mirror of
https://github.com/moparisthebest/keepass2android
synced 2024-11-22 09:12:17 -05:00
Code updates from Ben Rush with Comments by Philipp
This commit is contained in:
Philipp Crocoll
parent
2cb6c79f0c
commit
8c15b38036
205
src/keepass2android/ChallengeInfo.cs
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205
src/keepass2android/ChallengeInfo.cs
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//
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// ChallengeInfo.cs
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//
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// Author:
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// Ben.Rush <>
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//
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// Copyright (c) 2014 Ben.Rush
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//
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using System;
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using System.Xml;
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using System.IO;
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using keepass2android;
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using KeePassLib.Serialization;
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using System.Xml.Serialization;
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namespace KeeChallenge
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{
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public class ChallengeInfo
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{
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public byte[] EncryptedSecret {
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get;
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private set;
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}
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public byte[] IV {
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get;
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private set;
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}
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public byte[] Challenge {
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get;
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private set;
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}
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public byte[] Verification {
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get;
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private set;
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}
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private ChallengeInfo()
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{
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}
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public ChallengeInfo(byte[] encryptedSecret, byte[] iv, byte[] challenge, byte[] verification)
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{
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EncryptedSecret = encryptedSecret;
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IV = iv;
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Challenge = challenge;
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Verification = verification;
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}
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public static ChallengeInfo Load(IOConnectionInfo ioc)
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{
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Stream sIn = null;
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ChallengeInfo inf = new ChallengeInfo();
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try
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{
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sIn = App.Kp2a.GetOtpAuxFileStorage(ioc).OpenFileForRead(ioc);
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XmlSerializer xs = new XmlSerializer(typeof (ChallengeInfo));
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if (!inf.LoadStream(sIn)) return null;
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}
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catch (Exception e)
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{
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Kp2aLog.Log(e.ToString());
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}
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finally
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{
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if(sIn != null) sIn.Close();
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}
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return inf;
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}
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private bool LoadStream(Stream AuxFile)
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{
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//read file
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XmlReader xml;
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try
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{
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XmlReaderSettings settings = new XmlReaderSettings();
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settings.CloseInput = true;
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xml = XmlReader.Create(AuxFile,settings);
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}
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catch (Exception)
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{
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return false;
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}
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try
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{
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while (xml.Read())
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{
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if (xml.IsStartElement())
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{
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switch (xml.Name)
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{
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case "encrypted":
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xml.Read();
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EncryptedSecret = Convert.FromBase64String(xml.Value.Trim());
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break;
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case "iv":
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xml.Read();
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IV = Convert.FromBase64String(xml.Value.Trim());
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break;
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case "challenge":
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xml.Read();
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Challenge = Convert.FromBase64String(xml.Value.Trim());
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break;
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case "verification":
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xml.Read();
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Verification = Convert.FromBase64String(xml.Value.Trim());
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break;
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}
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}
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}
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}
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catch (Exception)
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{
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return false;
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}
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xml.Close();
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//if failed, return false
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return true;
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}
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public bool Save(IOConnectionInfo ioc)
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{
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Stream sOut = null;
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try
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{
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using (var trans = App.Kp2a.GetOtpAuxFileStorage(ioc)
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.OpenWriteTransaction(ioc, App.Kp2a.GetBooleanPreference(PreferenceKey.UseFileTransactions)))
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{
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var stream = trans.OpenFile();
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if (SaveStream(sOut))
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{
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trans.CommitWrite();
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}
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else return false;
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}
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return true;
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}
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catch(Exception) { return false; }
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finally
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{
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if(sOut != null) sOut.Close();
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}
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return false;
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}
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private bool SaveStream(Stream file)
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{
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try
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{
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XmlWriterSettings settings = new XmlWriterSettings();
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settings.CloseOutput = true;
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settings.Indent = true;
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settings.IndentChars = "\t";
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settings.NewLineOnAttributes = true;
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XmlWriter xml = XmlWriter.Create(file,settings);
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xml.WriteStartDocument();
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xml.WriteStartElement("data");
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xml.WriteStartElement("aes");
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xml.WriteElementString("encrypted", Convert.ToBase64String(EncryptedSecret));
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xml.WriteElementString("iv", Convert.ToBase64String(IV));
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xml.WriteEndElement();
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xml.WriteElementString("challenge", Convert.ToBase64String(Challenge));
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xml.WriteElementString("verification", Convert.ToBase64String(Verification));
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xml.WriteEndElement();
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xml.WriteEndDocument();
