In .NET 6, you can use the `Rfc2898DeriveBytes` class from the `System.Security.Cryptography` namespace to generate a hash-based password with a salt. Here's an example of how you can do this:
using System;
using System.Security.Cryptography;
using System.Text;
public class PasswordHasher
{
private const int SaltSize = 16; // 128 bits
private const int HashSize = 32; // 256 bits
private const int Iterations = 10000;
public static string HashPassword(string password)
{
byte[] salt = new byte[SaltSize];
using (var rng = RandomNumberGenerator.Create())
{
rng.GetBytes(salt);
}
byte[] hash = HashPasswordWithSalt(password, salt);
// Combine the salt and hash
byte[] saltedHash = new byte[SaltSize + HashSize];
Buffer.BlockCopy(salt, 0, saltedHash, 0, SaltSize);
Buffer.BlockCopy(hash, 0, saltedHash, SaltSize, HashSize);
return Convert.ToBase64String(saltedHash);
}
public static bool VerifyPassword(string password, string hashedPassword)
{
byte[] saltedHash = Convert.FromBase64String(hashedPassword);
byte[] salt = new byte[SaltSize];
byte[] hash = new byte[HashSize];
// Extract the salt and hash from the combined bytes
Buffer.BlockCopy(saltedHash, 0, salt, 0, SaltSize);
Buffer.BlockCopy(saltedHash, SaltSize, hash, 0, HashSize);
byte[] computedHash = HashPasswordWithSalt(password, salt);
// Compare the computed hash with the stored hash
return SlowEquals(hash, computedHash);
}
private static byte[] HashPasswordWithSalt(string password, byte[] salt)
{
using (var deriveBytes = new Rfc2898DeriveBytes(password, salt, Iterations))
{
return deriveBytes.GetBytes(HashSize);
}
}
// Compares two byte arrays in a way that is resistant to timing attacks
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;
}
}
You can use the `HashPassword` method to hash a password and store it securely in your application's database. The `VerifyPassword` method can be used to compare a user-provided password with the stored hashed password to verify if they match.
