SecretStore.cpp

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/*
    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/>.
*/
#include "SecretStore.h"
#include <thread>
#include <mutex>
#include <boost/algorithm/string.hpp>
#include <boost/filesystem.hpp>
#include <libdevcore/Log.h>
#include <libdevcore/Guards.h>
#include <libdevcore/SHA3.h>
#include <libdevcore/FileSystem.h>
#include <libdevcore/JsonSpiritHeaders.h>
#include <libdevcrypto/Exceptions.h>
using namespace std;
using namespace dev;
namespace js = json_spirit;
namespace fs = boost::filesystem;

static const int c_keyFileVersion = 3;

static js::mValue upgraded(string const& _s)
{
    js::mValue v;
    js::read_string(_s, v);
    if (v.type() != js::obj_type)
        return js::mValue();
    js::mObject ret = v.get_obj();
    unsigned version = ret.count("Version") ? stoi(ret["Version"].get_str()) : ret.count("version") ? ret["version"].get_int() : 0;
    if (version == 1)
    {
        // upgrade to version 2
        js::mObject old;
        swap(old, ret);

        ret["id"] = old["Id"];
        js::mObject c;
        c["ciphertext"] = old["Crypto"].get_obj()["CipherText"];
        c["cipher"] = "aes-128-cbc";
        {
            js::mObject cp;
            cp["iv"] = old["Crypto"].get_obj()["IV"];
            c["cipherparams"] = cp;
        }
        c["kdf"] = old["Crypto"].get_obj()["KeyHeader"].get_obj()["Kdf"];
        {
            js::mObject kp;
            kp["salt"] = old["Crypto"].get_obj()["Salt"];
            for (auto const& i: old["Crypto"].get_obj()["KeyHeader"].get_obj()["KdfParams"].get_obj())
                if (i.first != "SaltLen")
                    kp[boost::to_lower_copy(i.first)] = i.second;
            c["kdfparams"] = kp;
        }
        c["sillymac"] = old["Crypto"].get_obj()["MAC"];
        c["sillymacjson"] = _s;
        ret["crypto"] = c;
        version = 2;
    }
    if (ret.count("Crypto") && !ret.count("crypto"))
    {
        ret["crypto"] = ret["Crypto"];
        ret.erase("Crypto");
    }
    if (version == 2)
    {
        ret["crypto"].get_obj()["cipher"] = "aes-128-ctr";
        ret["crypto"].get_obj()["compat"] = "2";
        version = 3;
    }
    if (version == c_keyFileVersion)
        return ret;
    return js::mValue();
}

SecretStore::SecretStore(fs::path const& _path): m_path(_path)
{
    load();
}

void SecretStore::setPath(fs::path const& _path)
{
    m_path = _path;
    load();
}

bytesSec SecretStore::secret(h128 const& _uuid, function<string()> const& _pass, bool _useCache) const
{
    auto rit = m_cached.find(_uuid);
    if (_useCache && rit != m_cached.end())
        return rit->second;
    auto it = m_keys.find(_uuid);
    bytesSec key;
    if (it != m_keys.end())
    {
        key = bytesSec(decrypt(it->second.encryptedKey, _pass()));
        if (!key.empty())
        {
            m_cached[_uuid] = key;
            // TODO: Fix constness.
            const_cast<SecretStore*>(this)->noteAddress(_uuid, toAddress(Secret{key}));
        }
    }
    return key;
}

bytesSec SecretStore::secret(Address const& _address, function<string()> const& _pass) const
{
    bytesSec ret;
    if (auto k = key(_address))
        ret = bytesSec(decrypt(k->second.encryptedKey, _pass()));
    return ret;
}

bytesSec SecretStore::secret(string const& _content, string const& _pass)
{
    try
    {
        js::mValue u = upgraded(_content);
        if (u.type() != js::obj_type)
            return bytesSec();
        return decrypt(js::write_string(u.get_obj()["crypto"], false), _pass);
    }
    catch (...)
    {
        return bytesSec();
    }
}

h128 SecretStore::importSecret(bytesSec const& _s, string const& _pass)
{
    h128 r = h128::random();
    EncryptedKey key{encrypt(_s.ref(), _pass), toUUID(r), KeyPair(Secret(_s)).address()};
    m_cached[r] = _s;
    m_keys[r] = move(key);
    save();
    return r;
}

h128 SecretStore::importSecret(bytesConstRef _s, string const& _pass)
{
    h128 r = h128::random();
    EncryptedKey key{encrypt(_s, _pass), toUUID(r), KeyPair(Secret(_s)).address()};
    m_cached[r] = bytesSec(_s);
    m_keys[r] = move(key);
    save();
    return r;
}

