base64.h

/*******************************************************************************
 *
 *  /\  |  _   _  ._ o _|_ |_  ._ _   _ 
 * /--\ | (_| (_) |  |  |_ | | | | | _> 
 *         _|                      
 * 
 * Base64
 *	Base64 is a group of similar binary-to-text encoding schemes that represent 
 * binary data in an ASCII string format by translating it into a radix-64 
 * representation. The term Base64 originates from a specific MIME content 
 * transfer encoding.
 *
 * http://en.wikipedia.org/wiki/Base64
 ******************************************************************************/

#ifndef _CBASE64_H_
#define _CBASE64_H_


#include <iostream>
#include <string>
#include <string.h>

namespace alg {
	class CBase64 {
		public:
			static std::string encodeBase64(unsigned char *input , int input_len) {
				const char * code="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
				unsigned char input_char[3];
				char output_char[5];
				int output_num;
				std::string output_str="";
				int near=input_len%3;

				for (int i=0;i<input_len;i+=3) {
					memset(input_char ,0,3);
					memset(output_char ,61,5);
					if (i+3 <= input_len) {
						memcpy(input_char,input+i,3);
					} else {
						memcpy(input_char,input+i,input_len-i);
						output_num=((int)input_char[0]<<16)+((int)input_char[1]<<8)+(int)input_char[2];

						if (near==1) {
							output_char[0]=code[((output_num>>18) & 0xff)];
							output_char[1]=code[((output_num>>12) & 0x3f)];
							output_char[2]='=';
							output_char[3]='=';
							output_char[4]='\0';
						}

						if (near==2) {
							output_char[0]=code[((output_num>>18) & 0xff)];
							output_char[1]=code[((output_num>>12) & 0x3f)];
							output_char[2]=code[((output_num>>6) & 0x3f)];;
							output_char[3]='=';
							output_char[4]='\0';
						}

						output_str.append(output_char);
						break;
					}

					output_num=((int)input_char[0]<<16)+((int)input_char[1]<<8)+(int)input_char[2];
					output_char[0]=code[((output_num>>18) & 0xff)];
					output_char[1]=code[((output_num>>12) & 0x3f)];
					output_char[2]=code[((output_num>>6) & 0x3f)];
					output_char[3]=code[((output_num) & 0x3f)];
					output_char[4]='\0';
					output_str.append(output_char);
				}

				return output_str;
			}

			static std::string decodeBase64(std::string input) {
				unsigned char input_char[4];
				unsigned char output_char[4];
				int output_num=0;
				int k=0;
				std::string output_str="";

				for (unsigned int i=0;i<input.size();i++) {
					input_char[k]=indexOfCode(input[i]);
					k++;
					if (k==4) {
						output_num= ((int)input_char[0]<<18)+((int)input_char[1]<<12)+((int)input_char[2]<<6)+((int)input_char[3]);
						output_char[0]=(unsigned char)((output_num & 0x00FF0000 )>> 16) ;
						output_char[1]=(unsigned char)((output_num & 0x0000FF00 ) >> 8) ;
						output_char[2]=(unsigned char)(output_num & 0x000000FF) ;
						output_char[3]='\0';
						output_str.append((char *)output_char);
						k=0;
					}
				}

				return output_str;
			}

			static int indexOfCode(const char c) {
				const char * code="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
				for (unsigned int i=0;i<64;i++) {
					if (code[i]==c)
						return i;
				}
				return 0;
			}
	};
}

#endif