数据的加密重要性大家皆知，很多情况下需要对数据进行加密处理，但各种重要数据的加密要求不一样，有些需要时可逆的，有些是不要求可逆的，可逆的一般称之为对称加密算法，不可逆的一般可以成为非对称加密算法。如登录密码，一般较好的方式是采用不可逆的加密算法，如MD5、SHA256、哈希数值等，当然也有的采用可逆的强度好一些的加密方式，在选择加密键值的时候，变化一下也算是比较不错的选择。另外一些为了掩人耳目或者不让别人直接可以查看到，就采用其他的加密算法，如DES加密算法、AES的RijndaelManaged加密算法，或者也可以采用Base64加密，甚至我看到一个很变态的方式，就是用MD5加密的头，内容则采用Base64的方式加密，一般不知道内情的还真的不好处理。
在吉日《[走火入魔失眠夜]浅谈管理软件信息安全，用户名、密码的加密解密【附C#配套加密解密源码】》 的文章中也对加密做了一些介绍和分析，并贴出了MD5、DES的加密方式代码，吉日的文章图文并茂、哲理及诙谐例子并存，本文有感而发，做一些补充，希望园子同行共通过切磋，交流心得。
加密字符串的方式有很多，也都可以通过这样的加密文件内容，不过较好的方式可能是采用DES及AES两种方式来加密文件了，下面贴出的代码中包含了加解密文件的算法。下面具体贴出本人收藏的各种加密算法代码。
1、DES加密字符串及文件等
如果想可逆的算法，这种方式一般不错，只要结合动态密钥，就可以做出强度比较高的加密应用了。
#region DES对称加密解密
public const string DEFAULT_ENCRYPT_KEY = "12345678";
/// <summary>
/// 使用默认加密
/// </summary>
/// <param name="strText"></param>
/// <returns></returns>
public static string DesEncrypt(string strText)
{
try
{
return DesEncrypt(strText, DEFAULT_ENCRYPT_KEY);
}
catch
{
return "";
}
}
/// <summary>
/// 使用默认解密
/// </summary>
/// <param name="strText"></param>
/// <returns></returns>
public static string DesDecrypt(string strText)
{
try
{
return DesDecrypt(strText, DEFAULT_ENCRYPT_KEY);
}
catch
{
return "";
}
}
/// <summary>
/// Encrypt the string
/// Attention:key must be 8 bits
/// </summary>
/// <param name="strText">string</param>
/// <param name="strEncrKey">key</param>
/// <returns></returns>
public static string DesEncrypt(string strText, string strEncrKey)
{
byte[] byKey = null;
byte[] IV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
byKey = Encoding.UTF8.GetBytes(strEncrKey.Substring(0, 8));
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
byte[] inputByteArray = Encoding.UTF8.GetBytes(strText);
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(byKey, IV), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
return Convert.ToBase64String(ms.ToArray());
}
/// <summary>
/// Decrypt string
/// Attention:key must be 8 bits
/// </summary>
/// <param name="strText">Decrypt string</param>
/// <param name="sDecrKey">key</param>
/// <returns>output string</returns>
public static string DesDecrypt(string strText, string sDecrKey)
{
byte[] byKey = null;
byte[] IV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
byte[] inputByteArray = new Byte[strText.Length];
byKey = Encoding.UTF8.GetBytes(sDecrKey.Substring(0, 8));
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
inputByteArray = Convert.FromBase64String(strText);
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(byKey, IV), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
Encoding encoding = new UTF8Encoding();
return encoding.GetString(ms.ToArray());
}
/// <summary>
/// Encrypt files
/// Attention:key must be 8 bits
/// </summary>
/// <param name="m_InFilePath">Encrypt file path</param>
/// <param name="m_OutFilePath">output file</param>
/// <param name="strEncrKey">key</param>
public static void DesEncrypt(string m_InFilePath, string m_OutFilePath, string strEncrKey)
{
byte[] byKey = null;
byte[] IV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
byKey = Encoding.UTF8.GetBytes(strEncrKey.Substring(0, 8));
FileStream fin = new FileStream(m_InFilePath, FileMode.Open, FileAccess.Read);
FileStream fout = new FileStream(m_OutFilePath, FileMode.OpenOrCreate, FileAccess.Write);
fout.SetLength(0);
//Create variables to help with read and write.
