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

crypto/cup_unittest.cc

Index: crypto/cup_unittest.cc
===================================================================
--- crypto/cup_unittest.cc	(revision 0)
+++ crypto/cup_unittest.cc	(revision 0)
@@ -0,0 +1,310 @@
+// 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/sha1.h"
+#include "crypto/cup.h"
+#include "crypto/random.h"
+#include "crypto/secure_util.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+// 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
+
+const char kCupTestKey1024PEM[] =
+  "MIGdMA0GCSqGSIb3DQEBAQUAA4GLADCBhwKBgQC7ct1JhLSol2DkBcJdNjR3KkEA"
+  "ZfXpF22lDD2WZu5JAZ4NiZqnHsKGJNPUbCH4AhFsXmuW5wEHhUVNhsMP6F9mQ06D"
+  "i+ygwZ8aXlklmW4S0Et+SNg3i73fnYn0KDQzrzJnMu46s/CFPhjr4f0TH9b7oHkU"
+  "XbqNZtG6gwaN1bmzFwIBAw==";
+
+const size_t kRsaKeySize = 128;
+
+}  // end namespace
+
+#if defined(USE_OPENSSL)
+
+// Once CUP is implemented for OpenSSL, remove this #if block.
+TEST(CupUnitTest, OpenSSLStub) {
+  crypto::ClientUpdateProtocol cup;
+  EXPECT_FALSE(cup.Init(8, kCupTestKey1024PEM));
+}
+
+#else
+
+namespace crypto {
+
+class CupUnitTest : public testing::Test {
+ protected:
+  virtual void SetUp() {
+    // 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
+
+    EXPECT_TRUE(cup_.Init(8, kCupTestKey1024PEM));
+  }
+
+  // Test RsaPad for a random message of num_bytes length.
+  void TestRsaPad(size_t num_bytes) {
+    std::vector<uint8> data(num_bytes);
+    crypto::RandBytes(&data.front(), data.size());
+
+    std::vector<uint8> m = ClientUpdateProtocol::RsaPad(kRsaKeySize, data);
+    ASSERT_EQ(m.size(), kRsaKeySize);
+
+    std::vector<uint8> hash(base::kSHA1Length);
+    base::SHA1HashBytes(&m.front(),
+                        static_cast<int>(m.size() - base::kSHA1Length),
+                        &hash.front());
+
+    EXPECT_TRUE(SecureMemEqual(&hash.front(),
+                               &m[kRsaKeySize - base::kSHA1Length],
+                               base::kSHA1Length));
+
+    EXPECT_FALSE(m[0] & 0x80);    // msb is always reset.
+    EXPECT_TRUE(m[0] & 0x60);     // bit next to msb is always set.
+  }
+
+  void TestUrlSafeB64Encode(const char* expected_input, const char* input) {
+    std::string expected(expected_input);
+    EXPECT_EQ(expected, UrlSafeB64Encode(reinterpret_cast<const uint8*>(input),
+                                         strlen(input)));
+  }
+
+  std::string UrlSafeB64Encode(const uint8* in_bytes, size_t length) {
+    std::vector<uint8> in(in_bytes, in_bytes + length);
+    return ClientUpdateProtocol::UrlSafeB64Encode(in);
+  }
+
+  std::vector<uint8> HashBin(const base::StringPiece& in_str) {
+    return ClientUpdateProtocol::Hash(in_str);
+  }
+
+  std::string Hash(const std::vector<uint8>& in_bytes) {
+    return BytesToHex(ClientUpdateProtocol::Hash(in_bytes));
+  }
+
+  std::string Hash(const base::StringPiece& in_str) {
+    return BytesToHex(ClientUpdateProtocol::Hash(in_str));
+  }
+
+  std::string SymSign(const std::vector<uint8>& key,
+                      uint8 id,
+                      const std::vector<uint8>* h1,
