i already encrypt my password but when i log in it gives me an error. how can decrypte it

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C#

Can you tell me how can decrypte it

Posted 25-Oct-12 8:06am

Gilbertinino

Updated 25-Oct-12 8:10am

Nelek

v2

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Comments

Sergey Alexandrovich Kryukov 25-Oct-12 14:20pm

Why would you want it, ever? Wrong way!
--SA

3 solutions

Solution 2

In mysql you can use Query like select password from login_tb where binary username=+txt1.text;

Posted 25-Oct-12 18:49pm

Nagaraja1986

Solution 3

TRY THESE CODE:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.Data;
using System.Windows.Forms;
namespace Inventory_Accountancy
{
public class Cryptography
{
private static string _key;
 
public Cryptography() { }
public static string key { set { _key = value; } }
 
public static string Encrypt(string encrypt)
{
try
{
return Encrypt(encrypt, _key);
}
catch (Exception ex)
{
return "Wrong " + ex.Message.ToString();//,"Inventory Accountancy",MessageBoxButtons.OK,MessageBoxIcon.Error);
}
}
 
internal static string Encrypt(string encrypt, string strKey)
{
try
{
TripleDESCryptoServiceProvider objDESC = new TripleDESCryptoServiceProvider();
MD5CryptoServiceProvider objHashMD5 = new MD5CryptoServiceProvider();
byte[] byteHash, byteBuff;
 
byteHash = objHashMD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(strKey));
objHashMD5 = null;
objDESC.Key = byteHash;
objDESC.Mode = CipherMode.ECB;
 
byteBuff = ASCIIEncoding.ASCII.GetBytes(encrypt);
return Convert.ToBase64String(objDESC.CreateEncryptor().TransformFinalBlock(byteBuff, 0, byteBuff.Length));
}//objDESCrypto.CreateEncryptor().TransformFinalBlock(byteBuff, 0, byteBuff.Length)
catch (Exception ex)
{
return "Wrong " + ex.Message.ToString();
}
}
 
public static string Decrypt(string decrypt)
{
try
{
return Decrypt(decrypt, _key);
}
catch (Exception ex)
{
return "Wrong " + ex.Message.ToString();
}
}
 
public static string Decrypt(string decrypt, string strkey)
{
try
{
TripleDESCryptoServiceProvider objDESC = new TripleDESCryptoServiceProvider();
MD5CryptoServiceProvider objHashMD5 = new MD5CryptoServiceProvider();
byte[] byteHash, byteBuff;
string tempStrKey = strkey;
 
byteHash = objHashMD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(tempStrKey));
objHashMD5 = null;
objDESC.Key = byteHash;
objDESC.Mode = CipherMode.ECB;
 

byteBuff = Convert.FromBase64String(decrypt);
string strDecrypted = ASCIIEncoding.ASCII.GetString(objDESC.CreateDecryptor().TransformFinalBlock(byteBuff, 0, byteBuff.Length));
objDESC = null;
 
return strDecrypted;
}
catch (Exception ex)
{
return "Wrong " + ex.Message.ToString();
}
}
}
}

Posted 29-Mar-13 19:34pm

Mahesh_Bhosale

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Sergey Alexandrovich Kryukov · Accepted Answer · 2012-10-25T08:19:00

You should never ever decrypt a password. You should never develop a system where a password needs to be decrypted, or where a password needs to be stored, or where there is a possibility that any person can know a password created by a user. Such practices are unsafe and never needed. If you think about it, you will understand that the original password is absolutely not needed for authentication.

Disagree? Feel puzzled? Keep reading.

One of the ways of solving this problem which is usually used is calculation of a cryptographic hash function in both cases and storing the hash. If you want to say that this stored value is just the encrypted password, think again. The big difference is: the cryptographic hash cannot be decrypted at all, this is a one-way function. So, it's infeasible to calculate a password from hash (and, of course, it has nothing to do with system permissions: this is equally infeasible for anyone). And this is not needed: you just store hash and compare hash with hash.

Please see:
http://en.wikipedia.org/wiki/Cryptographic_hash_function[^],
http://en.wikipedia.org/wiki/Computational_complexity_theory#Intractability[^].

[EDIT]

The algorithms you need are already available in .NET:
http://msdn.microsoft.com/en-us/library/system.security.cryptography.hashalgorithm.aspx[^].

Don't use MD5 or SHA-1 — they are found to be broken; better use one from the SHA-2 family:
http://en.wikipedia.org/wiki/MD5[^],
http://en.wikipedia.org/wiki/SHA-1[^],
http://en.wikipedia.org/wiki/SHA-2[^].

[END EDIT]

Please see my past answers:
storing password value int sql server with secure way[^],
Decryption of Encrypted Password[^].

—SA