byte[] bin = new byte[100]; //This is intermediate storage for the encryption.
long rdlen = 0; //This is the total number of bytes written.
long totlen = fin.Length; //This is the total length of the input file.
int len; //This is the number of bytes to be written at a time.
DES des = new DESCryptoServiceProvider();
CryptoStream encStream = new CryptoStream(fout, des.CreateEncryptor(byKey, IV), CryptoStreamMode.Write);
//Read from the input file, then encrypt and write to the output file.
while (rdlen < totlen)
{
len = fin.Read(bin, 0, 100);
encStream.Write(bin, 0, len);
rdlen = rdlen + len;
}
encStream.Close();
fout.Close();
fin.Close();
}
/// <summary>
/// Decrypt files
/// Attention:key must be 8 bits
/// </summary>
/// <param name="m_InFilePath">Decrypt filepath</param>
/// <param name="m_OutFilePath">output filepath</param>
/// <param name="sDecrKey">key</param>
public static void DesDecrypt(string m_InFilePath, string m_OutFilePath, string sDecrKey)
{
byte[] byKey = null;
byte[] IV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
byKey = Encoding.UTF8.GetBytes(sDecrKey.Substring(0, 8));
FileStream fin = new FileStream(m_InFilePath, FileMode.Open, FileAccess.Read);
FileStream fout = new FileStream(m_OutFilePath, FileMode.OpenOrCreate, FileAccess.Write);
fout.SetLength(0);
//Create variables to help with read and write.
byte[] bin = new byte[100]; //This is intermediate storage for the encryption.
long rdlen = 0; //This is the total number of bytes written.
long totlen = fin.Length; //This is the total length of the input file.
int len; //This is the number of bytes to be written at a time.
DES des = new DESCryptoServiceProvider();
CryptoStream encStream = new CryptoStream(fout, des.CreateDecryptor(byKey, IV), CryptoStreamMode.Write);
//Read from the input file, then encrypt and write to the output file.
while (rdlen < totlen)
{
len = fin.Read(bin, 0, 100);
encStream.Write(bin, 0, len);
rdlen = rdlen + len;
}
encStream.Close();
fout.Close();
fin.Close();
}
#endregion
2、 对称加密算法AES RijndaelManaged加密解密
#region 对称加密算法AES RijndaelManaged加密解密
private static readonly string Default_AES_Key = "@#kim123";
private static byte[] Keys = { 0x41, 0x72, 0x65, 0x79, 0x6F, 0x75, 0x6D, 0x79,
0x53,0x6E, 0x6F, 0x77, 0x6D, 0x61, 0x6E, 0x3F };
/// <summary>
/// 对称加密算法AES RijndaelManaged加密(RijndaelManaged（AES）算法是块式加密算法)
/// </summary>
/// <param name="encryptString">待加密字符串</param>
/// <returns>加密结果字符串</returns>
public static string AES_Encrypt(string encryptString)
{
return AES_Encrypt(encryptString, Default_AES_Key);
}
/// <summary>
/// 对称加密算法AES RijndaelManaged加密(RijndaelManaged（AES）算法是块式加密算法)
/// </summary>
/// <param name="encryptString">待加密字符串</param>
/// <param name="encryptKey">加密密钥，须半角字符</param>
/// <returns>加密结果字符串</returns>
public static string AES_Encrypt(string encryptString, string encryptKey)
{
encryptKey = GetSubString(encryptKey, 32, "");
encryptKey = encryptKey.PadRight(32, ' ');
RijndaelManaged rijndaelProvider = new RijndaelManaged();
