PasswordHash.cs

public class PasswordHash
{
    private const int SaltSize = 10;

    private const int HashSize = 40;

    private const int Iterations = 10000;

    private PasswordHash(byte[] hashBytes, byte[] saltBytes)
    {
        HashBytes = hashBytes;
        SaltBytes = saltBytes;
    }

    public byte[] HashBytes { get; private set; }
    
    public byte[] SaltBytes { get; private set; }

    public string HashBase64
    {
        get { return Convert.ToBase64String(HashBytes); }
    }

    public string SaltBase64
    {
        get { return Convert.ToBase64String(SaltBytes); }
    }

    public static PasswordHash Generate(string password, int hashSize = HashSize, int saltSize = SaltSize)
    {
        using (var hasher = new Rfc2898DeriveBytes(password, saltSize, Iterations))
        {
            return new PasswordHash(hasher.GetBytes(hashSize), hasher.Salt);
        }
    }

    public static PasswordHash From(string hashBase64, string saltBase64)
    {
        var hashBytes = Convert.FromBase64String(hashBase64);
        var saltBytes = Convert.FromBase64String(saltBase64);

        return From(hashBytes, saltBytes);
    }

    public static PasswordHash From(byte[] hashBytes, byte[] saltBytes)
    {
        return new PasswordHash(hashBytes, saltBytes);
    }
    
    public bool Verify(string password)
    {
        using (var hasher = new Rfc2898DeriveBytes(password, SaltBytes, Iterations))
        {
            return SlowEquals(hasher.GetBytes(HashBytes.Length), HashBytes);
        }
    }

    [MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.NoOptimization)]
    private static bool SlowEquals(IList<byte> a, IList<byte> b)
    {
        var diff = a.Count ^ b.Count;

        for (var i = 0; i < a.Count && i < b.Count; i++)
        {
            diff |= a[i] ^ b[i];
        }

        return diff == 0;
    }
}

Usage.cs

public class Usage
{
    private void Register(string username, string password)
    {
        var hash = PasswordHash.Generate(password);

        Database.Save(new User
        {
            Username = username,
            PasswordHash = hash.HashBase64,
            Salt = hash.SaltBase64
        });
    }  
    
    private bool Login(string username, string password)
    {
        var user = Database.Get(username);
        if (user == null) 
        {
            return false;
        }
        
        return PasswordHash.From(user.PasswordHash, user.Salt).Verify(password);
    } 
}