRebuildKeys() {
+    // This must be the same length as the modulus of the public key being
+    // used in the unit test.
+    static const size_t kPublicKeyLength = 1024 / 8;
+    static const char kFixedR[] =
+      "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do "
+      "eiusmod tempor incididunt ut labore et dolore magna aliqua.    ";
+
+    ASSERT_EQ(kPublicKeyLength, strlen(kFixedR));
+    ASSERT_TRUE(cup_->BuildSharedKey(kPublicKeyLength,
+                                     reinterpret_cast<const uint8*>(kFixedR)));
+  }
+
+  ClientUpdateProtocol& CUP() {
+    return *cup_.get();
+  }
+
+ private:
+  scoped_ptr<ClientUpdateProtocol> cup_;
+};
+
+TEST_F(CupUnitTest, GetVersionedSecret) {
+  // Given a fixed public key set in our test fixture, if we override (r) with
+  // a known data, we should be able to test (w) against an expected output.
+  //
+  // This expected output can be generated using this command line, where
+  // plaintext.bin is the contents of kFixedR[] in OverrideRAndRebuildKeys():
+  //
+  //   openssl rsautl -inkey cr2_pub.pem -pubin -encrypt -raw
+  //                  -in plaintext.bin | base64
+  //
+  // Remember to prepend the key version number, and fix up the Base64
+  // afterwards to be URL-safe.
+
+  static const char kExpectedVW[] =
+    "8:lMmNR3mVbOitbq8ceYGStFBwrJcpvY-sauFSbMVe6VONS9x42xTOLY_KdqsWCy"
+    "KuiJBiQziQLOybPUyA9vk0N5kMnC90LIh2nP2FgFG0M0Z22qjB3drsdJPi7TQZbb"
+    "Xhqm587M8vjc6VlM_eoC0qYwCPaXBqXjsyiHnXetcn5X0";
+
+  EXPECT_NE(kExpectedVW, CUP().GetVersionedSecret());
+  OverrideRAndRebuildKeys();
+  EXPECT_EQ(kExpectedVW, CUP().GetVersionedSecret());
+}
+
+TEST_F(CupUnitTest, SignRequest) {
+  static const char kUrl[] = "//testserver.chromium.org/update";
+  static const char kUrlQuery[] = "?junk=present";
+  static const char kRequest[] = "testbody";
+
+  static const char kExpectedCP[] = "tfjmVMDAbU0-Kye4PjrCuyQIDCU";
+
+  OverrideRAndRebuildKeys();
+
+
+  // Check the case with no query string other than v|w.
+  std::string url(kUrl);
+  url.append("?w=");
+  url.append(CUP().GetVersionedSecret());
+
+  std::string cp;
+  EXPECT_TRUE(CUP().SignRequest(url, kRequest, &cp));
+
+  // Check the case with a pre-existing query string.
+  std::string url2(kUrl);
+  url2.append(kUrlQuery);
+  url2.append("&w=");
+  url2.append(CUP().GetVersionedSecret());
+
+  std::string cp2;
+  EXPECT_TRUE(CUP().SignRequest(url2, kRequest, &cp2));
+
+  // Changes in the URL should result in changes in the client proof.
+  EXPECT_EQ(kExpectedCP, cp2);
+  EXPECT_NE(cp, cp2);
+}
+
+TEST_F(CupUnitTest, ValidateResponse) {
+  static const char kUrl[] = "//testserver.chromium.orgupdate?junk=present&w=";
+  static const char kRequest[] = "testbody";
+
+  static const char kGoodResponse[] = "intact_response";
+  static const char kGoodC[] = "c=EncryptedDataFromTheUpdateServer";
+  static const char kGoodSP[] = "5rMFMPL9Hgqb-2J8kL3scsHeNgg";
+
+  static const char kBadResponse[] = "tampered_response";
+  static const char kBadC[] = "c=TotalJunkThatAnAttackerCouldSend";
+  static const char kBadSP[] = "Base64TamperedShaOneHash";
+
+  OverrideRAndRebuildKeys();
+
+  std::string url(kUrl);
+  url.append(CUP().GetVersionedSecret());
+
+  // We should return false if no calls to SignRequest() have been made.
+  EXPECT_FALSE(CUP().ValidateResponse(kGoodResponse, kGoodC, kGoodSP));
+
+  EXPECT_TRUE(CUP().SignRequest(url, kRequest, NULL));
+
+  // Return true on a valid response and server proof.
+  EXPECT_TRUE(CUP().ValidateResponse(kGoodResponse, kGoodC, kGoodSP));
+
+  // Return false on anything invalid.
+  EXPECT_FALSE(CUP().ValidateResponse(kBadResponse, kGoodC, kGoodSP));
+  EXPECT_FALSE(CUP().ValidateResponse(kGoodResponse, kBadC, kGoodSP));
+  EXPECT_FALSE(CUP().ValidateResponse(kGoodResponse, kGoodC, kBadSP));
+  EXPECT_FALSE(CUP().ValidateResponse(kGoodResponse, kBadC, kBadSP));
+  EXPECT_FALSE(CUP().ValidateResponse(kBadResponse, kGoodC, kBadSP));
+  EXPECT_FALSE(CUP().ValidateResponse(kBadResponse, kBadC, kGoodSP));
+  EXPECT_FALSE(CUP().ValidateResponse(kBadResponse, kBadC, kBadSP));
+}
+
+}  // namespace crypto
+
+#endif  // !defined(USE_OPENSSL)
+