rijndaelProvider.Key = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 32));
rijndaelProvider.IV = Keys;
ICryptoTransform rijndaelEncrypt = rijndaelProvider.CreateEncryptor();
byte[] inputData = Encoding.UTF8.GetBytes(encryptString);
byte[] encryptedData = rijndaelEncrypt.TransformFinalBlock(inputData, 0, inputData.Length);
return Convert.ToBase64String(encryptedData);
}
/// <summary>
/// 对称加密算法AES RijndaelManaged解密字符串
/// </summary>
/// <param name="decryptString">待解密的字符串</param>
/// <returns>解密成功返回解密后的字符串,失败返源串</returns>
public static string AES_Decrypt(string decryptString)
{
return AES_Decrypt(decryptString, Default_AES_Key);
}
/// <summary>
/// 对称加密算法AES RijndaelManaged解密字符串
/// </summary>
/// <param name="decryptString">待解密的字符串</param>
/// <param name="decryptKey">解密密钥,和加密密钥相同</param>
/// <returns>解密成功返回解密后的字符串,失败返回空</returns>
public static string AES_Decrypt(string decryptString, string decryptKey)
{
try
{
decryptKey = GetSubString(decryptKey, 32, "");
decryptKey = decryptKey.PadRight(32, ' ');
RijndaelManaged rijndaelProvider = new RijndaelManaged();
rijndaelProvider.Key = Encoding.UTF8.GetBytes(decryptKey);
rijndaelProvider.IV = Keys;
ICryptoTransform rijndaelDecrypt = rijndaelProvider.CreateDecryptor();
byte[] inputData = Convert.FromBase64String(decryptString);
byte[] decryptedData = rijndaelDecrypt.TransformFinalBlock(inputData, 0, inputData.Length);
return Encoding.UTF8.GetString(decryptedData);
}
catch
{
return string.Empty;
}
}
/// <summary>
/// 按字节长度(按字节,一个汉字为2个字节)取得某字符串的一部分
/// </summary>
/// <param name="sourceString">源字符串</param>
/// <param name="length">所取字符串字节长度</param>
/// <param name="tailString">附加字符串(当字符串不够长时，尾部所添加的字符串，一般为"...")</param>
/// <returns>某字符串的一部分</returns>
private static string GetSubString(string sourceString, int length, string tailString)
{
return GetSubString(sourceString, 0, length, tailString);
}
/// <summary>
/// 按字节长度(按字节,一个汉字为2个字节)取得某字符串的一部分
/// </summary>
/// <param name="sourceString">源字符串</param>
/// <param name="startIndex">索引位置，以0开始</param>
/// <param name="length">所取字符串字节长度</param>
/// <param name="tailString">附加字符串(当字符串不够长时，尾部所添加的字符串，一般为"...")</param>
/// <returns>某字符串的一部分</returns>
private static string GetSubString(string sourceString, int startIndex, int length, string tailString)
{
string myResult = sourceString;
//当是日文或韩文时(注:中文的范围:\u4e00 - \u9fa5, 日文在\u0800 - \u4e00, 韩文为\xAC00-\xD7A3)
if (System.Text.RegularExpressions.Regex.IsMatch(sourceString, "[\u0800-\u4e00]+") ||
System.Text.RegularExpressions.Regex.IsMatch(sourceString, "[\xAC00-\xD7A3]+"))
{
//当截取的起始位置超出字段串长度时
if (startIndex >= sourceString.Length)
{
return string.Empty;
}
else
{
return sourceString.Substring(startIndex,
((length + startIndex) > sourceString.Length) ? (sourceString.Length - startIndex) : length);
}
}
//中文字符，如"中国人民abcd123"
if (length <= 0)
{
return string.Empty;
}
byte[] bytesSource = Encoding.Default.GetBytes(sourceString);
//当字符串长度大于起始位置
if (bytesSource.Length > startIndex)
