blob: 00ce22b7dcab310f51d7d3b5cc18e3318819647e [file] [log] [blame]
Darin Petkov823c47e2011-06-27 16:15:35 -07001// Copyright (c) 2011 The Chromium OS 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 "shill/crypto_des_cbc.h"
6
7#include <rpc/des_crypt.h>
8
9#include <base/file_util.h>
10#include <base/string_util.h>
11
12#include "shill/glib.h"
13
14using std::string;
15using std::vector;
16
17namespace shill {
18
19const int CryptoDESCBC::kBlockSize = 8;
20const char CryptoDESCBC::kID[] = "des-cbc";
21const char CryptoDESCBC::kSentinel[] = "[ok]";
22const char CryptoDESCBC::kVersion2Prefix[] = "02:";
23
24CryptoDESCBC::CryptoDESCBC(GLib *glib) : glib_(glib) {}
25
26string CryptoDESCBC::GetID() {
27 return kID;
28}
29
30bool CryptoDESCBC::Encrypt(const string &plaintext, string *ciphertext) {
31 CHECK_EQ(kBlockSize, key_.size());
32 CHECK_EQ(kBlockSize, iv_.size());
33
34 // Prepare the data to be encrypted by concatenating |plaintext| and
35 // |kSentinel|, and appending nulls to a size multiple of |kBlockSize|.
36 vector<char> data(plaintext.begin(), plaintext.end());
37 data.insert(data.end(), kSentinel, kSentinel + strlen(kSentinel));
38 // +1 to encrypt at least one null terminator. +(kBlockSize - 1) to pad to a
39 // full block, if necessary.
40 int blocks = (data.size() + 1 + (kBlockSize - 1)) / kBlockSize;
41 data.resize(blocks * kBlockSize, '\0');
42
43 // The IV is modified in place.
44 vector<char> iv = iv_;
45 int rv =
46 cbc_crypt(key_.data(), data.data(), data.size(), DES_ENCRYPT, iv.data());
47 if (DES_FAILED(rv)) {
48 LOG(ERROR) << "DES-CBC encryption failed.";
49 return false;
50 }
51 gchar *b64_ciphertext =
52 glib_->Base64Encode(reinterpret_cast<guchar *>(data.data()), data.size());
53 if (!b64_ciphertext) {
54 LOG(ERROR) << "Unable to base64-encode DES-CBC ciphertext.";
55 return false;
56 }
57 *ciphertext = string(kVersion2Prefix) + b64_ciphertext;
58 glib_->Free(b64_ciphertext);
59 return true;
60}
61
62bool CryptoDESCBC::Decrypt(const string &ciphertext, string *plaintext) {
63 CHECK_EQ(kBlockSize, key_.size());
64 CHECK_EQ(kBlockSize, iv_.size());
65 int version = 1;
66 string b64_ciphertext = ciphertext;
67 if (StartsWithASCII(ciphertext, kVersion2Prefix, true)) {
68 version = 2;
69 b64_ciphertext.erase(0, strlen(kVersion2Prefix));
70 }
71
72 gsize data_len = 0;
73 guchar *gdata = glib_->Base64Decode(b64_ciphertext.c_str(), &data_len);
74 if (!gdata) {
75 LOG(ERROR) << "Unable to base64-decode DEC-CBC ciphertext.";
76 return false;
77 }
78
79 vector<char> data(gdata, gdata + data_len);
80 glib_->Free(gdata);
81 if (data.empty() || (data.size() % kBlockSize != 0)) {
82 LOG(ERROR) << "Invalid DES-CBC ciphertext size: " << data.size();
83 return false;
84 }
85
86 // The IV is modified in place.
87 vector<char> iv = iv_;
88 int rv =
89 cbc_crypt(key_.data(), data.data(), data.size(), DES_DECRYPT, iv.data());
90 if (DES_FAILED(rv)) {
91 LOG(ERROR) << "DES-CBC decryption failed.";
92 return false;
93 }
94 if (data.back() != '\0') {
95 LOG(ERROR) << "DEC-CBC decryption resulted in invalid plain text.";
96 return false;
97 }
98 string text = data.data();
99 if (version == 2) {
100 if (!EndsWith(text, kSentinel, true)) {
101 LOG(ERROR) << "DES-CBC decrypted text missing sentinel -- bad key?";
102 return false;
103 }
104 text.erase(text.size() - strlen(kSentinel), strlen(kSentinel));
105 }
106 *plaintext = text;
107 return true;
108}
109
110bool CryptoDESCBC::LoadKeyMatter(const FilePath &path) {
111 key_.clear();
112 iv_.clear();
113 string matter;
114 // TODO(petkov): This mimics current flimflam behavior. Fix it so that it
115 // doesn't read the whole file.
116 if (!file_util::ReadFileToString(path, &matter)) {
117 LOG(ERROR) << "Unable to load key matter from " << path.value();
118 return false;
119 }
120 if (matter.size() < 2 * kBlockSize) {
121 LOG(ERROR) << "Key matter data not enough " << matter.size() << " < "
122 << 2 * kBlockSize;
123 return false;
124 }
125 string::const_iterator matter_start =
126 matter.begin() + (matter.size() - 2 * kBlockSize);
127 key_.assign(matter_start + kBlockSize, matter_start + 2 * kBlockSize);
128 iv_.assign(matter_start, matter_start + kBlockSize);
129 return true;
130}
131
132} // namespace shill