+                      const std::vector<uint8>* h2,
+                      const std::vector<uint8>* h3) {
+    return BytesToHex(ClientUpdateProtocol::SymSign(key, id, h1, h2, h3));
+  }
+
+  std::vector<uint8> SymSignRaw(const std::vector<uint8>& key,
+                      uint8 id,
+                      const std::vector<uint8>* h1,
+                      const std::vector<uint8>* h2,
+                      const std::vector<uint8>* h3) {
+    return ClientUpdateProtocol::SymSign(key, id, h1, h2, h3);
+  }
+
+  std::string BytesToHex(const std::vector<uint8>& bytes) {
+    std::string result;
+    if (bytes.size() < std::numeric_limits<size_t>::max() / 2) {
+      static const char kHexChars[] = "0123456789abcdef";
+      for (size_t i = 0; i < bytes.size(); ++i) {
+        result.push_back(kHexChars[(bytes[i] >> 4)]);
+        result.push_back(kHexChars[(bytes[i] & 0xf)]);
+      }
+    }
+    return result;
+  }
+
+  void OverrideRAndRebuildKeys() {
+    static const char kFixedR[] =
+      "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do "
+      "eiusmod tempor incididunt ut labore et dolore magna aliqua.    ";
+
+    const std::string plaintext(kFixedR);
+    cup_.r_.assign(plaintext.begin(), plaintext.end());
+    EXPECT_TRUE(cup_.BuildSharedKey());
+  }
+
+  const std::string& ExamineVW() {
+    return cup_.vw_;
+  }
+
+  ClientUpdateProtocol& GetCup() {
+    return cup_;
+  }
+
+
+ private:
+  ClientUpdateProtocol cup_;
+};
+
+TEST_F(CupUnitTest, RsaPad) {
+  ASSERT_GE(kRsaKeySize, base::kSHA1Length);
+
+  TestRsaPad(1);                   // 1 byte.
+  TestRsaPad(base::kSHA1Length);   // 20 bytes.
+  TestRsaPad(kRsaKeySize);         // 128 bytes.
+  TestRsaPad(1000);                // 1000 bytes.
+}
+
+TEST_F(CupUnitTest, B64Encode) {
+  TestUrlSafeB64Encode("MQ", "1");
+  TestUrlSafeB64Encode("MTI", "12");
+  TestUrlSafeB64Encode("MTIz", "123");
+  TestUrlSafeB64Encode("PHA-SGk_PC9wPg", "<p>Hi?</p>");
+  TestUrlSafeB64Encode("R29vZ2xlIEluYw", "Google Inc");
+}
+
+TEST_F(CupUnitTest, Hash) {
+  static const char kPlainText[] =
+      "The quick brown fox jumps over the lazy dog";
+
+  // Empty vector.
+  std::vector<uint8> data;
+  EXPECT_EQ("da39a3ee5e6b4b0d3255bfef95601890afd80709",
+            Hash(data));
+
+  // Non-empty vector.
+  const uint8* first = reinterpret_cast<const uint8*>(kPlainText);
+  const uint8* last  = first + strlen(kPlainText);
+  data.clear();
+  data.insert(data.begin(), first, last);
+  EXPECT_EQ("2fd4e1c67a2d28fced849ee1bb76e7391b93eb12",
+            Hash(data));
+
+  // Empty string.
+  EXPECT_EQ("da39a3ee5e6b4b0d3255bfef95601890afd80709",
+            Hash(std::string()));
+
+  // Non-empty string.
+  EXPECT_EQ("2fd4e1c67a2d28fced849ee1bb76e7391b93eb12",
+            Hash(std::string(kPlainText)));
+}
+
+TEST_F(CupUnitTest, SymSign) {
+  static const char kPlainText[] =
+      "The quick brown fox jumps over the lazy dog";
+
+  std::vector<uint8> key;
+  key.push_back(7);
+
+  std::vector<uint8> hash = HashBin(std::string(kPlainText));
+
+  // Verify that NULL buffers are not included in the hash.