{
int endIndex = bytesSource.Length;
//当要截取的长度在字符串的有效长度范围内
if (bytesSource.Length > (startIndex + length))
{
endIndex = length + startIndex;
}
else
{ //当不在有效范围内时,只取到字符串的结尾
length = bytesSource.Length - startIndex;
tailString = "";
}
int[] anResultFlag = new int[length];
int nFlag = 0;
//字节大于127为双字节字符
for (int i = startIndex; i < endIndex; i++)
{
if (bytesSource[i] > 127)
{
nFlag++;
if (nFlag == 3)
{
nFlag = 1;
}
}
else
{
nFlag = 0;
}
anResultFlag[i] = nFlag;
}
//最后一个字节为双字节字符的一半
if ((bytesSource[endIndex - 1] > 127) && (anResultFlag[length - 1] == 1))
{
length = length + 1;
}
byte[] bsResult = new byte[length];
Array.Copy(bytesSource, startIndex, bsResult, 0, length);
myResult = Encoding.Default.GetString(bsResult);
myResult = myResult + tailString;
return myResult;
}
return string.Empty;
}
/// <summary>
/// 加密文件流
/// </summary>
/// <param name="fs"></param>
/// <returns></returns>
public static CryptoStream AES_EncryptStrream(FileStream fs, string decryptKey)
{
decryptKey = GetSubString(decryptKey, 32, "");
decryptKey = decryptKey.PadRight(32, ' ');
RijndaelManaged rijndaelProvider = new RijndaelManaged();
rijndaelProvider.Key = Encoding.UTF8.GetBytes(decryptKey);
rijndaelProvider.IV = Keys;
ICryptoTransform encrypto = rijndaelProvider.CreateEncryptor();
CryptoStream cytptostreamEncr = new CryptoStream(fs, encrypto, CryptoStreamMode.Write);
return cytptostreamEncr;
}
/// <summary>
/// 解密文件流
/// </summary>
/// <param name="fs"></param>
/// <returns></returns>
public static CryptoStream AES_DecryptStream(FileStream fs, string decryptKey)
{
decryptKey = GetSubString(decryptKey, 32, "");
decryptKey = decryptKey.PadRight(32, ' ');
RijndaelManaged rijndaelProvider = new RijndaelManaged();
rijndaelProvider.Key = Encoding.UTF8.GetBytes(decryptKey);
rijndaelProvider.IV = Keys;
ICryptoTransform Decrypto = rijndaelProvider.CreateDecryptor();
CryptoStream cytptostreamDecr = new CryptoStream(fs, Decrypto, CryptoStreamMode.Read);
return cytptostreamDecr;
}
/// <summary>
/// 对指定文件加密
/// </summary>
/// <param name="InputFile"></param>
/// <param name="OutputFile"></param>
/// <returns></returns>
public static bool AES_EncryptFile(string InputFile, string OutputFile)
{
try
{
string decryptKey = "www.iqidi.com";
FileStream fr = new FileStream(InputFile, FileMode.Open);
FileStream fren = new FileStream(OutputFile, FileMode.Create);
CryptoStream Enfr = AES_EncryptStrream(fren, decryptKey);
byte[] bytearrayinput = new byte[fr.Length];
fr.Read(bytearrayinput, 0, bytearrayinput.Length);
Enfr.Write(bytearrayinput, 0, bytearrayinput.Length);
Enfr.Close();
fr.Close();
fren.Close();
}
catch
{
//文件异常
return false;
}
return true;
}
/// <summary>
/// 对指定的文件解压缩
/// </summary>
/// <param name="InputFile"></param>
/// <param name="OutputFile"></param>
/// <returns></returns>
public static bool AES_DecryptFile(string InputFile, string OutputFile)
{
try
{
string decryptKey = "www.iqidi.com";
FileStream fr = new FileStream(InputFile, FileMode.Open);
