.Net中的加密與解密，.Net加密與解密
加密與解密概述
加密與解密屬於數據安全的范疇。在消息傳輸時，通過對消息進行特殊編碼（加密），建立一種安全的交流方式，使得只有發送者所期望的接收者能夠理解（解密）。這裡我們定義一個場景：發送方，接收方，第三方，發送方要將信息發送給接收方，二第三方想要截取並篡改消息，然後在轉發給接收方。要稱得上是安全的交流方式，需要滿足下面的3個條件：
下面將列出幾種常用的技術，看看是否符合上面的3個條件。
散列運算
散列（英語：Hashing）是電腦科學中一種對資料的處理方法，通過某種特定的函數/算法（稱為散列函數/算法）將要檢索的項與用來檢索的索引（稱為散列，或者散列值）關聯起來，生成一種便於搜索的數據結構（稱為散列表）。也譯為散列。舊譯哈希（誤以為是人名而采用了音譯）。它也常用作一種資訊安全的實作方法，由一串資料中經過散列算法（Hashing algorithms）計算出來的資料指紋（data fingerprint），經常用來識別檔案與資料是否有被竄改，以保證檔案與資料確實是由原創者所提供。
如今，散列算法也被用來加密存在數據庫中的密碼（password）字串，由於散列算法所計算出來的散列值（Hash Value）具有不可逆（無法逆向演算回原本的數值）的性質，因此可有效的保護密碼，我公司內的Web管理系統存儲的密碼字符串就是散列運算的摘要，確實很實用。
散列運算具有以下3個特點：
常見的散列運算如下圖所示：
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/// <summary>
/// 類說明：Assistant
/// 編 碼 人：蘇飛
/// 聯系方式：361983679
/// 更新網站：http://www.sufeinet.com/thread-655-1-1.html
/// </summary>
using System;
using System.Text;
using System.Security.Cryptography;
using System.IO;
using System.Text.RegularExpressions;
using System.Collections;
namespace DotNet.Utilities
{
/// <summary>
/// MySecurity(安全類) 的摘要說明。
/// </summary>
public class MySecurity
{
/// <summary>
/// 初始化安全類
/// </summary>
public MySecurity()
{
///默認密碼
key = "0123456789";
}
private string key; //默認密鑰
private byte[] sKey;
private byte[] sIV;
#region 加密字符串
/// <summary>
/// 加密字符串
/// </summary>
/// <param name="inputStr">輸入字符串</param>
/// <param name="keyStr">密碼，可以為“”</param>
/// <returns>輸出加密後字符串</returns>
static public string SEncryptString(string inputStr, string keyStr)
{
MySecurity ws = new MySecurity();
return ws.EncryptString(inputStr, keyStr);
}
/// <summary>
/// 加密字符串
/// </summary>
/// <param name="inputStr">輸入字符串</param>
/// <param name="keyStr">密碼，可以為“”</param>
/// <returns>輸出加密後字符串</returns>
public string EncryptString(string inputStr, string keyStr)
{
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
if (keyStr == "")
keyStr = key;
byte[] inputByteArray = Encoding.Default.GetBytes(inputStr);
byte[] keyByteArray = Encoding.Default.GetBytes(keyStr);
SHA1 ha = new SHA1Managed();
byte[] hb = ha.ComputeHash(keyByteArray);
sKey = new byte[8];
sIV = new byte[8];
for (int i = 0; i < 8; i++)
sKey[i] = hb[i];
for (int i = 8; i < 16; i++)
sIV[i - 8] = hb[i];
des.Key = sKey;
des.IV = sIV;
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
StringBuilder ret = new StringBuilder();
foreach (byte b in ms.ToArray())
{
ret.AppendFormat("{0:X2}", b);
}
cs.Close();
ms.Close();
return ret.ToString();
}
#endregion
#region 加密字符串 密鑰為系統默認 0123456789
/// <summary>
/// 加密字符串 密鑰為系統默認
/// </summary>
/// <param name="inputStr">輸入字符串</param>
/// <returns>輸出加密後字符串</returns>
static public string SEncryptString(string inputStr)
{
MySecurity ws = new MySecurity();
return ws.EncryptString(inputStr, "");
}
#endregion
#region 加密文件
/// <summary>
/// 加密文件
/// </summary>
/// <param name="filePath">輸入文件路徑</param>
/// <param name="savePath">加密後輸出文件路徑</param>
/// <param name="keyStr">密碼，可以為“”</param>
/// <returns></returns>
public bool EncryptFile(string filePath, string savePath, string keyStr)
{
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
if (keyStr == "")
keyStr = key;
FileStream fs = File.OpenRead(filePath);
byte[] inputByteArray = new byte[fs.Length];
fs.Read(inputByteArray, 0, (int)fs.Length);
fs.Close();
byte[] keyByteArray = Encoding.Default.GetBytes(keyStr);
SHA1 ha = new SHA1Managed();
byte[] hb = ha.ComputeHash(keyByteArray);
sKey = new byte[8];
sIV = new byte[8];
for (int i = 0; i < 8; i++)
sKey[i] = hb[i];
for (int i = 8; i < 16; i++)
sIV[i - 8] = hb[i];
des.Key = sKey;
des.IV = sIV;
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
fs = File.OpenWrite(savePath);
foreach (byte b in ms.ToArray())
{
fs.WriteByte(b);
}
fs.Close();
cs.Close();
ms.Close();
