C # base64 Encryption Class. It can be used to change post to get to pass data.

Implement algorithms by yourself Method 1: ///<summary> /// Base64 Encryption ///</summary> ///<paramname="Message"></param> ///<returns></returns> publicstringBase64Code(stringMessage) { char []Base64Code=newchar[]{ ‘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‘ , ‘+‘ , ‘/‘ , ‘=‘ }; byteempty=( byte )0; System.Collections.ArrayListbyteMessage=newSystem.Collections.ArrayList(System.Text.Encoding.Default.GetBytes(Message)); System.Text.StringBuilderoutmessage; intmessageLen=byteMessage.Count; // Divide the character into three bytes. If the character is not enough, the character is filled with 0. intpage=messageLen/3; intuse=0; if ((use=messageLen%3)>0) { for (inti=0;i<3-use;i++) byteMessage.Add(empty); page++; } // Convert each character group of three bytes into a group of four bytes. Three in one group. One group is changed to four bytes in one group. // The method is to convert the data into ASCII codes, arrange the 24-bit data in order, and then divide the 24-bit data into 4 groups, that is, 6-bit data in each group. Add two zeros before the highest bits in each group to make up one byte. outmessage=newSystem.Text.StringBuilder(page*4); for (inti=0;i<page;i++) { // Obtains a group of three bytes. byte []instr=newbyte[3]; instr[0]=( byte )byteMessage[i*3]; instr[1]=( byte )byteMessage[i*3+1]; instr[2]=( byte )byteMessage[i*3+2]; // Six digits are in one group, and 0 is supplemented to 4 bytes. int []outstr=newint[4]; // The first output byte: Take the first six digits of the first input byte, and add 0 at the top to change it to eight digits (one byte) outstr[0]=instr[0]>>2; // Second output byte: Take the first two digits of the first input byte and the first four digits of the second input byte (6 digits in total), and add 0 at the high position, change it to 8 bits (one byte) outstr[1]=((instr[0]&0x03)<<4)^(instr[1]>>4); // The third output byte: Take the last 4 bits of the second input byte and the first 2 bits of the third input byte (6 bits in total), and add 0 at the high position, change it to 8 bits (one byte) if (!instr[1].Equals(empty)) outstr[2]=((instr[1]&0x0f)<<2)^(instr[2]>>6); else outstr[2]=64; // The fourth output byte: Take the last 6 digits of the third input byte, and add 0 at the top to change it to 8 bits (one byte) 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]]); } returnoutmessage.ToString(); } ///<summary> /// Base64 decryption ///</summary> ///<paramname="Message"></param> ///<returns></returns> publicstringBase64Decode(stringMessage) { if ((Message.Length%4)!=0) { thrownewArgumentException( "Incorrect base64 encoding. Please check. " , "Message" ); } if (!System.Text.RegularExpressions.Regex.IsMatch(Message, "^[A-Z0-9/+=]*$" ,System.Text.RegularExpressions.RegexOptions.IgnoreCase)) { thrownewArgumentException( "Contains incorrect base64 encoding. Please check. " , "Message" ); } stringBase64Code= "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=" ; intpage=Message.Length/4; System.Collections.ArrayListoutMessage=newSystem.Collections.ArrayList(page*3); char []message=Message.ToCharArray(); for (inti=0;i<page;i++) { byte []instr=newbyte[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=newbyte[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" )); returnSystem.Text.Encoding.Default.GetString(outbyte); } Directly use library functions in. net Method 2: ///<summary> /// Base64 Encryption ///</summary> ///<paramname="Message"></param> ///<returns></returns> publicstringBase64Code(stringMessage) { byte []bytes=Encoding.Default.GetBytes(Message); returnConvert.ToBase64String(bytes); } ///<summary> /// Base64 decryption ///</summary> ///<paramname="Message"></param> ///<returns></returns> publicstringBase64Decode(stringMessage) { byte []bytes=Convert.FromBase64String(Message); returnEncoding.Default.GetString(bytes); }   Reference (1)