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How to call VFP function from .NET C# code?
Message
De
05/01/2015 04:06:29
 
 
Information générale
Forum:
ASP.NET
Catégorie:
Autre
Versions des environnements
Environment:
VB 9.0
OS:
Windows Server 2012
Network:
Windows 2008 Server
Database:
MS SQL Server
Application:
Web
Divers
Thread ID:
01612997
Message ID:
01613044
Vues:
65
>>>>>>>>If all this function does is encrypt a password there are lots of examples written in c# out there ( Google is your friend )
>>>>>>>
>>>>>>>I did but so for I could not find a simple enough c# encrypt function that can be "duplicated" in VFP. You see I need a function that would do the same from VFP and c# end.
>>>>>>>Thank you.
>>>>>>
>>>>>>Presumably you mean that the C# version should be usable with strings already encoded using the VFP cipher library that you mentioned?
>>>>>>
>>>>>>Al's pointer to Rick's paper is still valid - you could create a small VFP com interop which could be accessed from .net.
>>>>>>
>>>>>>But which functions of that library do you actually use ? - the core encryption is fairly straightforward.
>>>>>>I took a look at the original C code and it would seem that a C# version should be simple enough to implement......
>>>>>
>>>>>The function cipher() I am using in VFP code is written in VFP; not in C. Maybe Sergey also wrote it in C but the one he recommended to me years ago was the VFP function. To be honest, I don't even understand all VFP functions he used in creating the cipher(). So converting/rewriting it to C# would be a great challenge.
>>>>
>>>>The VFP code was based on a C conversion and there's a link to the C source - you might find that easier to convert to C# (or not :-} )
>>>
>>>Do you know where I can find the DLL (I presume tha the C code was built into a DLL) file that uses this C code? And maybe it has the C code there as well.
>>
>>Does this work (not properly tested and could certainly be improved):
using System;
>>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.ASCII.GetBytes(tcStr);
>>            int tcStrLength = tcStrBytes.Length;
>>
>>            string lcPassword = tcPassword + '0';
>>            byte[] lcPasswordBytes = Encoding.ASCII.GetBytes(lcPassword);
>>            int lnPassLen = lcPasswordBytes.Length - 1;
>>
>>            int lnPassPos = 0;
>> 
>>            string lcStrOut = string.Empty;
>>
>>            int lnPassNum = ((CipherGetPnum(lcPassword)/997 - 1)%254) + 1;
>>            
>>            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]);
>>                lnByte = lnByte & 0xFF;
>>                lcStrOut = lcStrOut + (lnByte == 0 ? Convert.ToChar( tcStrBytes[i + 1]) : Convert.ToChar(lnByte));
>>                lnPassPos = lnPassPos>=lnPassLen ? 1:lnPassPos + 1;
>>            }
>>            return lcStrOut;
>>        }
>>
>>        private int CipherGetPnum(string tcStr)
>>        {
>>            byte[] ascii = Encoding.ASCII.GetBytes(tcStr);
>>            int liRet = 1 + ascii.Select((t, i) => t + i).Sum();
>>
>>            while (liRet < PwMinNum)
>>            {
>>                liRet = liRet << 1;
>>            }
>>            return liRet;
>>        }
>>    }
>>}
>
>Thank you for the code. As I just mentioned in my reply to myself that I found the code that I did about 6 months ago. I will compare my code to your code. I take my hat off to you as you have done it in less than an hour and I remember it took me at least 2 days to write my C# code (and million of Google searches). Thank you!

Think I've got one error in there. Should be:
lnPassPos = lnPassPos>=lnPassLen ? 0:lnPassPos + 1;
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