1 // Copyright (c) 2011 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 "chrome/browser/password_manager/encryptor.h"
6
7 #include "base/logging.h"
8 #include "base/memory/scoped_ptr.h"
9 #include "base/utf_string_conversions.h"
10 #include "crypto/encryptor.h"
11 #include "crypto/symmetric_key.h"
12
13 namespace {
14
15 // Salt for Symmetric key derivation.
16 const char kSalt[] = "saltysalt";
17
18 // Key size required for 128 bit AES.
19 const size_t kDerivedKeySizeInBits = 128;
20
21 // Constant for Symmetic key derivation.
22 const size_t kEncryptionIterations = 1;
23
24 // Size of initialization vector for AES 128-bit.
25 const size_t kIVBlockSizeAES128 = 16;
26
27 // Prefix for cypher text returned by obfuscation version. We prefix the
28 // cyphertext with this string so that future data migration can detect
29 // this and migrate to full encryption without data loss.
30 const char kObfuscationPrefix[] = "v10";
31
32 // Generates a newly allocated SymmetricKey object based a hard-coded password.
33 // Ownership of the key is passed to the caller. Returns NULL key if a key
34 // generation error occurs.
GetEncryptionKey()35 crypto::SymmetricKey* GetEncryptionKey() {
36 // We currently "obfuscate" by encrypting and decrypting with hard-coded
37 // password. We need to improve this password situation by moving a secure
38 // password into a system-level key store.
39 // http://crbug.com/25404 and http://crbug.com/49115
40 std::string password = "peanuts";
41 std::string salt(kSalt);
42
43 // Create an encryption key from our password and salt.
44 scoped_ptr<crypto::SymmetricKey> encryption_key(
45 crypto::SymmetricKey::DeriveKeyFromPassword(crypto::SymmetricKey::AES,
46 password,
47 salt,
48 kEncryptionIterations,
49 kDerivedKeySizeInBits));
50 DCHECK(encryption_key.get());
51
52 return encryption_key.release();
53 }
54
55 } // namespace
56
EncryptString16(const string16 & plaintext,std::string * ciphertext)57 bool Encryptor::EncryptString16(const string16& plaintext,
58 std::string* ciphertext) {
59 return EncryptString(UTF16ToUTF8(plaintext), ciphertext);
60 }
61
DecryptString16(const std::string & ciphertext,string16 * plaintext)62 bool Encryptor::DecryptString16(const std::string& ciphertext,
63 string16* plaintext) {
64 std::string utf8;
65 if (!DecryptString(ciphertext, &utf8))
66 return false;
67
68 *plaintext = UTF8ToUTF16(utf8);
69 return true;
70 }
71
EncryptString(const std::string & plaintext,std::string * ciphertext)72 bool Encryptor::EncryptString(const std::string& plaintext,
73 std::string* ciphertext) {
74 // This currently "obfuscates" by encrypting with hard-coded password.
75 // We need to improve this password situation by moving a secure password
76 // into a system-level key store.
77 // http://crbug.com/25404 and http://crbug.com/49115
78
79 if (plaintext.empty()) {
80 *ciphertext = std::string();
81 return true;
82 }
83
84 scoped_ptr<crypto::SymmetricKey> encryption_key(GetEncryptionKey());
85 if (!encryption_key.get())
86 return false;
87
88 std::string iv(kIVBlockSizeAES128, ' ');
89 crypto::Encryptor encryptor;
90 if (!encryptor.Init(encryption_key.get(), crypto::Encryptor::CBC, iv))
91 return false;
92
93 if (!encryptor.Encrypt(plaintext, ciphertext))
94 return false;
95
96 // Prefix the cypher text with version information.
97 ciphertext->insert(0, kObfuscationPrefix);
98 return true;
99 }
100
DecryptString(const std::string & ciphertext,std::string * plaintext)101 bool Encryptor::DecryptString(const std::string& ciphertext,
102 std::string* plaintext) {
103 // This currently "obfuscates" by encrypting with hard-coded password.
104 // We need to improve this password situation by moving a secure password
105 // into a system-level key store.
106 // http://crbug.com/25404 and http://crbug.com/49115
107
108 if (ciphertext.empty()) {
109 *plaintext = std::string();
110 return true;
111 }
112
113 // Check that the incoming cyphertext was indeed encrypted with the expected
114 // version. If the prefix is not found then we'll assume we're dealing with
115 // old data saved as clear text and we'll return it directly.
116 // Credit card numbers are current legacy data, so false match with prefix
117 // won't happen.
118 if (ciphertext.find(kObfuscationPrefix) != 0) {
119 *plaintext = ciphertext;
120 return true;
121 }
122
123 // Strip off the versioning prefix before decrypting.
124 std::string raw_ciphertext = ciphertext.substr(strlen(kObfuscationPrefix));
125
126 scoped_ptr<crypto::SymmetricKey> encryption_key(GetEncryptionKey());
127 if (!encryption_key.get())
128 return false;
129
130 std::string iv(kIVBlockSizeAES128, ' ');
131 crypto::Encryptor encryptor;
132 if (!encryptor.Init(encryption_key.get(), crypto::Encryptor::CBC, iv))
133 return false;
134
135 if (!encryptor.Decrypt(raw_ciphertext, plaintext))
136 return false;
137
138 return true;
139 }
140