Complete Password Hashing Solution using C# with Example



Complete Password Hashing Solution using C# with Example

Pbkdf2 
using System; 
using System.Linq; 
using System.Security.Cryptography; 
namespace YourCryptoNamespace 
{ 
///  
/// Salted password hashing with PBKDF2-SHA1. 
/// Compatibility: .NET 3.0 and later. 
///  
/// See http://crackstation.net/hashing-security.htm for much more on password 
hashing. 
public static class PasswordHashProvider 
 

{ 
///  
/// The salt byte size, 64 length ensures safety but could be increased / decreased 
///  
private const int SaltByteSize = 64; 
///  
/// The hash byte size, 
///  
private const int HashByteSize = 64; 
///  
/// High iteration count is less likely to be cracked 
///  
private const int Pbkdf2Iterations = 10000; 
///  
/// Creates a salted PBKDF2 hash of the password. 
///  
///   
/// The salt and the hash have to be persisted side by side for the password. They could be 
persisted as bytes or as a string using the convenience methods in the next class to convert from 
byte[] to string and later back again when executing password validation. 
///   
/// The password to hash. 
/// The hash of the password. 
public static PasswordHashContainer CreateHash(string password) 
{ 
// Generate a random salt 
using (var csprng = new RNGCryptoServiceProvider()) 
{ 
// create a unique salt for every password hash to prevent rainbow and dictionary based 
attacks 
var salt = new byte[SaltByteSize]; 
csprng.GetBytes(salt); 
// Hash the password and encode the parameters 
var hash = Pbkdf2(password, salt, Pbkdf2Iterations, HashByteSize); 
return new PasswordHashContainer(hash, salt); 
} 
} 
///  
/// Recreates a password hash based on the incoming password string and the stored salt 
///  
///  The  password  to  check. 
/// The salt existing. 
/// the generated hash based on the password and salt 
public static byte[] CreateHash(string password, byte[] salt) 
{ 
// Extract the parameters from the hash 
return Pbkdf2(password, salt, Pbkdf2Iterations, HashByteSize); 
} 
///  
/// Validates a password given a hash of the correct one. 
///  
///  The  password  to  check. 
/// The existing stored salt. 
/// The hash of the existing password. 
/// true if the password is correct. false otherwise.  
public static bool ValidatePassword(string password, byte[] salt, byte[] correctHash) 
{ 
// Extract the parameters from the hash 
 

byte[] testHash = Pbkdf2(password, salt, Pbkdf2Iterations, HashByteSize); 
return CompareHashes(correctHash, testHash); 
} 
///  
/// Compares two byte arrays (hashes) 
///  
/// The array1. 
/// The array2. 
/// true if they are the same, otherwise false 
public static bool CompareHashes(byte[] array1, byte[] array2) 
{ 
if (array1.Length != array2.Length) return false; 
return !array1.Where((t, i) => t != array2[i]).Any(); 
} 
///  
/// Computes the PBKDF2-SHA1 hash of a password. 
///  
/// The password to hash. 
/// The salt. 
/// The PBKDF2 iteration count. 
/// The length of the hash to generate, in bytes. 
/// A hash of the password. 
private static byte[] Pbkdf2(string password, byte[] salt, int iterations, int outputBytes) 
{ 
using (var pbkdf2 = new Rfc2898DeriveBytes(password, salt)) 
{ 
pbkdf2.IterationCount = iterations; 
return pbkdf2.GetBytes(outputBytes); 
} 
} 
} 
///  
/// Container for password hash and salt and iterations. 
///  
public sealed class PasswordHashContainer 
{ 
///  
/// Gets the hashed password. 
///  
public byte[] HashedPassword { get; private set; } 
///  
/// Gets the salt. 
///  
public byte[] Salt { get; private set; } 
///  
/// Initializes a new instance of the  class. 
///  
/// The hashed password. 
/// The salt. 
public PasswordHashContainer(byte[] hashedPassword, byte[] salt) 
{ 
this.HashedPassword = hashedPassword; 
this.Salt = salt; 
} 
} 
///  
/// Convenience methods for converting between hex strings and byte array. 
///  
 

public static class ByteConverter 
{ 
///  
/// Converts the hex representation string to an array of bytes 
///  
/// The hexed string. 
///  
public static byte[] GetHexBytes(string hexedString) 
{ 
var bytes = new byte[hexedString.Length / 2]; 
for (var i = 0; i < bytes.Length; i++) 
{ 
var strPos = i * 2; 
var chars = hexedString.Substring(strPos, 2); 
bytes[i] = Convert.ToByte(chars, 16); 
} 
return bytes; 
} 
///  
/// Gets a hex string representation of the byte array passed in. 
///  
/// The bytes. 
public static string GetHexString(byte[] bytes) 
{ 
return BitConverter.ToString(bytes).Replace("-", "").ToUpper(); 
} 
} 
} 
/* 
* 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. 
*/ 
Please see this excellent resource Crackstation - Salted Password Hashing - Doing it Right for more information. 
Part of this solution (the hashing function) was based on the code from that site. 
 

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