FileStream frde = new FileStream(OutputFile, FileMode.Create);
CryptoStream Defr = AES_DecryptStream(fr, decryptKey);
byte[] bytearrayoutput = new byte[1024];
int m_count = 0;
do
{
m_count = Defr.Read(bytearrayoutput, 0, bytearrayoutput.Length);
frde.Write(bytearrayoutput, 0, m_count);
if (m_count < bytearrayoutput.Length)
break;
} while (true);
Defr.Close();
fr.Close();
frde.Close();
}
catch
{
//文件异常
return false;
}
return true;
}
#endregion
3、 Base64加密解密算法
#region Base64加密解密
/// <summary>
/// Base64是一種使用64基的位置計數法。它使用2的最大次方來代表僅可列印的ASCII 字元。
/// 這使它可用來作為電子郵件的傳輸編碼。在Base64中的變數使用字元A-Z、a-z和0-9 ，
/// 這樣共有62個字元，用來作為開始的64個數字，最後兩個用來作為數字的符號在不同的
/// 系統中而不同。
/// Base64加密
/// </summary>
/// <param name="str"></param>
/// <returns></returns>
public static string Base64Encrypt(string str)
{
byte[] encbuff = System.Text.Encoding.UTF8.GetBytes(str);
return Convert.ToBase64String(encbuff);
}
/// <summary>
/// Base64解密
/// </summary>
/// <param name="str"></param>
/// <returns></returns>
public static string Base64Decrypt(string str)
{
byte[] decbuff = Convert.FromBase64String(str);
return System.Text.Encoding.UTF8.GetString(decbuff);
}
#endregion
4、 MD5加密及验证
MD5的加密处理应用还是比较多，由于破解难度很大，基本上大型网站或者软件商，密码加密一般采用这种方式居多。
而MD5可以用来获得32、 16、8等全部部分内容加密内容，也可以获取其加密后的哈希值。
/// <summary>
/// 获得32位的MD5加密
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static string GetMD5_32(string input)
{
System.Security.Cryptography.MD5 md5 = System.Security.Cryptography.MD5.Create();
byte[] data = md5.ComputeHash(System.Text.Encoding.Default.GetBytes(input));
StringBuilder sb = new StringBuilder();
for (int i = 0; i < data.Length; i++)
{
sb.Append(data[i].ToString("x2"));
}
return sb.ToString();
}
/// <summary>
/// 获得16位的MD5加密
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static string GetMD5_16(string input)
{
return GetMD5_32(input).Substring(8, 16);
}
/// <summary>
/// 获得8位的MD5加密
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static string GetMD5_8(string input)
{
return GetMD5_32(input).Substring(8, 8);
}
/// <summary>
/// 获得4位的MD5加密
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static string GetMD5_4(string input)
{
return GetMD5_32(input).Substring(8, 4);
}
public static string MD5EncryptHash(String input)
{
MD5 md5 = new MD5CryptoServiceProvider();
//the GetBytes method returns byte array equavalent of a string
byte[] res = md5.ComputeHash(Encoding.Default.GetBytes(input), 0, input.Length);
char[] temp = new char[res.Length];
//copy to a char array which can be passed to a String constructor
Array.Copy(res, temp, res.Length);
//return the result as a string
return new String(temp);
}
5、 对文件添加MD5标签及验证
这种方式比较有趣，我也是最近才发现其中的奥妙，其实我们为了防止文件被修改，可以采用这种方式预先添加MD5码，然后在程序代码中进行验证，这样至少可以减少部分篡改的行为吧，因为只要文件有些少的修改，Md5码将会发生变化的，呵呵。
#region MD5签名验证
/// <summary>
/// 对给定文件路径的文件加上标签
/// </summary>
/// <param name="path">要加密的文件的路径</param>
/// <returns>标签的值</returns>
public static bool AddMD5(string path)
{
bool IsNeed = true;
if (CheckMD5(path)) //已进行MD5处理