return true;
}
#endregion
#region 解密字符串
/// <summary>
/// 解密字符串
/// </summary>
/// <param name="inputStr">要解密的字符串</param>
/// <param name="keyStr">密鑰</param>
/// <returns>解密後的結果</returns>
static public string SDecryptString(string inputStr, string keyStr)
{
MySecurity ws = new MySecurity();
return ws.DecryptString(inputStr, keyStr);
}
/// <summary>
/// 解密字符串 密鑰為系統默認
/// </summary>
/// <param name="inputStr">要解密的字符串</param>
/// <returns>解密後的結果</returns>
static public string SDecryptString(string inputStr)
{
MySecurity ws = new MySecurity();
return ws.DecryptString(inputStr, "");
}
/// <summary>
/// 解密字符串
/// </summary>
/// <param name="inputStr">要解密的字符串</param>
/// <param name="keyStr">密鑰</param>
/// <returns>解密後的結果</returns>
public string DecryptString(string inputStr, string keyStr)
{
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
if (keyStr == "")
keyStr = key;
byte[] inputByteArray = new byte[inputStr.Length / 2];
for (int x = 0; x < inputStr.Length / 2; x++)
{
int i = (Convert.ToInt32(inputStr.Substring(x * 2, 2), 16));
inputByteArray[x] = (byte)i;
}
byte[] keyByteArray = Encoding.Default.GetBytes(keyStr);
SHA1 ha = new SHA1Managed();
byte[] hb = ha.ComputeHash(keyByteArray);
sKey = new byte[8];
sIV = new byte[8];
for (int i = 0; i < 8; i++)
sKey[i] = hb[i];
for (int i = 8; i < 16; i++)
sIV[i - 8] = hb[i];
des.Key = sKey;
des.IV = sIV;
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
StringBuilder ret = new StringBuilder();
return System.Text.Encoding.Default.GetString(ms.ToArray());
}
#endregion
#region 解密文件
/// <summary>
/// 解密文件
/// </summary>
/// <param name="filePath">輸入文件路徑</param>
/// <param name="savePath">解密後輸出文件路徑</param>
/// <param name="keyStr">密碼，可以為“”</param>
/// <returns></returns>
public bool DecryptFile(string filePath, string savePath, string keyStr)
{
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
if (keyStr == "")
keyStr = key;
FileStream fs = File.OpenRead(filePath);
byte[] inputByteArray = new byte[fs.Length];
fs.Read(inputByteArray, 0, (int)fs.Length);
fs.Close();
byte[] keyByteArray = Encoding.Default.GetBytes(keyStr);
SHA1 ha = new SHA1Managed();
byte[] hb = ha.ComputeHash(keyByteArray);
sKey = new byte[8];
sIV = new byte[8];
for (int i = 0; i < 8; i++)
sKey[i] = hb[i];
for (int i = 8; i < 16; i++)
sIV[i - 8] = hb[i];
des.Key = sKey;
des.IV = sIV;
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
fs = File.OpenWrite(savePath);
foreach (byte b in ms.ToArray())
{
fs.WriteByte(b);
}
fs.Close();
cs.Close();
ms.Close();
return true;
}
#endregion
#region MD5加密
/// <summary>
/// 128位MD5算法加密字符串
/// </summary>
/// <param name="text">要加密的字符串</param>
public static string MD5(string text)
{
//如果字符串為空，則返回
if (Tools.IsNullOrEmpty<string>(text))
{
return "";
}
//返回MD5值的字符串表示
return MD5(text);
}
/// <summary>
/// 128位MD5算法加密Byte數組
/// </summary>
/// <param name="data">要加密的Byte數組</param>
public static string MD5(byte[] data)
{
//如果Byte數組為空，則返回
if (Tools.IsNullOrEmpty<byte[]>(data))
{
return "";
}
try
{
//創建MD5密碼服務提供程序
MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
//計算傳入的字節數組的哈希值
byte[] result = md5.ComputeHash(data);
//釋放資源
md5.Clear();
//返回MD5值的字符串表示
return Convert.ToBase64String(result);
}
catch
{
//LogHelper.WriteTraceLog(TraceLogLevel.Error, ex.Message);
return "";
}
}
#endregion
#region Base64加密
/// <summary>
/// Base64加密
/// </summary>
/// <param name="text">要加密的字符串</param>
/// <returns></returns>
public static string EncodeBase64(string text)
{
//如果字符串為空，則返回
if (Tools.IsNullOrEmpty<string>(text))
{
return "";
}
try
{
char[] Base64Code = new char[]{'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T',
'U','V','W','X','Y','Z','a','b','c','d','e','f','g','h','i','j','k','l','m','n',
