?using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace ZYBEncrypt
{
    /// <summary>
    /// RC2
    /// </summary>
    public class RC2_
    {
        private RC2 rc;
        public string Key;
        public string IV;
        /// <summary>
        /// 對稱加密類的構造函數
        /// </summary>
        public RC2_(string key)
        {
            rc = new RC2CryptoServiceProvider();
            Key = key;
            IV = "#$^%&&*Yisifhsfjsljfslhgosdshf26382837sdfjskhf97(*&(*";
        }
        /// <summary>
        /// 對稱加密類的構造函數
        /// </summary>
        public RC2_(string key, string iv)
        {
            rc = new RC2CryptoServiceProvider();
            Key = key;
            IV = iv;
        }
        /// <summary>
        /// 獲得密鑰
        /// </summary>
        /// <returns>密鑰</returns>
        private byte[] GetLegalKey()
        {
            string sTemp = Key;
            rc.GenerateKey();
            byte[] bytTemp = rc.Key;
            int KeyLength = bytTemp.Length;
            if (sTemp.Length > KeyLength)
                sTemp = sTemp.Substring(0, KeyLength);
            else if (sTemp.Length < KeyLength)
                sTemp = sTemp.PadRight(KeyLength, ' ');
            return ASCIIEncoding.ASCII.GetBytes(sTemp);
        }
        /// <summary>
        /// 獲得初始向量IV
        /// </summary>
        /// <returns>初試向量IV</returns>
        private byte[] GetLegalIV()
        {
            string sTemp = IV;
            rc.GenerateIV();
            byte[] bytTemp = rc.IV;
            int IVLength = bytTemp.Length;
            if (sTemp.Length > IVLength)
                sTemp = sTemp.Substring(0, IVLength);
            else if (sTemp.Length < IVLength)
                sTemp = sTemp.PadRight(IVLength, ' ');
            return ASCIIEncoding.ASCII.GetBytes(sTemp);
        }
        /// <summary>
        /// 加密方法
        /// </summary>
        /// <param name="Source">待加密的串</param>
        /// <returns>經過加密的串</returns>
        public string Encrypt(string Source)
        {
            try
            {
                byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);
                MemoryStream ms = new MemoryStream();
                rc.Key = GetLegalKey();
                rc.IV = GetLegalIV();
                ICryptoTransform encrypto = rc.CreateEncryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
                cs.Write(bytIn, 0, bytIn.Length);
                cs.FlushFinalBlock();
                ms.Close();
                byte[] bytOut = ms.ToArray();
                return Convert.ToBase64String(bytOut);
            }
            catch (Exception ex)
            {
                throw new Exception("在文件加密的時候出現錯誤！錯誤提示： \n" + ex.Message);
            }
        }
        /// <summary>
        /// 解密方法
        /// </summary>
        /// <param name="Source">待解密的串</param>
        /// <returns>經過解密的串</returns>
        public string Decrypt(string Source)
        {
            try
            {
                byte[] bytIn = Convert.FromBase64String(Source);
                MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
                rc.Key = GetLegalKey();
                rc.IV = GetLegalIV();
                ICryptoTransform encrypto = rc.CreateDecryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
                StreamReader sr = new StreamReader(cs);
                return sr.ReadToEnd();
            }
            catch (Exception ex)
            {
                throw new Exception("在文件解密的時候出現錯誤！錯誤提示： \n" + ex.Message);
            }
        }
        /// <summary>
        /// 加密方法byte[] to byte[]
        /// </summary>
        /// <param name="Source">待加密的byte數組</param>
        /// <returns>經過加密的byte數組</returns>
        public byte[] Encrypt(byte[] Source)
        {
            try
            {
                byte[] bytIn = Source;
                MemoryStream ms = new MemoryStream();
                rc.Key = GetLegalKey();
                rc.IV = GetLegalIV();
                ICryptoTransform encrypto = rc.CreateEncryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
                cs.Write(bytIn, 0, bytIn.Length);
                cs.FlushFinalBlock();
                ms.Close();
                byte[] bytOut = ms.ToArray();
                return bytOut;
            }
            catch (Exception ex)
            {
                throw new Exception("在文件加密的時候出現錯誤！錯誤提示： \n" + ex.Message);
            }
        }
        /// <summary>
        /// 解密方法byte[] to byte[]
        /// </summary>
        /// <param name="Source">待解密的byte數組</param>
        /// <returns>經過解密的byte數組</returns>
        public byte[] Decrypt(byte[] Source)
        {
            try
            {
                byte[] bytIn = Source;
                MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
                rc.Key = GetLegalKey();
                rc.IV = GetLegalIV();
                ICryptoTransform encrypto = rc.CreateDecryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
                StreamReader sr = new StreamReader(cs);
                return UTF8Encoding.UTF8.GetBytes(sr.ReadToEnd());
            }
            catch (Exception ex)
            {
                throw new Exception("在文件解密的時候出現錯誤！錯誤提示： \n" + ex.Message);
            }
        }


        /// <summary>
        /// 加密方法File to File
        /// </summary>
        /// <param name="inFileName">待加密文件的路徑</param>
        /// <param name="outFileName">待加密后文件的輸出路徑</param>

        public void Encrypt(string inFileName, string outFileName)
        {
            try
            {

                FileStream fin = new FileStream(inFileName, FileMode.Open, FileAccess.Read);
                FileStream fout = new FileStream(outFileName, FileMode.OpenOrCreate, FileAccess.Write);
                fout.SetLength(0);

                rc.Key = GetLegalKey();
                rc.IV = GetLegalIV();

                byte[] bin = new byte[100];
                long rdlen = 0;
                long totlen = fin.Length;
                int len;

                ICryptoTransform encrypto = rc.CreateEncryptor();
                CryptoStream cs = new CryptoStream(fout, encrypto, CryptoStreamMode.Write);
                while (rdlen < totlen)
                {
                    len = fin.Read(bin, 0, 100);
                    cs.Write(bin, 0, len);
                    rdlen = rdlen + len;
                }
                cs.Close();
                fout.Close();
                fin.Close();

            }
            catch (Exception ex)
            {
                throw new Exception("在文件加密的時候出現錯誤！錯誤提示： \n" + ex.Message);
            }
        }
        /// <summary>
        /// 解密方法File to File
        /// </summary>
        /// <param name="inFileName">待解密文件的路徑</param>
        /// <param name="outFileName">待解密后文件的輸出路徑</param>
        public void Decrypt(string inFileName, string outFileName)
        {
            try
            {
                FileStream fin = new FileStream(inFileName, FileMode.Open, FileAccess.Read);
                FileStream fout = new FileStream(outFileName, FileMode.OpenOrCreate, FileAccess.Write);
                fout.SetLength(0);

                byte[] bin = new byte[100];
                long rdlen = 0;
                long totlen = fin.Length;
                int len;
                rc.Key = GetLegalKey();
                rc.IV = GetLegalIV();
                ICryptoTransform encrypto = rc.CreateDecryptor();
                CryptoStream cs = new CryptoStream(fout, encrypto, CryptoStreamMode.Write);
                while (rdlen < totlen)
                {
                    len = fin.Read(bin, 0, 100);
                    cs.Write(bin, 0, len);
                    rdlen = rdlen + len;
                }
                cs.Close();
                fout.Close();
                fin.Close();

            }
            catch (Exception ex)
            {
                throw new Exception("在文件解密的時候出現錯誤！錯誤提示： \n" + ex.Message);
            }
        }

    }
}