PBKDF2 functions for secure password storage, and supports custom iterations (defaults to a OWASP 2013 recommendation of 100,000). Created from decompiling the System.Web.Helpers.Crypto class.

gistfile1.cs

using System;
using System.Security.Cryptography;

namespace Nbevans.Cryptography {
    public static class Pbkdf2 {
        private const int Pbkdf2SubkeyLength = 32;
        private const int SaltSize = 16;

        private static bool ByteArraysEqual(byte[] a, byte[] b) {
            if (ReferenceEquals(a, b)) return true;
            if (a == null || b == null || a.Length != b.Length) return false;

            var flag = true;
            for (var i = 0; i < a.Length; i++)
                flag = flag & a[i] == b[i];

            return flag;
        }

        public static string Hash(string password, int iterations = 100000) {
            if (password == null) throw new ArgumentNullException("password");
            
            byte[] salt;
            byte[] bytes;
            using (var algo = new Rfc2898DeriveBytes(password, SaltSize, iterations)) {
                salt = algo.Salt;
                bytes = algo.GetBytes(Pbkdf2SubkeyLength);
            }

            var iters = BitConverter.GetBytes(iterations);
            if (!BitConverter.IsLittleEndian)
                Array.Reverse(iters);

            var parts = new byte[54];
            Buffer.BlockCopy(salt, 0, parts, 1, SaltSize);
            Buffer.BlockCopy(bytes, 0, parts, 17, Pbkdf2SubkeyLength);
            Buffer.BlockCopy(iters, 0, parts, 50, sizeof(int));
            return Convert.ToBase64String(parts);
        }

        public static bool Verify(string hashedPassword, string password) {
            if (hashedPassword == null) throw new ArgumentNullException("hashedPassword");
            if (password == null) throw new ArgumentNullException("password");
            
            var parts = Convert.FromBase64String(hashedPassword);
            if (parts.Length != 54 || parts[0] != 0)
                return false;

            var salt = new byte[SaltSize];
            Buffer.BlockCopy(parts, 1, salt, 0, SaltSize);

            var bytes = new byte[Pbkdf2SubkeyLength];
            Buffer.BlockCopy(parts, 17, bytes, 0, Pbkdf2SubkeyLength);

            var iters = new byte[sizeof(int)];
            Buffer.BlockCopy(parts, 50, iters, 0, sizeof(int));

            if (!BitConverter.IsLittleEndian)
                Array.Reverse(iters);

            var iterations = BitConverter.ToInt32(iters, 0);

            byte[] challengeBytes;
            using (var algo = new Rfc2898DeriveBytes(password, salt, iterations))
                challengeBytes = algo.GetBytes(32);

            return ByteArraysEqual(bytes, challengeBytes);
        }
    }
}