namespace com.hitrust.util.Encryption
{
    using com.hitrust.util.Checksums;
    using System;
    using System.Security.Cryptography;

    public abstract class PkzipClassic : SymmetricAlgorithm
    {
        protected PkzipClassic()
        {
        }

        public static byte[] GenerateKeys(byte[] seed)
        {
            if (seed == null)
            {
                throw new ArgumentNullException("seed");
            }
            if (seed.Length == 0)
            {
                throw new ArgumentException("Length is zero", "seed");
            }
            uint[] newKeys = new uint[] { 0x12345678, 0x23456789, 0x34567890 };
            for (int i = 0; i < seed.Length; i++)
            {
                newKeys[0] = Crc32.ComputeCrc32(newKeys[0], seed[i]);
                newKeys[1] += (byte) newKeys[0];
                newKeys[1] = (newKeys[1] * 0x8088405) + 1;
                newKeys[2] = Crc32.ComputeCrc32(newKeys[2], (byte) (newKeys[1] >> 0x18));
            }
            return new byte[] { ((byte) (newKeys[0] & 0xff)), ((byte) ((newKeys[0] >> 8) & 0xff)), ((byte) ((newKeys[0] >> 0x10) & 0xff)), ((byte) ((newKeys[0] >> 0x18) & 0xff)), ((byte) (newKeys[1] & 0xff)), ((byte) ((newKeys[1] >> 8) & 0xff)), ((byte) ((newKeys[1] >> 0x10) & 0xff)), ((byte) ((newKeys[1] >> 0x18) & 0xff)), ((byte) (newKeys[2] & 0xff)), ((byte) ((newKeys[2] >> 8) & 0xff)), ((byte) ((newKeys[2] >> 0x10) & 0xff)), ((byte) ((newKeys[2] >> 0x18) & 0xff)) };
        }
    }
}