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Ombi/Ombi.Helpers/PasswordHasher.cs

72 lines
3.0 KiB

8 years ago
#region Copyright
// /************************************************************************
// Copyright (c) 2016 Jamie Rees
// File: PasswordHasher.cs
// Created By: Jamie Rees
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
// ************************************************************************/
#endregion
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using System.Collections.Generic;
using System.Security.Cryptography;
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namespace Ombi.Helpers
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{
public static class PasswordHasher
{
// 24 = 192 bits
private const int SaltByteSize = 24;
private const int HashByteSize = 24;
private const int HasingIterationsCount = 10101;
public static byte[] ComputeHash(string password, byte[] salt, int iterations = HasingIterationsCount, int hashByteSize = HashByteSize)
{
var hashGenerator = new Rfc2898DeriveBytes(password, salt) { IterationCount = iterations };
return hashGenerator.GetBytes(hashByteSize);
}
public static byte[] GenerateSalt(int saltByteSize = SaltByteSize)
{
var saltGenerator = new RNGCryptoServiceProvider();
var salt = new byte[saltByteSize];
saltGenerator.GetBytes(salt);
return salt;
}
public static bool VerifyPassword(string password, byte[] passwordSalt, byte[] passwordHash)
{
var computedHash = ComputeHash(password, passwordSalt);
return AreHashesEqual(computedHash, passwordHash);
}
//Length constant verification - prevents timing attack
private static bool AreHashesEqual(IReadOnlyList<byte> firstHash, IReadOnlyList<byte> secondHash)
{
var minHashLength = firstHash.Count <= secondHash.Count ? firstHash.Count : secondHash.Count;
var xor = firstHash.Count ^ secondHash.Count;
for (var i = 0; i < minHashLength; i++)
xor |= firstHash[i] ^ secondHash[i];
return 0 == xor;
}
}
}