C#_ Encryption and decryption

First, MD5 encryption and decryption

1. Encryption

public static string ToMd5 (String clearstring)

{            byte[] clearbytes = System.Text.Encoding.Unicode.GetBytes (clearstring);            String hashedpwd = Bitconverter.tostring (((HashAlgorithm) cryptoconfig.createfromname ("MD5"). ComputeHash (clearbytes));            return hashedpwd;        }

2, 32-bit MD5 encryption

        public static string Getmd5base32 (String sInput)

        {            System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding ();            System.Security.Cryptography.MD5 MD5;            Byte[] BYTESSRC;            Byte[] result;            StringBuilder sb = new StringBuilder ();            BYTESSRC = Encoding. GetBytes (sInput);            MD5 = new System.Security.Cryptography.MD5CryptoServiceProvider ();            result = Md5.computehash (BYTESSRC);            for (int i = 0; I < result. Length; i++)            {                sb. AppendFormat ("{0:x2}", Result[i]);            }            Return SB. ToString ();        }

Second, base64 algorithm encryption and decryption

    <summary>////    for Base64 coding algorithms///    </summary> public    class Base64    {        public Base64 ()        {        }//         <summary>        encrypt string using base64 algorithm        ///</summary> <param name= "sourcestring" > Strings to be encrypted </param>//        <param name= "Ens" >system.text.encoding objects , such as creating a Chinese encoding Set object: System.Text.Encoding.GetEncoding (54936) </param>///        <returns> Overweight text string </returns > Public        static string encodingforstring (String sourcestring, System.Text.Encoding ens)        {            Return convert.tobase64string (Ens. GetBytes (sourcestring));        }

<summary>////Use the Base64 algorithm to encrypt the string///</summary>//<param name= "sourcestring" > string to be encrypted </param >///<returns> Overweight text string </returns> public static string encodingforstring (String sourcestring){return encodingforstring (sourcestring, System.Text.Encoding.GetEncoding (54936));}<summary>////restore string from Base64 encoded string, support Chinese//</summary>//<param name= "base64string" > Base64 encrypted string </param>//<param name= "Ens" >system.text.encoding object, such as creating a Chinese encoding Set object: System.Text.Encoding.GetEncoding (54936) </param>///<returns> restored text string </returns> public static string Decodingforstring (String base64string, System.Text.Encoding ens){/** * *********************************************************** * * * The In-machine code (ANSI character encoding) of the character in bytes obtained from Base64string * General, Conversion of the in-machine code to Chinese characters is the formula: * (char) (first byte binary value *256+ second byte value) * While char or string in C # is Unicode-encoded, it is not possible to calculate the * ANSI Byte-and Unicode-encoded incompatible with the above formula * Therefore, using the encoding classes provided by the. NET class library to implement conversions from ANSI encoding to Unicode code * The GetEncoding method relies on the underlying platform to support most code pages. However, system support is provided for the following scenarios: The default encoding, which is the encoding specified in the locale of the computer on which the method is executed; Little-endian Unicode (utf-16le); Big-endian Unicode (UTF-16BE); Windows Operating system (windows-1252); Utf-7;utf-8;ascii and GB18030 (Simplified Chinese). * * Specify one of the names listed in the following table to obtain the system-supported encoding with the corresponding code page. * * code page name * "Utf-16le", "utf-16", "ucs-2", "Unicode" or "iso-10646-ucs-2" * 1201 "utf-16be" or "Unicodefffe" * 1252 "windows- 1252 "* 65000" utf-7 "," Csunicode11utf7 "," unicode-1-1-utf-7 "," unicode-2-0-utf-7 "," x-unicode-1-1-utf-7 "or" X-unicode-2-0-utf-7 "* 65001" Utf-8 "," Unicode-1-1-utf-8 "," Unicode-2-0-utf-8 "," X-unicode-1-1-utf-8 "or" X-unicode-2-0-utf-8 "* 20127" Us-ascii "," Us "," ASCII "," ansi_x3.4-1968 "," ansi_x3.4-1986 "," cp367 "," Csascii "," IBM367 " , "Iso-ir-6", "iso646-us" or "iso_646.irv:1991" *54936 "GB18030" * * Some platforms may not support specific code pages. For example, the U.S. version of Windows 98 may not support the Japanese Shift-jis code page (code page 932). In this case, the GetEncoding method will raise NotSupportedException when executing the following C # code: * * Encoding enc = encoding.getencoding ("Shift-jis"); ///Get the original character return ens from Base64string. GetString (convert.frombase64string (base64string)); }<summary>////restore string from Base64 encoded string, support Chinese//</summary>//<param name= "base64string" > Base64 encrypted string </param>////<returns> restored text string </returns> public static string Decodingforstring ( String base64string){return decodingforstring (base64string, System.Text.Encoding.GetEncoding (54936));} //--------------------------------------------------------------------------------------<summary>///Base64 for any type of file///</summary>//<param name= "filename" > File path and filename </param >///<returns> base64 encoded string </returns> public static string Encodingforfile (String fileName){System.IO.FileStream fs = System.IO.File.OpenRead (FileName); System.IO.BinaryReader br = new System.IO.BinaryReader (FS);/*system.byte[] B=new System.byte[fs. Length]; Fs. Read (B,0,convert.toint32 (fs. LENGTH); */String base64string = Convert.tobase64string (Br. Readbytes ((int) fs. Length)); Br. Close (); Fs. Close (); return base64string; }<summary>////Save the Base64 encoded string as a file///</summary>//<param name= "base64string" > the string after base64 </param>//<param name= "filename" > Save file path and file name </param>//<returns> Save file successfully </returns > public static bool Savedecodingtofile (string base64string, String fileName){System.IO.FileStream fs = new System.IO.FileStream (FileName, System.IO.FileMode.Create); System.IO.BinaryWriter bw = new System.IO.BinaryWriter (FS); Bw. Write (convert.frombase64string (base64string)); Bw. Close (); Fs. Close (); return true; } //-------------------------------------------------------------------------------///<summary>///From the network address one and convert it to Base64 code///</summary>// <param name= "url" > URL address of the file, an absolute URL address </param>//<param name= "Objwebclient" > System.Net.WebClient objects </param>///<returns></returns> public static string Encodingfilefromurl ( String URL, System.Net.WebClient objwebclient) {return Convert.tobase64string (objwebclient.downloaddata (URL)); } ///<summary>///From the network address one and convert it to Base64 code///</summary>// <param name= "url" > URL address of the file, an absolute URL address </param>//<returns> Convert the file after the Base64 string </returns> public static string Encodingfilefromurl (string url) {// System.Net.WebClient mywebclient = new System.Net.WebClient (); Return Encodingfilefromurl (URL, new System.Net.WebClient ()); } }