void SecretStore::kill(h128 const& _uuid)
{
    m_cached.erase(_uuid);
    if (m_keys.count(_uuid))
    {
        fs::remove(m_keys[_uuid].filename);
        m_keys.erase(_uuid);
    }
}

void SecretStore::clearCache() const
{
    m_cached.clear();
}

void SecretStore::save(fs::path const& _keysPath)
{
    fs::create_directories(_keysPath);
    DEV_IGNORE_EXCEPTIONS(fs::permissions(_keysPath, fs::owner_all));
    for (auto& k: m_keys)
    {
        string uuid = toUUID(k.first);
        fs::path filename = (_keysPath / uuid).string() + ".json";
        js::mObject v;
        js::mValue crypto;
        js::read_string(k.second.encryptedKey, crypto);
        v["address"] = k.second.address.hex();
        v["crypto"] = crypto;
        v["id"] = uuid;
        v["version"] = c_keyFileVersion;
        writeFile(filename, js::write_string(js::mValue(v), true));
        swap(k.second.filename, filename);
        if (!filename.empty() && !fs::equivalent(filename, k.second.filename))
            fs::remove(filename);
    }
}

bool SecretStore::noteAddress(h128 const& _uuid, Address const& _address)
{
    auto it = m_keys.find(_uuid);
    if (it != m_keys.end() && it->second.address == ZeroAddress)
    {
        it->second.address = _address;
        return true;
    }
    return false;
}

void SecretStore::load(fs::path const& _keysPath)
{
    try
    {
        for (fs::directory_iterator it(_keysPath); it != fs::directory_iterator(); ++it)
            if (fs::is_regular_file(it->path()))
                readKey(it->path().string(), true);
    }
    catch (...) {}
}

h128 SecretStore::readKey(fs::path const& _file, bool _takeFileOwnership)
{
    ctrace << "Reading" << _file.string();
    return readKeyContent(contentsString(_file), _takeFileOwnership ? _file : string());
}

h128 SecretStore::readKeyContent(string const& _content, fs::path const& _file)
{
    try
    {
        js::mValue u = upgraded(_content);
        if (u.type() == js::obj_type)
        {
            js::mObject& o = u.get_obj();
            auto uuid = fromUUID(o["id"].get_str());
            Address address = ZeroAddress;
            if (o.find("address") != o.end() && isHex(o["address"].get_str()))
                address = Address(o["address"].get_str());
            else
                cwarn << "Account address is either not defined or not in hex format" << _file.string();
            m_keys[uuid] = EncryptedKey{js::write_string(o["crypto"], false), _file, address};
            return uuid;
        }
        else
            cwarn << "Invalid JSON in key file" << _file.string();
        return h128();
    }
    catch (...)
    {
        return h128();
    }
}

bool SecretStore::recode(Address const& _address, string const& _newPass, function<string()> const& _pass, KDF _kdf)
{
    if (auto k = key(_address))
    {
        bytesSec s = secret(_address, _pass);
        if (s.empty())
            return false;
        else
        {
            k->second.encryptedKey = encrypt(s.ref(), _newPass, _kdf);
            save();
            return true;
        }
    }
    return false;
}

pair<h128 const, SecretStore::EncryptedKey> const* SecretStore::key(Address const& _address) const
{
    for (auto const& k: m_keys)
        if (k.second.address == _address)
            return &k;
    return nullptr;
}

pair<h128 const, SecretStore::EncryptedKey>* SecretStore::key(Address const& _address)
{
    for (auto& k: m_keys)
        if (k.second.address == _address)
            return &k;
    return nullptr;
}

bool SecretStore::recode(h128 const& _uuid, string const& _newPass, function<string()> const& _pass, KDF _kdf)
{
    bytesSec s = secret(_uuid, _pass, true);
    if (s.empty())
        return false;
    m_cached.erase(_uuid);
    m_keys[_uuid].encryptedKey = encrypt(s.ref(), _newPass, _kdf);
    save();
    return true;
}

static bytesSec deriveNewKey(string const& _pass, KDF _kdf, js::mObject& o_ret)
{
    unsigned dklen = 32;
    unsigned iterations = 1 << 18;
    bytes salt = h256::random().asBytes();
    if (_kdf == KDF::Scrypt)
    {
        unsigned p = 1;
        unsigned r = 8;
        o_ret["kdf"] = "scrypt";
        {
            js::mObject params;
            params["n"] = int64_t(iterations);
            params["r"] = int(r);
            params["p"] = int(p);
            params["dklen"] = int(dklen);
            params["salt"] = toHex(salt);
            o_ret["kdfparams"] = params;
        }
        return scrypt(_pass, salt, iterations, r, p, dklen);
    }
    else
    {
        o_ret["kdf"] = "pbkdf2";
        {
            js::mObject params;
            params["prf"] = "hmac-sha256";
            params["c"] = int(iterations);
            params["salt"] = toHex(salt);
            params["dklen"] = int(dklen);
            o_ret["kdfparams"] = params;
        }
        return pbkdf2(_pass, salt, iterations, dklen);
    }
}