IsNeed = false;
try
{
FileStream fsread = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
byte[] md5File = new byte[fsread.Length];
fsread.Read(md5File, 0, (int)fsread.Length); // 将文件流读取到Buffer中
fsread.Close();
if (IsNeed)
{
string result = MD5Buffer(md5File, 0, md5File.Length); // 对Buffer中的字节内容算MD5
byte[] md5 = System.Text.Encoding.ASCII.GetBytes(result); // 将字符串转换成字节数组以便写人到文件中
FileStream fsWrite = new FileStream(path, FileMode.Open, FileAccess.ReadWrite);
fsWrite.Write(md5File, 0, md5File.Length); // 将文件，MD5值 重新写入到文件中。
fsWrite.Write(md5, 0, md5.Length);
fsWrite.Close();
}
else
{
FileStream fsWrite = new FileStream(path, FileMode.Open, FileAccess.ReadWrite);
fsWrite.Write(md5File, 0, md5File.Length);
fsWrite.Close();
}
}
catch
{
return false;
}
return true;
}
/// <summary>
/// 对给定路径的文件进行验证
/// </summary>
/// <param name="path"></param>
/// <returns>是否加了标签或是否标签值与内容值一致</returns>
public static bool CheckMD5(string path)
{
try
{
FileStream get_file = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
byte[] md5File = new byte[get_file.Length]; // 读入文件
get_file.Read(md5File, 0, (int)get_file.Length);
get_file.Close();
string result = MD5Buffer(md5File, 0, md5File.Length - 32); // 对文件除最后32位以外的字节计算MD5，这个32是因为标签位为32位。
string md5 = System.Text.Encoding.ASCII.GetString(md5File, md5File.Length - 32, 32); //读取文件最后32位，其中保存的就是MD5值
return result == md5;
}
catch
{
return false;
}
}
/// <summary>
/// 计算文件的MD5值
/// </summary>
/// <param name="MD5File">MD5签名文件字符数组</param>
/// <param name="index">计算起始位置</param>
/// <param name="count">计算终止位置</param>
/// <returns>计算结果</returns>
private static string MD5Buffer(byte[] MD5File, int index, int count)
{
System.Security.Cryptography.MD5CryptoServiceProvider get_md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
byte[] hash_byte = get_md5.ComputeHash(MD5File, index, count);
string result = System.BitConverter.ToString(hash_byte);
result = result.Replace("-", "");
return result;
}
#endregion
6、 SHA256加密算法
/// <summary>
/// SHA256函数
/// </summary>
/// <param name="str">原始字符串</param>
/// <returns>SHA256结果(返回长度为44字节的字符串)</returns>
public static string SHA256(string str)
{
byte[] SHA256Data = Encoding.UTF8.GetBytes(str);
SHA256Managed Sha256 = new SHA256Managed();
byte[] Result = Sha256.ComputeHash(SHA256Data);
return Convert.ToBase64String(Result); //返回长度为44字节的字符串
}
7、 MD5及Base64结合加密
这种结合方式也是比较不错的算法，至少是四不像，一般分析比较困难，比较有迷惑性，就是挂羊头，卖狗肉的行为，其实Base64加密方式，也可以做的比较复杂，不一定是上面的那种解决方式的，你可以添加一些较为复杂的算法在里面的。
/// <summary>
/// 加密字符串
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static string EncryptString(string input)
{
return MD5Util.AddMD5Profix(Base64Util.Encrypt(MD5Util.AddMD5Profix(input)));
//return Base64.Encrypt(MD5.AddMD5Profix(Base64.Encrypt(input)));
}
/// <summary>
/// 解密加过密的字符串
/// </summary>
/// <param name="input"></param>
/// <param name="throwException">解密失败是否抛异常</param>
/// <returns></returns>
public static string DecryptString(string input, bool throwException)
{