+  EXPECT_EQ("1c6fa359c0a7b11421ae4d31a92f9de8a4ef8d2d",
+            SymSign(key, 1, &hash, NULL, NULL));
+  EXPECT_EQ("1c6fa359c0a7b11421ae4d31a92f9de8a4ef8d2d",
+            SymSign(key, 1, NULL, &hash, NULL));
+  EXPECT_EQ("1c6fa359c0a7b11421ae4d31a92f9de8a4ef8d2d",
+            SymSign(key, 1, NULL, &hash, NULL));
+
+  // Verify that all three buffers are included in the hash.
+  EXPECT_EQ("fef3e343795946cd47ff4e07eca5f3f09b051d86",
+            SymSign(key, 1, &hash, &hash, &hash));
+}
+
+TEST_F(CupUnitTest, EncryptSharedKey) {
+  // 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, ExamineVW());
+  OverrideRAndRebuildKeys();
+  EXPECT_EQ(kExpectedVW, ExamineVW());
+}
+
+TEST_F(CupUnitTest, SignRequest) {
+  static const char kUrlHost[] = "testserver.chromium.org";
+  static const char kUrlPath[] = "update";
+  static const char kUrlQuery[] = "?junk=present";
+  static const char kRequest[] = "testbody";
+
+  static const char kExpectedCP[] = "hIxzNIHv4pg03NcXPLuATX8G2SI";
+
+  OverrideRAndRebuildKeys();
+
+  std::string cup_query;
+  std::string cp;
+
+  // Check the case with a preexisting query string.
+  EXPECT_TRUE(GetCup().SignRequest(kUrlHost, kUrlPath, kUrlQuery, kRequest,
+                                   &cup_query, &cp));
+
+  std::string expected_query(kUrlQuery);
+  expected_query.append("&w=");
+  expected_query.append(ExamineVW());
+  EXPECT_EQ(expected_query, cup_query);
+  EXPECT_EQ(kExpectedCP, cp);
+
+  // Check the case with no query string.
+  std::string cp2;
+  EXPECT_TRUE(GetCup().SignRequest(kUrlHost, kUrlPath, std::string(), kRequest,
+                                   &cup_query, &cp2));
+  expected_query = "?w=";
+  expected_query.append(ExamineVW());
+  EXPECT_EQ(expected_query, cup_query);
+
+  // Changes in the URL should result in changes in the client proof.
+  EXPECT_NE(cp, cp2);
+}
+
+TEST_F(CupUnitTest, ValidateResponse) {
+  static const char kUrlHost[] = "testserver.chromium.org";
+  static const char kUrlPath[] = "update";
+  static const char kUrlQuery[] = "?junk=present";
+  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();
+
+  // We should return false if no calls to SignRequest() have been made.
+  EXPECT_FALSE(GetCup().ValidateResponse(kGoodResponse, kGoodC, kGoodSP));
+
+  EXPECT_TRUE(GetCup().SignRequest(kUrlHost, kUrlPath, kUrlQuery, kRequest,
+                                   NULL, NULL));
+
+  // Return true on a valid response and server proof.
+  EXPECT_TRUE(GetCup().ValidateResponse(kGoodResponse, kGoodC, kGoodSP));
+
+  // Return false on anything invalid.
+  EXPECT_FALSE(GetCup().ValidateResponse(kBadResponse, kGoodC, kGoodSP));
+  EXPECT_FALSE(GetCup().ValidateResponse(kGoodResponse, kBadC, kGoodSP));
+  EXPECT_FALSE(GetCup().ValidateResponse(kGoodResponse, kGoodC, kBadSP));
+  EXPECT_FALSE(GetCup().ValidateResponse(kGoodResponse, kBadC, kBadSP));
+  EXPECT_FALSE(GetCup().ValidateResponse(kBadResponse, kGoodC, kBadSP));
+  EXPECT_FALSE(GetCup().ValidateResponse(kBadResponse, kBadC, kGoodSP));
+  EXPECT_FALSE(GetCup().ValidateResponse(kBadResponse, kBadC, kBadSP));
+}
+
+}  // namespace crypto
+
+#endif  // !defined(USE_OPENSSL)
+