Move cryptohome_library to src/chromeos

chromeos/cryptohome/cryptohome_library.cc

 // Copyright (c) 2012 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 "chrome/browser/chromeos/cros/cryptohome_library.h"
+#include "chromeos/cryptohome/cryptohome_library.h"
 
 #include <map>
 
 #include "base/bind.h"
+#include "base/chromeos/chromeos_version.h"
 #include "base/memory/weak_ptr.h"
 #include "base/string_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "chromeos/dbus/cryptohome_client.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
+#include "crypto/encryptor.h"
+#include "crypto/nss_util.h"
+#include "crypto/sha2.h"
+#include "crypto/symmetric_key.h"
 
 namespace chromeos {
 
 namespace {
 
 const char kStubSystemSalt[] = "stub_system_salt";
+const size_t kKeySize = 16;

[Ryan Sleevi, 2013/04/26 18:38:20]

nit: This is really kNonceSize.

A bit confusing, given that kKeySize suggests its for the DeriveKeyFromPassword
(which takes a key size *in bits*), and which is hardcoded at 256 bits on line
175.

 
 // Does nothing.  Used as a Cryptohome::VoidMethodCallback.
 void DoNothing(DBusMethodCallStatus call_status) {}
 
 }  // namespace
 
 // This class handles the interaction with the ChromeOS cryptohome library APIs.
 class CryptohomeLibraryImpl : public CryptohomeLibrary {
  public:
   CryptohomeLibraryImpl() : weak_ptr_factory_(this) {
@@ skipping 78 matching lines @@
     return result;
   }
 
   virtual std::string GetSystemSalt() OVERRIDE {
     LoadSystemSalt();  // no-op if it's already loaded.
     return StringToLowerASCII(base::HexEncode(
         reinterpret_cast<const void*>(system_salt_.data()),
         system_salt_.size()));
   }
 
+  virtual std::string EncryptWithSystemSalt(const std::string& token) OVERRIDE {
+    // Don't care about token encryption while debugging.
+    if (!base::chromeos::IsRunningOnChromeOS())
+      return token;
+
+    if (!LoadSystemSaltKey()) {
+      LOG(WARNING) << "System salt key is not available for encrypt.";
+      return std::string();
+    }
+    return EncryptTokenWithKey(system_salt_key_.get(),
+                               GetSystemSalt(),
+                               token);
+  }
+
+  virtual std::string DecryptWithSystemSalt(
+      const std::string& encrypted_token_hex) OVERRIDE {
+    // Don't care about token encryption while debugging.
+    if (!base::chromeos::IsRunningOnChromeOS())
+      return encrypted_token_hex;
+
+    if (!LoadSystemSaltKey()) {
+      LOG(WARNING) << "System salt key is not available for decrypt.";
+      return std::string();
+    }
+    return DecryptTokenWithKey(system_salt_key_.get(),
+                               GetSystemSalt(),
+                               encrypted_token_hex);
+  }
+
  private:
   void LoadSystemSalt() {
     if (!system_salt_.empty())
       return;
     DBusThreadManager::Get()->GetCryptohomeClient()->
         GetSystemSalt(&system_salt_);
     CHECK(!system_salt_.empty());
     CHECK_EQ(system_salt_.size() % 2, 0U);
   }
 
+  // TODO: should this use the system salt for both the password and the salt
+  // value, or should this use a separate salt value?
+  bool LoadSystemSaltKey() {
+    if (!system_salt_key_.get())
+      system_salt_key_.reset(PassphraseToKey(GetSystemSalt(), GetSystemSalt()));
+    return system_salt_key_.get();
+  }
+
+  crypto::SymmetricKey* PassphraseToKey(const std::string& passprhase,

[Ryan Sleevi, 2013/04/26 18:38:20]

