D'une manière méthodes de cryptage

Fondamentalement, vous voulez utiliser MD5 ou SHA-256. Oh, et pour info, si c'est un moyen, il est appelé un de hachage. La documentation MSDN couvre à la fois les hachages largement.

Pour tous les nouveaux visiteurs à cette question, crackstation.net a plein .NET de la mise en œuvre en bas, avec plutôt une explication détaillée de ce que vous devez faire et comment tout cela fonctionne

Le code suivant est copié sans modification de crackstation.net

/* 
* Password Hashing With PBKDF2 (http://crackstation.net/hashing-security.htm).
* Copyright (c) 2013, Taylor Hornby
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without 
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, 
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation 
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
* POSSIBILITY OF SUCH DAMAGE.
*/
using System;
using System.Text;
using System.Security.Cryptography;
namespace PasswordHash
{
///<summary>
///Salted password hashing with PBKDF2-SHA1.
///Author: havoc AT defuse.ca
///www: http://crackstation.net/hashing-security.htm
///Compatibility: .NET 3.0 and later.
///</summary>
public class PasswordHash
{
//The following constants may be changed without breaking existing hashes.
public const int SALT_BYTE_SIZE = 24;
public const int HASH_BYTE_SIZE = 24;
public const int PBKDF2_ITERATIONS = 1000;
public const int ITERATION_INDEX = 0;
public const int SALT_INDEX = 1;
public const int PBKDF2_INDEX = 2;
///<summary>
///Creates a salted PBKDF2 hash of the password.
///</summary>
///<param name="password">The password to hash.</param>
///<returns>The hash of the password.</returns>
public static string CreateHash(string password)
{
//Generate a random salt
RNGCryptoServiceProvider csprng = new RNGCryptoServiceProvider();
byte[] salt = new byte[SALT_BYTE_SIZE];
csprng.GetBytes(salt);
//Hash the password and encode the parameters
byte[] hash = PBKDF2(password, salt, PBKDF2_ITERATIONS, HASH_BYTE_SIZE);
return PBKDF2_ITERATIONS + ":" +
Convert.ToBase64String(salt) + ":" +
Convert.ToBase64String(hash);
}
///<summary>
///Validates a password given a hash of the correct one.
///</summary>
///<param name="password">The password to check.</param>
///<param name="correctHash">A hash of the correct password.</param>
///<returns>True if the password is correct. False otherwise.</returns>
public static bool ValidatePassword(string password, string correctHash)
{
//Extract the parameters from the hash
char[] delimiter = { ':' };
string[] split = correctHash.Split(delimiter);
int iterations = Int32.Parse(split[ITERATION_INDEX]);
byte[] salt = Convert.FromBase64String(split[SALT_INDEX]);
byte[] hash = Convert.FromBase64String(split[PBKDF2_INDEX]);
byte[] testHash = PBKDF2(password, salt, iterations, hash.Length);
return SlowEquals(hash, testHash);
}
///<summary>
///Compares two byte arrays in length-constant time. This comparison
///method is used so that password hashes cannot be extracted from
///on-line systems using a timing attack and then attacked off-line.
///</summary>
///<param name="a">The first byte array.</param>
///<param name="b">The second byte array.</param>
///<returns>True if both byte arrays are equal. False otherwise.</returns>
private static bool SlowEquals(byte[] a, byte[] b)
{
uint diff = (uint)a.Length ^ (uint)b.Length;
for (int i = 0; i < a.Length && i < b.Length; i++)
diff |= (uint)(a[i] ^ b[i]);
return diff == 0;
}
///<summary>
///Computes the PBKDF2-SHA1 hash of a password.
///</summary>
///<param name="password">The password to hash.</param>
///<param name="salt">The salt.</param>
///<param name="iterations">The PBKDF2 iteration count.</param>
///<param name="outputBytes">The length of the hash to generate, in bytes.</param>
///<returns>A hash of the password.</returns>
private static byte[] PBKDF2(string password, byte[] salt, int iterations, int outputBytes)
{
Rfc2898DeriveBytes pbkdf2 = new Rfc2898DeriveBytes(password, salt);
pbkdf2.IterationCount = iterations;
return pbkdf2.GetBytes(outputBytes);
}
}
}

Quelques choses à noter:

• Le post original et OWASP lignes directrices les deux suggèrent de renforcer le chiffrement à l'aide de l'algorithme HMAC
• Nombre d'itérations dans le ci-dessus la mise en œuvre est sans doute un peu faible. OWASP et cette réponse suggèrent une auto équilibrage de la charge de travail
• Sel de taille dans la mise en œuvre ci-dessus est fixé à 24, mais si je suis en train de lire cette réponse correctement, il ne devrait pas aller au-dessus de 20. Cela dit, je suis tout sauf un expert en cryptographie, donc je ne peux pas vraiment dire si cette affirmation est vraie ou fausse