C# 对称加密解密算法子转换成T-sql代碼
可用于文件，和数据库字段的加解密。

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

namespace Comon
{
 /// <summary>
 /// KeyCryp 的摘要说明。
 /// </summary>
 public class KeyCryp
 {
  private SymmetricAlgorithm mobjCryptoService;
  private string Key;

  /// <summary>
  /// 对称加密类的构造函数
  /// </summary>
  public KeyCryp()
  {
  mobjCryptoService = new RijndaelManaged();
  Key = "Guz(%&hj7x89H$yuBI0456FtmaT5&fvHUFCy76*h%(HilJ$lhj!y6&(*jkP87jH7";
  }
  /// <summary>
  /// 获得密钥
  /// </summary>
  /// <returns>密钥</returns>
  private byte[] GetLegalKey()
  {
  string sTemp = Key;
  mobjCryptoService.GenerateKey();
  byte[] bytTemp = mobjCryptoService.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>
  /// 获得初始向量IV
  /// </summary>
  /// <returns>初试向量IV</returns>
  private byte[] GetLegalIV()
  {
  string sTemp = "E4ghj*Ghg7!rNIfb&95GUY86GfghUb#er57HBh(u%g6HJ($jhWk7&!hg4ui%$hjk";
  mobjCryptoService.GenerateIV();
  byte[] bytTemp = mobjCryptoService.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>经过加密的串</returns>
  public string Encrypto(string Source)
  {
  byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);
  MemoryStream ms = new MemoryStream();
  mobjCryptoService.Key = GetLegalKey();
  mobjCryptoService.IV = GetLegalIV();
  ICryptoTransform encrypto = mobjCryptoService.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);
  }
  /// <summary>
  /// 解密方法
  /// </summary>
  /// <param name="Source">待解密的串</param>
  /// <returns>经过解密的串</returns>
  public string Decrypto(string Source)
  {
  byte[] bytIn = Convert.FromBase64String(Source);
  MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
  mobjCryptoService.Key = GetLegalKey();
  mobjCryptoService.IV = GetLegalIV();
  ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();
  CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
  StreamReader sr = new StreamReader(cs);
  return sr.ReadToEnd();
  }
 
 }
}


------解决方案--------------------
SQL SERVER 2005 对称加密 
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