string SecretStore::encrypt(bytesConstRef _v, string const& _pass, KDF _kdf)
{
    js::mObject ret;

    bytesSec derivedKey = deriveNewKey(_pass, _kdf, ret);
    if (derivedKey.empty())
        BOOST_THROW_EXCEPTION(crypto::CryptoException() << errinfo_comment("Key derivation failed."));

    ret["cipher"] = "aes-128-ctr";
    SecureFixedHash<16> key(derivedKey, h128::AlignLeft);
    h128 iv = h128::random();
    {
        js::mObject params;
        params["iv"] = toHex(iv.ref());
        ret["cipherparams"] = params;
    }

    // cipher text
    bytes cipherText = encryptSymNoAuth(key, iv, _v);
    if (cipherText.empty())
        BOOST_THROW_EXCEPTION(crypto::CryptoException() << errinfo_comment("Key encryption failed."));
    ret["ciphertext"] = toHex(cipherText);

    // and mac.
    h256 mac = sha3(derivedKey.ref().cropped(16, 16).toBytes() + cipherText);
    ret["mac"] = toHex(mac.ref());

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

bytesSec SecretStore::decrypt(string const& _v, string const& _pass)
{
    js::mObject o;
    {
        js::mValue ov;
        js::read_string(_v, ov);
        o = ov.get_obj();
    }

    // derive key
    bytesSec 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 bytesSec();
        }
        unsigned iterations = params["c"].get_int();
        bytes salt = fromHex(params["salt"].get_str());
        derivedKey = pbkdf2(_pass, salt, iterations, params["dklen"].get_int());
    }
    else if (o["kdf"].get_str() == "scrypt")
    {
        auto p = o["kdfparams"].get_obj();
        derivedKey = scrypt(_pass, fromHex(p["salt"].get_str()), p["n"].get_int(), p["r"].get_int(), p["p"].get_int(), p["dklen"].get_int());
    }
    else
    {
        cwarn << "Unknown KDF" << o["kdf"].get_str() << "not supported.";
        return bytesSec();
    }

    if (derivedKey.size() < 32 && !(o.count("compat") && o["compat"].get_str() == "2"))
    {
        cwarn << "Derived key's length too short (<32 bytes)";
        return bytesSec();
    }

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

    // check MAC
    if (o.count("mac"))
    {
        h256 mac(o["mac"].get_str());
        h256 macExp;
        if (o.count("compat") && o["compat"].get_str() == "2")
            macExp = sha3(derivedKey.ref().cropped(derivedKey.size() - 16).toBytes() + cipherText);
        else
            macExp = sha3(derivedKey.ref().cropped(16, 16).toBytes() + cipherText);
        if (mac != macExp)
        {
            cwarn << "Invalid key - MAC mismatch; expected" << toString(macExp) << ", got" << toString(mac);
            return bytesSec();
        }
    }
    else if (o.count("sillymac"))
    {
        h256 mac(o["sillymac"].get_str());
        h256 macExp = sha3(asBytes(o["sillymacjson"].get_str()) + derivedKey.ref().cropped(derivedKey.size() - 16).toBytes() + cipherText);
        if (mac != macExp)
        {
            cwarn << "Invalid key - MAC mismatch; expected" << toString(macExp) << ", got" << toString(mac);
            return bytesSec();
        }
    }
    else
        cwarn << "No MAC. Proceeding anyway.";

    // decrypt
    if (o["cipher"].get_str() == "aes-128-ctr")
    {
        auto params = o["cipherparams"].get_obj();
        h128 iv(params["iv"].get_str());
        if (o.count("compat") && o["compat"].get_str() == "2")
        {
            SecureFixedHash<16> key(sha3Secure(derivedKey.ref().cropped(derivedKey.size() - 16)), h128::AlignRight);
            return decryptSymNoAuth(key, iv, &cipherText);
        }
        else
            return decryptSymNoAuth(SecureFixedHash<16>(derivedKey, h128::AlignLeft), iv, &cipherText);
    }
    else
    {
        cwarn << "Unknown cipher" << o["cipher"].get_str() << "not supported.";
        return bytesSec();
    }
}