软件注册码（算法一DES）

DES，Rijndael，BouncyCastle

/// <summary>
    /// 加密，解密 接口
    /// </summary>
    public interface ICrypto
    {
        /// <summary>
        /// 加密
        /// </summary>
        /// <param name="bytes"></param>
        /// <returns></returns>
        byte[] Encrypt(byte[] bytes);
        /// <summary>
        /// 解密
        /// </summary>
        /// <param name="bytes"></param>
        /// <returns></returns>
        byte[] Decrypt(byte[] bytes);
    }

 /// <summary>
    /// DES算法
    /// </summary>
    public class DESCrypto : ICrypto
    {
        private byte[] _key;
        private byte[] _iv = new byte[] { 107, 22, 226, 145, 208, 243, 46, 41 };
        private DESCryptoServiceProvider GetProvider()
        {
            DESCryptoServiceProvider descsp = new DESCryptoServiceProvider();
            descsp.IV = this._iv;
            descsp.Key = this._key;
            return descsp;
        }
        public DESCrypto(byte[] key)
        {
            this._key = key;
        }
        /// <summary>
        /// 加密
        /// </summary>
        /// <param name="bytes"></param>
        /// <returns></returns>
        public byte[] Encrypt(byte[] bytes)
        {
            DESCryptoServiceProvider descsp = this.GetProvider();
            ICryptoTransform it = descsp.CreateEncryptor(descsp.Key, descsp.IV);
            return it.TransformFinalBlock(bytes, 0, bytes.Length);
        }
        /// <summary>
        /// 解密
        /// </summary>
        /// <param name="bytes"></param>
        /// <returns></returns>
        public byte[] Decrypt(byte[] bytes)
        {
            DESCryptoServiceProvider descsp = this.GetProvider();
            ICryptoTransform it = descsp.CreateDecryptor(descsp.Key, descsp.IV);
            return it.TransformFinalBlock(bytes, 0, bytes.Length);
        }
    }

1：建立LicenseInfo类，来完成软件的版本或者过期时间信息

 public class LicenseInfo
    {
        public byte LicenseType { get; set; }
        public int ExhaustionDayTicks { get; set; }
        public LicenseInfo()
        {
        }
        public LicenseInfo(byte licenseType, int exhaustionDayTicks)
        {
            this.LicenseType = licenseType;
            this.ExhaustionDayTicks = exhaustionDayTicks;
        }
        public byte[] ToByteArray()
        {
            byte[] bytes = new byte[5];
            bytes[0] = LicenseType;
            byte[] exhaustBytes = BitConverter.GetBytes(ExhaustionDayTicks);
            for (int i = 0; i < 4; i++)
            {
                bytes[i + 1] = exhaustBytes[i];
            }
            return bytes;
        }
        public static LicenseInfo FromByteArray(byte[] bytes)
        {
            LicenseInfo licenseInfo = new LicenseInfo();
            licenseInfo.LicenseType = bytes[0];
            licenseInfo.ExhaustionDayTicks = BitConverter.ToInt32(bytes, 1);
            return licenseInfo;
        }
    }

2：建立Client客户端类，生成客户端序列号

public byte[] GetProductKeyBytes(string pid)
        {
            string productKey = pid;
            byte[] bytes = Utils.GetBytes(productKey);
            byte[] hashBytes = Utils.ComputeHash(bytes);
            byte[] initHash = new byte[8] { 139, 59, 237, 93, 177, 134, 88, 69 };
            byte[] mergedHash = new byte[8];
            for (int i = 0; i < 8; i++)
            {
                mergedHash[i] = (byte)(initHash[i] ^ hashBytes[i] ^ hashBytes[i + 8]);
            }
            return mergedHash;
        }
        /// <summary>
        /// 序列号
        /// </summary>
        /// <param name="pid"></param>
        /// <returns></returns>
        public string GetProductKey(string pid)
        {
            byte[] productKeyBytes = GetProductKeyBytes(pid);
            return Utils.ConvertBytesToHexString(productKeyBytes);
        }

3：软件制作者用客户端的序列号加密成注册码，发送给客户

4：客户验证注册码，进入软件

 /// <summary>
        /// 验证注册码
        /// </summary>
        /// <param name="productKey"></param>
        /// <param name="activationCode"></param>
        /// <param name="systemDate"></param>
        /// <param name="licenseInfo"></param>
        /// <returns></returns>
        public bool ValidateLicense(string productKey, string activationCode, DateTime systemDate, out LicenseInfo licenseInfo)
        {
            licenseInfo = null;
            if (string.IsNullOrEmpty(productKey) || string.IsNullOrEmpty(activationCode)) return false;
            byte[] productKeyBytes = Utils.ConvertHexStringToBytes(productKey);
            byte[] activationCodeBytes = Utils.ConvertHexStringToBytes(activationCode);
            licenseInfo = null;
            try
            {
                byte[] licenseInfoBytes = CryptoFactory.GetCrypto(productKeyBytes).Decrypt(activationCodeBytes);
                licenseInfo = LicenseInfo.FromByteArray(licenseInfoBytes);
                DateTime exhaustionDate = new DateTime(1900, 1, 1).AddDays(licenseInfo.ExhaustionDayTicks);
                return exhaustionDate > systemDate;
            }
            catch (Exception)
            {
                return false;
            }
        }