typo: passprhase -> passphrase

+                                        const std::string& salt) {
+    return crypto::SymmetricKey::DeriveKeyFromPassword(
+        crypto::SymmetricKey::AES, passprhase, salt, 1000, 256);
+  }
+
+
+  // Encrypts (AES) the token given |key| and |salt|.
+  std::string EncryptTokenWithKey(crypto::SymmetricKey* key,
+                                  const std::string& salt,
+                                  const std::string& token) {
+    crypto::Encryptor encryptor;
+    if (!encryptor.Init(key, crypto::Encryptor::CTR, std::string())) {
+      LOG(WARNING) << "Failed to initialize Encryptor.";
+      return std::string();
+    }
+    std::string nonce = salt.substr(0, kKeySize);
+    std::string encoded_token;
+    CHECK(encryptor.SetCounter(nonce));
+    if (!encryptor.Encrypt(token, &encoded_token)) {
+      LOG(WARNING) << "Failed to encrypt token.";
+      return std::string();
+    }
+
+    return StringToLowerASCII(base::HexEncode(
+        reinterpret_cast<const void*>(encoded_token.data()),
+        encoded_token.size()));
+  }
+
+  // Decrypts (AES) hex encoded encrypted token given |key| and |salt|.
+  std::string DecryptTokenWithKey(crypto::SymmetricKey* key,
+                                  const std::string& salt,
+                                  const std::string& encrypted_token_hex) {
+    std::vector<uint8> encrypted_token_bytes;
+    if (!base::HexStringToBytes(encrypted_token_hex, &encrypted_token_bytes)) {
+      LOG(WARNING) << "Corrupt encrypted token found.";
+      return std::string();
+    }
+
+    std::string encrypted_token(
+        reinterpret_cast<char*>(encrypted_token_bytes.data()),
+        encrypted_token_bytes.size());
+    crypto::Encryptor encryptor;
+    if (!encryptor.Init(key, crypto::Encryptor::CTR, std::string())) {
+      LOG(WARNING) << "Failed to initialize Encryptor.";
+      return std::string();
+    }
+
+    std::string nonce = salt.substr(0, kKeySize);
+    std::string token;
+    CHECK(encryptor.SetCounter(nonce));
+    if (!encryptor.Decrypt(encrypted_token, &token)) {
+      LOG(WARNING) << "Failed to decrypt token.";
+      return std::string();
+    }
+    return token;
+  }
+
   base::WeakPtrFactory<CryptohomeLibraryImpl> weak_ptr_factory_;
   std::vector<uint8> system_salt_;
+  // A key based on the system salt.  Useful for encrypting device-level
+  // data for which we have no additional credentials.
+  scoped_ptr<crypto::SymmetricKey> system_salt_key_;
 
   DISALLOW_COPY_AND_ASSIGN(CryptohomeLibraryImpl);
 };
 
 class CryptohomeLibraryStubImpl : public CryptohomeLibrary {
  public:
   CryptohomeLibraryStubImpl()
     : locked_(false) {}
   virtual ~CryptohomeLibraryStubImpl() {}
 
@@ skipping 38 matching lines @@
   }
 
   virtual bool InstallAttributesIsFirstInstall() OVERRIDE {
     return !locked_;
   }
 
   virtual std::string GetSystemSalt() OVERRIDE {
     return kStubSystemSalt;
   }
 
+  virtual std::string EncryptWithSystemSalt(const std::string& token) {
+    return token;
+  }
+
+  virtual std::string DecryptWithSystemSalt(
+      const std::string& encrypted_token_hex) {
+    return encrypted_token_hex;
+  }
+
  private:
   std::map<std::string, std::string> install_attrs_;
   bool locked_;
   DISALLOW_COPY_AND_ASSIGN(CryptohomeLibraryStubImpl);
 };
 
 CryptohomeLibrary::CryptohomeLibrary() {}
 CryptohomeLibrary::~CryptohomeLibrary() {}
 
+static CryptohomeLibrary* g_cryptohome_library = NULL;
+static CryptohomeLibrary* g_test_cryptohome_library = NULL;
+
 // static
-CryptohomeLibrary* CryptohomeLibrary::GetImpl(bool stub) {
-  CryptohomeLibrary* impl;
-  if (stub)
-    impl = new CryptohomeLibraryStubImpl();
+void CryptohomeLibrary::Initialize() {
+  CHECK(!g_cryptohome_library);
+  if (base::chromeos::IsRunningOnChromeOS())
+    g_cryptohome_library = new CryptohomeLibraryStubImpl();
   else
-    impl = new CryptohomeLibraryImpl();
-  return impl;
+    g_cryptohome_library = new CryptohomeLibraryImpl();
+}
+
+// static
+bool CryptohomeLibrary::IsInitialized() {
+  return g_cryptohome_library;
+}
+
+// static
+void CryptohomeLibrary::Shutdown() {
+  CHECK(g_cryptohome_library);
+  delete g_cryptohome_library;
+  g_cryptohome_library = NULL;
+}
+
+// static
+CryptohomeLibrary* CryptohomeLibrary::Get() {
+  CHECK(g_cryptohome_library || g_test_cryptohome_library)
+      << "CryptohomeLibrary::Get() called before Initialize()";
+  if (g_test_cryptohome_library)
+    return g_test_cryptohome_library;
+  return g_cryptohome_library;
+}
+
+// static
+void CryptohomeLibrary::SetForTest(CryptohomeLibrary* impl) {
+  CHECK(!g_test_cryptohome_library || !impl);
+  g_test_cryptohome_library = impl;
+}
+
+// static
+CryptohomeLibrary* CryptohomeLibrary::GetTestImpl() {
+  return new CryptohomeLibraryStubImpl();
 }
 
 } // namespace chromeos