string res = "";
try
{
res = input;// Base64.Decrypt(input);
if (MD5Util.ValidateValue(res))
{
return MD5Util.RemoveMD5Profix(Base64Util.Decrypt(MD5Util.RemoveMD5Profix(res)));
}
else
{
throw new Exception("字符串无法转换成功！");
}
}
catch
{
if (throwException)
{
throw;
}
else
{
return "";
}
}
}
//-----------下面是MD5Util下面的函数
/// <summary>
/// 添加MD5的前缀，便于检查有无篡改
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static string AddMD5Profix(string input)
{
return GetMD5_4(input) + input;
}
/// <summary>
/// 移除MD5的前缀
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static string RemoveMD5Profix(string input)
{
return input.Substring(4);
}
/// <summary>
/// 验证MD5前缀处理的字符串有无被篡改
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static bool ValidateValue(string input)
{
bool res = false;
if (input.Length >= 4)
{
string tmp = input.Substring(4);
if (input.Substring(0, 4) == GetMD5_4(tmp))
{
res = true;
}
}
return res;
}
如下面代码就是上面提到的Base64Util中的内容，好像算法处理还是比较麻烦，也贴出来大家研读一下吧。
/// <summary>
/// 基于Base64的加密编码，
/// 可以设置不同的密码表来获取不同的编码合解码
/// </summary>
public class Base64Util
{
public Base64Util()
{
this.InitDict();
}
protected static Base64Util s_b64 = new Base64Util();
/// <summary>
/// 使用默认的密码表加密字符串
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static string Encrypt(string input)
{
return s_b64.Encode(input);
}
/// <summary>
/// 使用默认的密码表解密字符串
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static string Decrypt(string input)
{
return s_b64.Decode(input);
}
/// <summary>
/// 获取具有标准的Base64密码表的加密类
/// </summary>
/// <returns></returns>
public static Base64Util GetStandardBase64()
{
Base64Util b64 = new Base64Util();
b64.Pad = "=";
b64.CodeTable = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
return b64;
}
protected string m_codeTable = @"ABCDEFGHIJKLMNOPQRSTUVWXYZbacdefghijklmnopqrstu_wxyz0123456789*-";
protected string m_pad = "v";
protected Dictionary<int, char> m_t1 = new Dictionary<int, char>();
protected Dictionary<char, int> m_t2 = new Dictionary<char, int>();
/// <summary>
/// 密码表
/// </summary>
public string CodeTable
{
get { return m_codeTable; }
set
{
if (value == null)
{
throw new Exception("密码表不能为null");
}
else if (value.Length < 64)
{
throw new Exception("密码表长度必须至少为64");
}
else
{
this.ValidateRepeat(value);
this.ValidateEqualPad(value, m_pad);
m_codeTable = value;
this.InitDict();
}
}
}
/// <summary>
/// 补码
/// </summary>
public string Pad
{
get { return m_pad; }
set
{
if (value == null)
{
throw new Exception("密码表的补码不能为null");
}
else if (value.Length != 1)
{
throw new Exception("密码表的补码长度必须为1");
}
else
{
this.ValidateEqualPad(m_codeTable, value);
m_pad = value;
this.InitDict();
}
}
}
/// <summary>
/// 返回编码后的字符串
/// </summary>
/// <param name="source"></param>
/// <returns></returns>
public string Encode(string source)
{
if (source == null || source == "")
{
return "";
}
else
{
StringBuilder sb = new StringBuilder();
byte[] tmp = System.Text.UTF8Encoding.UTF8.GetBytes(source);
int remain = tmp.Length % 3;
