>>>>>>>>>>>I am testing your code and mine code and neither one works :). I am sure it is me. Here is how I test it, please let me know if this is the correct approach:
>>>>>>>>>>>

>>>>>>>>>>>string cTest1 = "ABC123";
>>>>>>>>>>>string cTest1Encr;
>>>>>>>>>>>string cTest1Decr;
>>>>>>>>>>>cTest1Encr = Encrypt( cTest1, "123abc");
>>>>>>>>>>>cTest1Decr = Encrypt( cTest1Encr, "123abc");
>>>>>>>>>>>

>>>>>>>>>>>
>>>>>>>>>>>Shouldn't cTest1Decr show "ABC123"?
>>>>>>>>>>
>>>>>>>>>>Aren't you encrypting the values instead of decrypting the 2nd?
>>>>>>>>>
>>>>>>>>>The second parameter is the password string. The first one is the value.
>>>>>>>>
>>>>>>>>Too late to play tonight - I'll get back to you in the morning (my morning :-} )
>>>>>>
>>>>>>Encoding problem when char values > 128. This should work. Didn't look at your code I'm afraid:

using System;
>>>>>>using System.Collections.Generic;
>>>>>>using System.Linq;
>>>>>>using System.Text;
>>>>>>
>>>>>>namespace Cipher
>>>>>>{
>>>>>>    public class Cipher
>>>>>>    {
>>>>>>        private const int PwMinNum = 1000;
>>>>>>
>>>>>>        public string Encrypt(string tcStr, string tcPassword)
>>>>>>        {
>>>>>>            byte[] tcStrBytes = Encoding. GetEncoding(1252).GetBytes(tcStr);
>>>>>>            int tcStrLength = tcStrBytes.Length;
>>>>>>
>>>>>>            string lcPassword = tcPassword + ((char) 0).ToString();
>>>>>>            byte[] lcPasswordBytes = Encoding.GetEncoding(1252).GetBytes(lcPassword);
>>>>>>
>>>>>>            int lnPassLen = lcPasswordBytes.Length;
>>>>>>            int lnPassPos = 0;
>>>>>>            int lnPassNum = ((CipherGetPnum(lcPasswordBytes)/997 - 1)%254) + 1;
>>>>>>
>>>>>>            byte[] bytes = new byte[tcStr.Length];
>>>>>>
>>>>>>            for (int i = 0; i < tcStrLength; i++)
>>>>>>            {
>>>>>>                int lnNum01 = ((lnPassNum + (i - tcStrLength)) - 1);
>>>>>>                lnPassNum = (Math.Abs(lnNum01)%254)*Math.Sign(lnNum01) + 1;
>>>>>>                var lnByte = tcStrBytes[i] ^ (lnPassNum ^ lcPasswordBytes[lnPassPos]);
>>>>>>                bytes[i] = lnByte==0 ? tcStrBytes[i] : (byte) (lnByte & 0xFF);
>>>>>>                lnPassPos = lnPassPos > lnPassLen ? 0 : lnPassPos + 1;
>>>>>>            }
>>>>>>            return Encoding.GetEncoding(1252).GetString(bytes);
>>>>>>        }
>>>>>>
>>>>>>        private int CipherGetPnum(IEnumerable<byte> ascii)
>>>>>>        {
>>>>>>            int liRet = 1 + ascii.Select((t, i) => t + i).Sum();
>>>>>>            while (liRet < PwMinNum)
>>>>>>            {
>>>>>>                liRet = liRet << 1;
>>>>>>            }
>>>>>>            return liRet;
>>>>>>        }
>>>>>>    }
>>>>>>}

>>>>>
>>>>>Thank you very much. Your code works; almost 100%. Except when a string that you are trying to encrypt has more than 2 spaces
>>>>>(e.g."ABC123 ", 3 spaces after '3'), it produces error. Btw, if the string has only 2 empty spaces, no error. E.g. "ABC123 " (two spaces after 3), no error.
>>>>
>>>>Duh. Can't count - I was exceeding password length :-{ .
>>>>Two changes should fix:

int lnPassLen = lcPasswordBytes.Length - 1;
>>>>//and
>>>>lnPassPos = lnPassPos == lnPassLen ? 0 : lnPassPos + 1;

>>>
>>>Can you please post the final version with all the corrections?
>>>
>>>Also, perhaps it will be nice to add to Downloads section here as well.
>>>
>>>Thanks again.
>>
>>Don't know if I kept a copy. Dmitry may have it ?
>
>Of course I have it. This code works very well. Thank you.

Perhaps, since I don't seem to have kept it, you could send it to Naomi ?