1 // 2 // Copyright (C) 2012 The Android Open Source Project 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // http://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 // 16 17 #include "shill/crypto_des_cbc.h" 18 19 #include <rpc/des_crypt.h> 20 21 #include <base/files/file_util.h> 22 #include <base/strings/string_util.h> 23 #include <brillo/data_encoding.h> 24 25 using base::FilePath; 26 using std::string; 27 using std::vector; 28 29 namespace shill { 30 31 const unsigned int CryptoDESCBC::kBlockSize = 8; 32 const char CryptoDESCBC::kID[] = "des-cbc"; 33 const char CryptoDESCBC::kSentinel[] = "[ok]"; 34 const char CryptoDESCBC::kVersion2Prefix[] = "02:"; 35 36 CryptoDESCBC::CryptoDESCBC() {} 37 38 string CryptoDESCBC::GetID() { 39 return kID; 40 } 41 42 bool CryptoDESCBC::Encrypt(const string& plaintext, string* ciphertext) { 43 // Never encrypt. We'll fall back to rot47 which doesn't depend on 44 // the owner key which may change due to rotation. 45 return false; 46 } 47 48 bool CryptoDESCBC::Decrypt(const string& ciphertext, string* plaintext) { 49 CHECK_EQ(kBlockSize, key_.size()); 50 CHECK_EQ(kBlockSize, iv_.size()); 51 int version = 1; 52 string b64_ciphertext = ciphertext; 53 if (base::StartsWith(ciphertext, kVersion2Prefix, 54 base::CompareCase::SENSITIVE)) { 55 version = 2; 56 b64_ciphertext.erase(0, strlen(kVersion2Prefix)); 57 } 58 59 string decoded_data; 60 if (!brillo::data_encoding::Base64Decode(b64_ciphertext, &decoded_data)) { 61 LOG(ERROR) << "Unable to base64-decode DEC-CBC ciphertext."; 62 return false; 63 } 64 65 vector<char> data(decoded_data.c_str(), 66 decoded_data.c_str() + decoded_data.length()); 67 if (data.empty() || (data.size() % kBlockSize != 0)) { 68 LOG(ERROR) << "Invalid DES-CBC ciphertext size: " << data.size(); 69 return false; 70 } 71 72 // The IV is modified in place. 73 vector<char> iv = iv_; 74 int rv = 75 cbc_crypt(key_.data(), data.data(), data.size(), DES_DECRYPT, iv.data()); 76 if (DES_FAILED(rv)) { 77 LOG(ERROR) << "DES-CBC decryption failed."; 78 return false; 79 } 80 if (data.back() != '\0') { 81 LOG(ERROR) << "DEC-CBC decryption resulted in invalid plain text."; 82 return false; 83 } 84 string text = data.data(); 85 if (version == 2) { 86 if (!base::EndsWith(text, kSentinel, base::CompareCase::SENSITIVE)) { 87 LOG(ERROR) << "DES-CBC decrypted text missing sentinel -- bad key?"; 88 return false; 89 } 90 text.erase(text.size() - strlen(kSentinel), strlen(kSentinel)); 91 } 92 *plaintext = text; 93 return true; 94 } 95 96 bool CryptoDESCBC::LoadKeyMatter(const FilePath& path) { 97 key_.clear(); 98 iv_.clear(); 99 string matter; 100 // TODO(petkov): This mimics current flimflam behavior. Fix it so that it 101 // doesn't read the whole file. 102 if (!base::ReadFileToString(path, &matter)) { 103 LOG(ERROR) << "Unable to load key matter from " << path.value(); 104 return false; 105 } 106 if (matter.size() < 2 * kBlockSize) { 107 LOG(ERROR) << "Key matter data not enough " << matter.size() << " < " 108 << 2 * kBlockSize; 109 return false; 110 } 111 string::const_iterator matter_start = 112 matter.begin() + (matter.size() - 2 * kBlockSize); 113 key_.assign(matter_start + kBlockSize, matter_start + 2 * kBlockSize); 114 iv_.assign(matter_start, matter_start + kBlockSize); 115 return true; 116 } 117 118 } // namespace shill 119