'o','p','q','r','s','t','u','v','w','x','y','z','0','1','2','3','4','5','6','7',
'8','9','+','/','='};
byte empty = (byte)0;
ArrayList byteMessage = new ArrayList(Encoding.Default.GetBytes(text));
StringBuilder outmessage;
int messageLen = byteMessage.Count;
int page = messageLen / 3;
int use = 0;
if ((use = messageLen % 3) > 0)
{
for (int i = 0; i < 3 - use; i++)
byteMessage.Add(empty);
page++;
}
outmessage = new System.Text.StringBuilder(page * 4);
for (int i = 0; i < page; i++)
{
byte[] instr = new byte[3];
instr[0] = (byte)byteMessage[i * 3];
instr[1] = (byte)byteMessage[i * 3 + 1];
instr[2] = (byte)byteMessage[i * 3 + 2];
int[] outstr = new int[4];
outstr[0] = instr[0] >> 2;
outstr[1] = ((instr[0] & 0x03) << 4) ^ (instr[1] >> 4);
if (!instr[1].Equals(empty))
outstr[2] = ((instr[1] & 0x0f) << 2) ^ (instr[2] >> 6);
else
outstr[2] = 64;
if (!instr[2].Equals(empty))
outstr[3] = (instr[2] & 0x3f);
else
outstr[3] = 64;
outmessage.Append(Base64Code[outstr[0]]);
outmessage.Append(Base64Code[outstr[1]]);
outmessage.Append(Base64Code[outstr[2]]);
outmessage.Append(Base64Code[outstr[3]]);
}
return outmessage.ToString();
}
catch (Exception ex)
{
throw ex;
}
}
#endregion
#region Base64解密
/// <summary>
/// Base64解密
/// </summary>
/// <param name="text">要解密的字符串</param>
public static string DecodeBase64(string text)
{
//如果字符串為空，則返回
if (Tools.IsNullOrEmpty<string>(text))
{
return "";
}
//將空格替換為加號
text = text.Replace(" ", "+");
try
{
if ((text.Length % 4) != 0)
{
return "包含不正確的BASE64編碼";
}
if (!Regex.IsMatch(text, "^[A-Z0-9/+=]*$", RegexOptions.IgnoreCase))
{
return "包含不正確的BASE64編碼";
}
string Base64Code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
int page = text.Length / 4;
ArrayList outMessage = new ArrayList(page * 3);
char[] message = text.ToCharArray();
for (int i = 0; i < page; i++)
{
byte[] instr = new byte[4];
instr[0] = (byte)Base64Code.IndexOf(message[i * 4]);
instr[1] = (byte)Base64Code.IndexOf(message[i * 4 + 1]);
instr[2] = (byte)Base64Code.IndexOf(message[i * 4 + 2]);
instr[3] = (byte)Base64Code.IndexOf(message[i * 4 + 3]);
byte[] outstr = new byte[3];
outstr[0] = (byte)((instr[0] << 2) ^ ((instr[1] & 0x30) >> 4));
if (instr[2] != 64)
{
outstr[1] = (byte)((instr[1] << 4) ^ ((instr[2] & 0x3c) >> 2));
}
else
{
outstr[2] = 0;
}
if (instr[3] != 64)
{
outstr[2] = (byte)((instr[2] << 6) ^ instr[3]);
}
else
{
outstr[2] = 0;
}
outMessage.Add(outstr[0]);
if (outstr[1] != 0)
outMessage.Add(outstr[1]);
if (outstr[2] != 0)
outMessage.Add(outstr[2]);
}
byte[] outbyte = (byte[])outMessage.ToArray(Type.GetType("System.Byte"));
return Encoding.Default.GetString(outbyte);
}
catch (Exception ex)
{
throw ex;
}
}
#endregion
}
}
怎在net中使用MD5加密與解密
1、.NET中采用MD5加密直接采用MD5CryptoServiceProvider類即可完成
2、MD5與SHA1都是單向的散列加密，即使單向的不可逆加密方式，主要用於賬號密碼等的驗證或數字簽名等，無法根據其散列數值，解密出其原來數值。
3、更多交流，參考我空間有關文章。
net中，md5具體怎使用加密與解密
using System;
using System.Text;
using System.Security.Cryptography;
namespace MD5
{
public class MD5
{
// 32 位
public static String Encrypt(String s)
{
MD5 md5 = new MD5CryptoServiceProvider();
byte[] bytes = System.Text.Encoding.UTF8.GetBytes(s);
bytes = md5.ComputeHash(bytes);
md5.Clear();
string ret = "";
for (int i = 0; i < bytes.Length; i++)
{
ret += Convert.ToString(bytes[i], 16).PadLeft(2, '0');
}
return ret.PadLeft(32, '0');
}
// 16 位
public static string Encrypt16(string ConvertString)
{
MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
string t2 = BitConverter.ToString(md5.ComputeHash(UTF8Encoding.Default.GetBytes(ConvertString)), 4, 8);
t2 = t2.Replace("-", "");
return t2;
}
}
}
-------------------------------------
引用MD5命名空間
using MD5;
直接用MD5.Encrypt(textbox1.Text);即可加密；
MD5沒有解密的算法，要不然就不用加密了，網上有一些解密的網站，有些能解密，有些解密不了，有些還需要收費才能解密。