Third, SHA1 encryption

{     {      return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile (Code, " SHA1 "). ToLower ();   }   else    {      return string. Empty;   }   } 

Iv. AES Encryption and decryption

<summary>//AES Encryption decryption///</summary> public class AES{<summary>///Get key///</summary> private static string key{Get{return @ ")        O[nb]6,yf}+efcaj{+oesb9d8>z ' e9m ';} }<summary>///Get vector//</summary> private static string IV{Get{return @ "L+/~f4,ir) B$=PKF"; } }<summary>//AES encryption///</summary>/<param name= "Plainstr" > Clear text string </param>//<returns& gt; ciphertext </returns> public static string Aesencrypt (String plainstr){byte[] bkey = Encoding.UTF8.GetBytes (Key); byte[] BIV = Encoding.UTF8.GetBytes (IV); byte[] ByteArray = Encoding.UTF8.Get Bytes (PLAINSTR); string encrypt = null; Rijndael AES = Rijndael.create (); Try{using (MemoryStream mstream = new MemoryStream ()){using (CryptoStream cstream = new CryptoStream (Mstream, AES. CreateEncryptor (Bkey, BIV), CryptoStreamMode.Write)){cstream.write (byteArray, 0, bytearray.length); Cstream.flushfinalblock (); encrypt = Convert.tobase64string ( Mstream.toarray ()); }}} catch{} aes. Clear (); return encrypt; }<summary>//AES encryption///</summary>/<param name= "Plainstr" > Clear text string </param>//<param Nam E= "Returnnull" > whether to return Null,false when encryption fails to return string.empty</param>//<returns> redaction </returns> Public static string Aesencrypt (string plainstr, bool returnnull){String encrypt = Aesencrypt (PLAINSTR); return returnnull? Encrypt: (encrypt = = null?) String.Empty:encrypt); }<summary>//AES decryption///</summary>/<param name= "Encryptstr" > Ciphertext string </param>//< returns> plaintext </returns> public static string Aesdecrypt (String encryptstr){byte[] bkey = Encoding.UTF8.GetBytes (Key); byte[] BIV = Encoding.UTF8.GetBytes (IV); byte[] ByteArray = Convert.frombase6 4String (ENCRYPTSTR); string decrypt = null; Rijndael AES = Rijndael.create (); Try{using (MemoryStream mstream = new MemoryStream ()){using (CryptoStream cstream = new CryptoStream (Mstream, AES. CreateDecryptor (Bkey, BIV), cryptostreammode.write)) {cStream.Write ( ByteArray, 0, bytearray.length); Cstream.flushfinalblock (); Decrypt = Encoding.UTF8.GetString (Mstream.toarray ()); }}} catch {} AES. Clear (); return decrypt; } ///<summary>//AES decryption//</summary>//<param name= " Encryptstr "> Ciphertext string </param>//<param name=" Returnnull "> If decryption fails return null,false return String.empty</param >//<returns> Clear text </returns> public static string Aesdecrypt (string encryptstr, bool returnnull) {String decrypt = Aesdecrypt (ENCRYPTSTR); return returnnull? Decrypt: (Decrypt = = NULL ? String.Empty:decrypt); } }

C#_ Encryption and decryption