DocSpace-client/common/ASC.Core.Common/Security/Crypto.cs

/*
 *
 * (c) Copyright Ascensio System Limited 2010-2018
 *
 * This program is freeware. You can redistribute it and/or modify it under the terms of the GNU 
 * General Public License (GPL) version 3 as published by the Free Software Foundation (https://www.gnu.org/copyleft/gpl.html). 
 * In accordance with Section 7(a) of the GNU GPL its Section 15 shall be amended to the effect that 
 * Ascensio System SIA expressly excludes the warranty of non-infringement of any third-party rights.
 *
 * THIS PROGRAM IS DISTRIBUTED WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE. For more details, see GNU GPL at https://www.gnu.org/copyleft/gpl.html
 *
 * You can contact Ascensio System SIA by email at sales@onlyoffice.com
 *
 * The interactive user interfaces in modified source and object code versions of ONLYOFFICE must display 
 * Appropriate Legal Notices, as required under Section 5 of the GNU GPL version 3.
 *
 * Pursuant to Section 7 § 3(b) of the GNU GPL you must retain the original ONLYOFFICE logo which contains 
 * relevant author attributions when distributing the software. If the display of the logo in its graphic 
 * form is not reasonably feasible for technical reasons, you must include the words "Powered by ONLYOFFICE" 
 * in every copy of the program you distribute. 
 * Pursuant to Section 7 § 3(e) we decline to grant you any rights under trademark law for use of our trademarks.
 *
*/


using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using ASC.Common.Security;

namespace ASC.Core
{
    public class Crypto
    {
        private static byte[] GetSK1(bool rewrite)
        {
            return GetSK(rewrite.GetType().Name.Length);
        }

        private static byte[] GetSK2(bool rewrite)
        {
            return GetSK(rewrite.GetType().Name.Length * 2);
        }

        private static byte[] GetSK(int seed)
        {
            var random = new AscRandom(seed);
            var randomKey = new byte[32];
            for (var i = 0; i < randomKey.Length; i++)
            {
                randomKey[i] = (byte)random.Next(byte.MaxValue);
            }
            return randomKey;
        }

        public static string GetV(string data, int keyno, bool reverse)
        {
            var hasher = Rijndael.Create();
            hasher.Key = keyno == 1 ? GetSK1(false) : GetSK2(false);
            hasher.IV = new byte[hasher.BlockSize >> 3];

            string result;
            if (reverse)
            {
                using (var ms = new MemoryStream())
                using (var ss = new CryptoStream(ms, hasher.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    var buffer = Encoding.Unicode.GetBytes(data);
                    ss.Write(buffer, 0, buffer.Length);
                    ss.FlushFinalBlock();
                    hasher.Clear();
                    result = Convert.ToBase64String(ms.ToArray());
                }
            }
            else
            {
                var bytes = Convert.FromBase64String(data);
                using (var ms = new MemoryStream(bytes))
                using (var ss = new CryptoStream(ms, hasher.CreateDecryptor(), CryptoStreamMode.Read))
                {
                    var buffer = new byte[bytes.Length];
                    var size = ss.Read(buffer, 0, buffer.Length);
                    hasher.Clear();
                    var newBuffer = new byte[size];
                    Array.Copy(buffer, newBuffer, size);
                    result = Encoding.Unicode.GetString(newBuffer);
                }
            }

            return result;
        }

        internal static byte[] GetV(byte[] data, int keyno, bool reverse)
        {
            var hasher = Rijndael.Create();
            hasher.Key = keyno == 1 ? GetSK1(false) : GetSK2(false);
            hasher.IV = new byte[hasher.BlockSize >> 3];

            byte[] result;
            if (reverse)
            {
                using (var ms = new MemoryStream())
                using (var ss = new CryptoStream(ms, hasher.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    var buffer = data;
                    ss.Write(buffer, 0, buffer.Length);
                    ss.FlushFinalBlock();
                    hasher.Clear();
                    result = ms.ToArray();
                }
            }
            else
            {
                var bytes = data;
                using (var ms = new MemoryStream(bytes))
                using (var ss = new CryptoStream(ms, hasher.CreateDecryptor(), CryptoStreamMode.Read))
                {
                    var buffer = new byte[bytes.Length];
                    var size = ss.Read(buffer, 0, buffer.Length);
                    hasher.Clear();
                    var newBuffer = new byte[size];
                    Array.Copy(buffer, newBuffer, size);
                    result = newBuffer;
                }
            }

            return result;
        }

        public static string GeneratePassword(int length)
        {
            const string noise = "1234567890mnbasdflkjqwerpoiqweyuvcxnzhdkqpsdk";
            var random = new AscRandom();
            var pwd = string.Empty;
            while (0 < length--) pwd += noise[random.Next(noise.Length)];
            return pwd;
        }
    }
}