/*

This file is part of cpp-ethereum.

cpp-ethereum is free software: you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation, either version 3 of the License, or

(at your option) any later version.

cpp-ethereum is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.

*/

/** @file SecretStore.cpp

* @author Gav Wood <i@gavwood.com>

* @date 2014

*/

#include "SecretStore.h"

#include <thread>

#include <mutex>

#include <boost/filesystem.hpp>

#include <libdevcore/Log.h>

#include <libdevcore/Guards.h>

#include <libdevcore/SHA3.h>

#include <libdevcore/FileSystem.h>

#include <test/JsonSpiritHeaders.h>

using namespace std;

using namespace dev;

namespace js = json_spirit;

namespace fs = boost::filesystem;

SecretStore::SecretStore()

{

load();

}

SecretStore::~SecretStore()

{

}

bytes SecretStore::secret(h128 const& _uuid, function<std::string()> const& _pass) const

{

auto rit = m_cached.find(_uuid);

if (rit != m_cached.end())

return rit->second;

auto it = m_keys.find(_uuid);

if (it == m_keys.end())

return bytes();

bytes key = decrypt(it->second.first, _pass());

if (!key.empty())

m_cached[_uuid] = key;

return key;

}

h128 SecretStore::importSecret(bytes const& _s, std::string const& _pass)

{

h128 r = h128::random();

m_cached[r] = _s;

m_keys[r] = make_pair(encrypt(_s, _pass), std::string());

save();

return r;

}

void SecretStore::kill(h128 const& _uuid)

{

m_cached.erase(_uuid);

if (m_keys.count(_uuid))

{

boost::filesystem::remove(m_keys[_uuid].second);

m_keys.erase(_uuid);

}

}

void SecretStore::clearCache() const

{

m_cached.clear();

}

void SecretStore::save(std::string const& _keysPath)

{

fs::path p(_keysPath);

boost::filesystem::create_directories(p);

for (auto& k: m_keys)

{

std::string uuid = toUUID(k.first);

std::string filename = (p / uuid).string() + ".json";

js::mObject v;

js::mValue crypto;

js::read_string(k.second.first, crypto);

v["crypto"] = crypto;

v["id"] = uuid;

v["version"] = 2;

writeFile(filename, js::write_string(js::mValue(v), true));

if (!k.second.second.empty() && k.second.second != filename)

boost::filesystem::remove(k.second.second);

k.second.second = filename;

}

}

void SecretStore::load(std::string const& _keysPath)

{

fs::path p(_keysPath);

boost::filesystem::create_directories(p);

js::mValue v;

for (fs::directory_iterator it(p); it != fs::directory_iterator(); ++it)

if (is_regular_file(it->path()))

{

cdebug << "Reading" << it->path();

js::read_string(contentsString(it->path().string()), v);

if (v.type() == js::obj_type)

{

js::mObject o = v.get_obj();

int version = o.count("Version") ? stoi(o["Version"].get_str()) : o.count("version") ? o["version"].get_int() : 0;

if (version == 2)

m_keys[fromUUID(o["id"].get_str())] = make_pair(js::write_string(o["crypto"], false), it->path().string());

else

cwarn << "Cannot read key version" << version;

}

// else

// cwarn << "Invalid JSON in key file" << it->path().string();

}

}

std::string SecretStore::encrypt(bytes const& _v, std::string const& _pass)

{

js::mObject ret;

// KDF info

unsigned dklen = 16;

unsigned iterations = 262144;

bytes salt = h256::random().asBytes();

ret["kdf"] = "pbkdf2";

{

js::mObject params;

params["prf"] = "hmac-sha256";

params["c"] = (int)iterations;

params["salt"] = toHex(salt);

params["dklen"] = (int)dklen;

ret["kdfparams"] = params;

}

bytes derivedKey = pbkdf2(_pass, salt, iterations, dklen);

// cipher info

ret["cipher"] = "aes-128-cbc";

h128 key(sha3(h128(derivedKey, h128::AlignRight)), h128::AlignRight);

h128 iv = h128::random();

{

js::mObject params;

params["iv"] = toHex(iv.ref());

ret["cipherparams"] = params;

}

// cipher text

bytes cipherText = encryptSymNoAuth(key, iv, &_v);

ret["ciphertext"] = toHex(cipherText);

// and mac.

h256 mac = sha3(bytesConstRef(&derivedKey).cropped(derivedKey.size() - 16).toBytes() + cipherText);

ret["mac"] = toHex(mac.ref());

return js::write_string((js::mValue)ret, true);

}

bytes SecretStore::decrypt(std::string const& _v, std::string const& _pass)

{

js::mObject o;

{

js::mValue ov;

js::read_string(_v, ov);

o = ov.get_obj();

}

// derive key

bytes derivedKey;

if (o["kdf"].get_str() == "pbkdf2")

{

auto params = o["kdfparams"].get_obj();

if (params["prf"].get_str() != "hmac-sha256")

{

cwarn << "Unknown PRF for PBKDF2" << params["prf"].get_str() << "not supported.";

return bytes();

}

unsigned iterations = params["c"].get_int();

bytes salt = fromHex(params["salt"].get_str());

derivedKey = pbkdf2(_pass, salt, iterations, params["dklen"].get_int());

}

else

{

cwarn << "Unknown KDF" << o["kdf"].get_str() << "not supported.";

return bytes();

}

bytes cipherText = fromHex(o["ciphertext"].get_str());

// check MAC

h256 mac(o["mac"].get_str());

h256 macExp = sha3(bytesConstRef(&derivedKey).cropped(derivedKey.size() - 16).toBytes() + cipherText);

if (mac != macExp)

{

cwarn << "Invalid key - MAC mismatch; expected" << toString(macExp) << ", got" << toString(mac);

return bytes();

}

// decrypt

if (o["cipher"].get_str() == "aes-128-cbc")

{

auto params = o["cipherparams"].get_obj();

h128 key(sha3(h128(derivedKey, h128::AlignRight)), h128::AlignRight);

h128 iv(params["iv"].get_str());

return decryptSymNoAuth(key, iv, &cipherText);

}

else

{

cwarn << "Unknown cipher" << o["cipher"].get_str() << "not supported.";

return bytes();

}

}