int patch = 3 - remain;
if (remain != 0)
{
Array.Resize(ref tmp, tmp.Length + patch);
}
int cnt = (int)Math.Ceiling(tmp.Length * 1.0 / 3);
for (int i = 0; i < cnt; i++)
{
sb.Append(this.EncodeUnit(tmp[i * 3], tmp[i * 3 + 1], tmp[i * 3 + 2]));
}
if (remain != 0)
{
sb.Remove(sb.Length - patch, patch);
for (int i = 0; i < patch; i++)
{
sb.Append(m_pad);
}
}
return sb.ToString();
}
}
protected string EncodeUnit(params byte[] unit)
{
int[] obj = new int[4];
obj[0] = (unit[0] & 0xfc) >> 2;
obj[1] = ((unit[0] & 0x03) << 4) + ((unit[1] & 0xf0) >> 4);
obj[2] = ((unit[1] & 0x0f) << 2) + ((unit[2] & 0xc0) >> 6);
obj[3] = unit[2] & 0x3f;
StringBuilder sb = new StringBuilder();
for (int i = 0; i < obj.Length; i++)
{
sb.Append(this.GetEC((int)obj[i]));
}
return sb.ToString();
}
protected char GetEC(int code)
{
return m_t1[code];//m_codeTable[code];
}
/// <summary>
/// 获得解码字符串
/// </summary>
/// <param name="source"></param>
/// <returns></returns>
public string Decode(string source)
{
if (source == null || source == "")
{
return "";
}
else
{
List<byte> list = new List<byte>();
char[] tmp = source.ToCharArray();
int remain = tmp.Length % 4;
if (remain != 0)
{
Array.Resize(ref tmp, tmp.Length - remain);
}
int patch = source.IndexOf(m_pad);
if (patch != -1)
{
patch = source.Length - patch;
}
int cnt = tmp.Length / 4;
for (int i = 0; i < cnt; i++)
{
this.DecodeUnit(list, tmp[i * 4], tmp[i * 4 + 1], tmp[i * 4 + 2], tmp[i * 4 + 3]);
}
for (int i = 0; i < patch; i++)
{
list.RemoveAt(list.Count - 1);
}
return System.Text.Encoding.UTF8.GetString(list.ToArray());
}
}
protected void DecodeUnit(List<byte> byteArr, params char[] chArray)
{
int[] res = new int[3];
byte[] unit = new byte[chArray.Length];
for (int i = 0; i < chArray.Length; i++)
{
unit[i] = this.FindChar(chArray[i]);
}
res[0] = (unit[0] << 2) + ((unit[1] & 0x30) >> 4);
res[1] = ((unit[1] & 0xf) << 4) + ((unit[2] & 0x3c) >> 2);
res[2] = ((unit[2] & 0x3) << 6) + unit[3];
for (int i = 0; i < res.Length; i++)
{
byteArr.Add((byte)res[i]);
}
}
protected byte FindChar(char ch)
{
int pos = m_t2[ch];//m_codeTable.IndexOf(ch);
return (byte)pos;
}
/// <summary>
/// 初始化双向哈西字典
/// </summary>
protected void InitDict()
{
m_t1.Clear();
m_t2.Clear();
m_t2.Add(m_pad[0], -1);
for (int i = 0; i < m_codeTable.Length; i++)
{
m_t1.Add(i, m_codeTable[i]);
m_t2.Add(m_codeTable[i], i);
}
}
/// <summary>
/// 检查字符串中的字符是否有重复
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
protected void ValidateRepeat(string input)
{
for (int i = 0; i < input.Length; i++)
{
if (input.LastIndexOf(input[i]) > i)
{
throw new Exception("密码表中含有重复字符：" + input[i]);
}
}
}
/// <summary>
/// 检查字符串是否包含补码字符
/// </summary>
/// <param name="input"></param>
/// <param name="pad"></param>
protected void ValidateEqualPad(string input, string pad)
{
if (input.IndexOf(pad) > -1)
{
throw new Exception("密码表中包含了补码字符：" + pad);
}
}
}
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http://www.cnblogs.com/wuhuacong/archive/2010/09/30/1839119.html