blob: 8c12a44ef9cb6fa11f6be0123a18e0fa0e09f099 [file] [log] [blame]
// Copyright (c) 2012 The Chromium OS 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 "shill/crypto_des_cbc.h"
#include <rpc/des_crypt.h>
#include <base/file_util.h>
#include <base/string_util.h>
#include "shill/glib.h"
using std::string;
using std::vector;
namespace shill {
const unsigned int CryptoDESCBC::kBlockSize = 8;
const char CryptoDESCBC::kID[] = "des-cbc";
const char CryptoDESCBC::kSentinel[] = "[ok]";
const char CryptoDESCBC::kVersion2Prefix[] = "02:";
CryptoDESCBC::CryptoDESCBC(GLib *glib) : glib_(glib) {}
string CryptoDESCBC::GetID() {
return kID;
}
bool CryptoDESCBC::Encrypt(const string &plaintext, string *ciphertext) {
// Never encrypt. We'll fall back to rot47 which doesn't depend on
// the owner key which may change due to rotation.
return false;
}
bool CryptoDESCBC::Decrypt(const string &ciphertext, string *plaintext) {
CHECK_EQ(kBlockSize, key_.size());
CHECK_EQ(kBlockSize, iv_.size());
int version = 1;
string b64_ciphertext = ciphertext;
if (StartsWithASCII(ciphertext, kVersion2Prefix, true)) {
version = 2;
b64_ciphertext.erase(0, strlen(kVersion2Prefix));
}
gsize data_len = 0;
guchar *gdata = glib_->Base64Decode(b64_ciphertext.c_str(), &data_len);
if (!gdata) {
LOG(ERROR) << "Unable to base64-decode DEC-CBC ciphertext.";
return false;
}
vector<char> data(gdata, gdata + data_len);
glib_->Free(gdata);
if (data.empty() || (data.size() % kBlockSize != 0)) {
LOG(ERROR) << "Invalid DES-CBC ciphertext size: " << data.size();
return false;
}
// The IV is modified in place.
vector<char> iv = iv_;
int rv =
cbc_crypt(key_.data(), data.data(), data.size(), DES_DECRYPT, iv.data());
if (DES_FAILED(rv)) {
LOG(ERROR) << "DES-CBC decryption failed.";
return false;
}
if (data.back() != '\0') {
LOG(ERROR) << "DEC-CBC decryption resulted in invalid plain text.";
return false;
}
string text = data.data();
if (version == 2) {
if (!EndsWith(text, kSentinel, true)) {
LOG(ERROR) << "DES-CBC decrypted text missing sentinel -- bad key?";
return false;
}
text.erase(text.size() - strlen(kSentinel), strlen(kSentinel));
}
*plaintext = text;
return true;
}
bool CryptoDESCBC::LoadKeyMatter(const FilePath &path) {
key_.clear();
iv_.clear();
string matter;
// TODO(petkov): This mimics current flimflam behavior. Fix it so that it
// doesn't read the whole file.
if (!file_util::ReadFileToString(path, &matter)) {
LOG(ERROR) << "Unable to load key matter from " << path.value();
return false;
}
if (matter.size() < 2 * kBlockSize) {
LOG(ERROR) << "Key matter data not enough " << matter.size() << " < "
<< 2 * kBlockSize;
return false;
}
string::const_iterator matter_start =
matter.begin() + (matter.size() - 2 * kBlockSize);
key_.assign(matter_start + kBlockSize, matter_start + 2 * kBlockSize);
iv_.assign(matter_start, matter_start + kBlockSize);
return true;
}
} // namespace shill