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xml.Close();
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}
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catch (Exception)
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{
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return false;
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}
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return true;
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}
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}
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}
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196
src/keepass2android/KeeChallenge.cs
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196
src/keepass2android/KeeChallenge.cs
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@ -0,0 +1,196 @@
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/* KeeChallenge--Provides Yubikey challenge-response capability to Keepass
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* Copyright (C) 2014 Ben Rush
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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using System;
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using System.IO;
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using System.Collections.Generic;
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using System.Text;
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using System.Security.Cryptography;
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using System.Diagnostics;
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using System.Xml;
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using KeePassLib.Keys;
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using KeePassLib.Utility;
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using KeePassLib.Cryptography;
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using KeePassLib.Serialization;
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using keepass2android;
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using keepass2android.Io;
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namespace KeeChallenge
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{
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public sealed class KeeChallengeProv
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{
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private const string m_name = "Yubikey challenge-response";
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public static string Name { get { return m_name; } }
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public const int keyLenBytes = 20;
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public const int challengeLenBytes = 64;
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public const int responseLenBytes = 20;
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public const int secretLenBytes = 20;
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private KeeChallengeProv()
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{
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}
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private static byte[] GenerateChallenge()
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{
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CryptoRandom rand = CryptoRandom.Instance;
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return CryptoRandom.Instance.GetRandomBytes(challengeLenBytes);
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}
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private static byte[] GenerateResponse(byte[] challenge, byte[] key)
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{
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HMACSHA1 hmac = new HMACSHA1(key);
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byte[] resp = hmac.ComputeHash(challenge);
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hmac.Clear();
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return resp;
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}
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/// <summary>
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/// A method for generating encrypted ChallengeInfo to be saved. For security, this method should
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/// be called every time you get a successful challenge-response pair from the Yubikey. Failure to
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/// do so will permit password re-use attacks.
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/// </summary>
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/// <param name="secret">The un-encrypted secret</param>
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/// <returns>A fully populated ChallengeInfo object ready to be saved</returns>
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public static ChallengeInfo Encrypt(byte[] secret)
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{
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//generate a random challenge for use next time
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byte[] challenge = GenerateChallenge();
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//generate the expected HMAC-SHA1 response for the challenge based on the secret
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byte[] resp = GenerateResponse(challenge, secret);
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//use the response to encrypt the secret
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SHA256 sha = SHA256Managed.Create();
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byte[] key = sha.ComputeHash(resp); // get a 256 bit key from the 160 bit hmac response
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byte[] secretHash = sha.ComputeHash(secret);
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AesManaged aes = new AesManaged();
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aes.KeySize = key.Length * sizeof(byte) * 8; //pedantic, but foolproof
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aes.Key = key;
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aes.GenerateIV();
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aes.Padding = PaddingMode.PKCS7;
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byte[] iv = aes.IV;
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byte[] encrypted;
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ICryptoTransform enc = aes.CreateEncryptor();
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using (MemoryStream msEncrypt = new MemoryStream())
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{
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using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, enc, CryptoStreamMode.Write))
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{
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csEncrypt.Write(secret, 0, secret.Length);
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csEncrypt.FlushFinalBlock();
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encrypted = msEncrypt.ToArray();
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csEncrypt.Close();
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csEncrypt.Clear();
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}
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msEncrypt.Close();
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}
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ChallengeInfo inf = new ChallengeInfo (encrypted, aes.IV, challenge, secretHash);
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sha.Clear();
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aes.Clear();
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return inf;
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}
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private static bool DecryptSecret(byte[] yubiResp, ChallengeInfo inf, out byte[] secret)
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{
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secret = new byte[keyLenBytes];
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if (inf.IV == null) return false;
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if (inf.Verification == null) return false;
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//use the response to decrypt the secret
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SHA256 sha = SHA256Managed.Create();
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byte[] key = sha.ComputeHash(yubiResp); // get a 256 bit key from the 160 bit hmac response
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AesManaged aes = new AesManaged();
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aes.KeySize = key.Length * sizeof(byte) * 8; //pedantic, but foolproof
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aes.Key = key;
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aes.IV = inf.IV;
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aes.Padding = PaddingMode.PKCS7;
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ICryptoTransform dec = aes.CreateDecryptor();
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using (MemoryStream msDecrypt = new MemoryStream(inf.EncryptedSecret))
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{
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using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, dec, CryptoStreamMode.Read))
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{
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csDecrypt.Read(secret, 0, secret.Length);
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csDecrypt.Close();
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csDecrypt.Clear();
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}
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msDecrypt.Close();
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}
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byte[] secretHash = sha.ComputeHash(secret);
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for (int i = 0; i < secretHash.Length; i++)
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{
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if (secretHash[i] != inf.Verification[i])
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{
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//wrong response
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Array.Clear(secret, 0, secret.Length);
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return false;
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}
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}
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//return the secret
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sha.Clear();
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aes.Clear();
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return true;
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}
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/// <summary>
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/// The primary access point for challenge-response utility functions. Accepts a pre-populated ChallengeInfo object
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/// containing at least the IV, EncryptedSecret, and Verification fields. These fields are combined with the Yubikey response
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/// to decrypt and verify the secret.
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/// </summary>
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/// <param name="inf">A pre-populated object containing minimally the IV, EncryptedSecret and Verification fields.
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/// This should be populated from the database.xml auxilliary file</param>
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/// <param name="resp">The Yubikey's response to the issued challenge</param>
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/// <returns>The common secret, used as a composite key to encrypt a Keepass database</returns>
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public static byte[] GetSecret(ChallengeInfo inf, byte[] resp)
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{
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if (resp.Length != responseLenBytes)
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return null;
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if (inf == null)
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return null;
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if (inf.Challenge == null ||
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inf.Verification == null)
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return null;
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byte[] secret;
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if (DecryptSecret(resp, inf, out secret))
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{
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return secret;
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}
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else
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{
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return null;
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}
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}
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}
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}
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@ -84,7 +84,7 @@ namespace keepass2android
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private const int RequestCodePrepareDbFile = 1000;
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private const int RequestCodePrepareOtpAuxFile = 1001;
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private const int RequestCodePrepareChalAuxFile = 1001;
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private const int RequestCodeChallengeYubikey = 1002;
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private Task<MemoryStream> _loadDbTask;
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@ -144,7 +144,7 @@ namespace keepass2android
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public PasswordActivity()
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{
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_design = new ActivityDesign(this);
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_design = new ActivityDesign(this);
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}
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@ -277,19 +277,20 @@ namespace keepass2android
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if (_keyFileOrProvider == KeyProviderIdChallenge)
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{
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if (!LoadChalFile()) break;
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Intent chalIntent = new Intent(this, typeof(NfcChalActivity));
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Intent chalIntent = new Intent("com.yubichallenge.NFCActivity.CHALLENGE");
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chalIntent.PutExtra("challenge", _chalInfo.Challenge);
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StartActivityForResult(chalIntent, 0);
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chalIntent.PutExtra("slot", 2);
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IList<ResolveInfo> activities = PackageManager.QueryIntentActivities(chalIntent, 0);
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bool isIntentSafe = activities.Count > 0;
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if (isIntentSafe)
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StartActivityForResult(chalIntent, RequestCodeChallengeYubikey);
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} else {
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LoadOtpFile ();
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}
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}
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break;
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case NfcChalActivity.SUCCESS:
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_challengeResponse = data.GetByteArrayExtra("chalresp");
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break;
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break;
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}
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if (requestCode == RequestCodeChallengeYubikey && resultCode == Result.Ok) _challengeResponse = data.GetByteArrayExtra("response");
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}
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@ -331,7 +332,7 @@ namespace keepass2android
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private bool LoadChalFile()
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{
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//TODO make async!
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try
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{
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IFileStorage fileStorage = App.Kp2a.GetOtpAuxFileStorage(_ioConnection);
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@ -653,7 +654,7 @@ namespace keepass2android
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UpdateKeyProviderUiState();
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};
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FindViewById(Resource.Id.init_otp).Click += (sender, args) =>
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{
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{
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App.Kp2a.GetOtpAuxFileStorage(_ioConnection)
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.PrepareFileUsage(new FileStorageSetupInitiatorActivity(this, OnActivityResult, null), _ioConnection,
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RequestCodePrepareOtpAuxFile, false);
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@ -764,7 +765,6 @@ namespace keepass2android
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}
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UpdateOkButtonState();
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}
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private void PerformLoadDatabase()
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{
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