c++如何实现Base64算法
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2022-04-25 12:19:02
base64用途1.用于对soho级路由器(网关设备)管理员帐户密码的加密2.流媒体网站对于播放的流媒体文件的路径的加密3.迅雷等下载软件对下载链接地址的加密base64算法base64编码要求把3个...
base64用途
1.用于对soho级路由器(网关设备)管理员帐户密码的加密
2.流媒体网站对于播放的流媒体文件的路径的加密
3.迅雷等下载软件对下载链接地址的加密
base64算法
base64编码要求把3个8位字节(3*8=24)转化为4个6位的字节(4*6=24),之后在6位的前面补两个0,形成8位一个字节的形式。
base64类
函数:
unsigned int creatematchingencodingbuffer (unsigned int p_inputbytecount, char** p_ppencodingbuffer);
创建匹配于编码的缓存空间。参数:1输入字节数,2进行编码需要的缓存空间;返回值:缓存空间大小。
unsigned int creatematchingdecodingbuffer (char* p_pinputbufferstring, char** p_ppdecodingbuffer);
创建匹配于解码的缓存空间。参数:1解码对象缓存,2进行解码需要的缓存空间;返回值:缓存空间大小。
void encodebuffer (char* p_pinputbuffer, unsigned int p_inputbufferlength, char* p_poutputbufferstring);
进行编码。参数:1明文,2明文长度,3密文输出。
unsigned int decodebuffer (char* p_pinputbufferstring, char* p_poutputbuffer);
进行解码。参数:1密文,2明文;返回值:明文长度
c++实现:
头文件:
view code /************************************************ * * * cbase64.h * * base 64 de- and encoding class * * * * ============================================ * * * * this class was written on 28.05.2003 * * by jan raddatz [jan-raddatz@web.de] * * * * ============================================ * * * * copyright (c) by jan raddatz * * this class was published @ codeguru.com * * 28.05.2003 * * * ************************************************/ #pragma once #include <afx.h> #include <stdlib.h> #include <math.h> #include <memory.h> const static unsigned int max_line_length = 76; const static char base64_alphabet [64] = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', // 0 - 9 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', // 10 - 19 'u', 'v', 'w', 'x', 'y', 'z', 'a', 'b', 'c', 'd', // 20 - 29 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', // 30 - 39 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', // 40 - 49 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', // 50 - 59 '8', '9', '+', '/' // 60 - 63 }; const static char base64_dealphabet [128] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0 - 9 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 10 - 19 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20 - 29 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 30 - 39 0, 0, 0, 62, 0, 0, 0, 63, 52, 53, // 40 - 49 54, 55, 56, 57, 58, 59, 60, 61, 0, 0, // 50 - 59 0, 61, 0, 0, 0, 0, 1, 2, 3, 4, // 60 - 69 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 70 - 79 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 80 - 89 25, 0, 0, 0, 0, 0, 0, 26, 27, 28, // 90 - 99 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // 100 - 109 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, // 110 - 119 49, 50, 51, 0, 0, 0, 0, 0 // 120 - 127 }; enum { unable_to_open_input_file, unable_to_open_output_file, unable_to_create_outputbuffer }; class cbase64 { public: cbase64 (); unsigned int calculaterecquiredencodeoutputbuffersize (unsigned int p_inputbytecount); unsigned int calculaterecquireddecodeoutputbuffersize (char* p_pinputbufferstring); void encodebytetriple (char* p_pinputbuffer, unsigned int inputcharacters, char* p_poutputbuffer); unsigned int decodebytequartet (char* p_pinputbuffer, char* p_poutputbuffer); void encodebuffer (char* p_pinputbuffer, unsigned int p_inputbufferlength, char*p_poutputbufferstring); unsigned int decodebuffer (char* p_pinputbufferstring, char* p_poutputbuffer); unsigned int creatematchingencodingbuffer (unsigned int p_inputbytecount, char** p_ppencodingbuffer); unsigned int creatematchingdecodingbuffer (char* p_pinputbufferstring, char** p_ppdecodingbuffer); unsigned int encodefile (char* p_psourcefilename, char* p_pencodedfilename); unsigned int decodefile (char* p_psourcefilename, char* p_pdecodedfilename); };
cpp文件:
view code /************************************************ * * * cbase64.cpp * * base 64 de- and encoding class * * * * ============================================ * * * * this class was written on 28.05.2003 * * by jan raddatz [jan-raddatz@web.de] * * * * ============================================ * * * * copyright (c) by jan raddatz * * this class was published @ codeguru.com * * 28.05.2003 * * * ************************************************/ #include "stdafx.h" #include "cbase64.h" cbase64::cbase64 () { } unsigned int cbase64::calculaterecquiredencodeoutputbuffersize (unsigned int p_inputbytecount) { div_t result = div (p_inputbytecount, 3); unsigned int recquiredbytes = 0; if (result.rem == 0) { // number of encoded characters recquiredbytes = result.quot * 4; // crlf -> "\r\n" each 76 characters result = div (recquiredbytes, 76); recquiredbytes += result.quot * 2; // terminating null for the encoded string recquiredbytes += 1; return recquiredbytes; } else { // number of encoded characters recquiredbytes = result.quot * 4 + 4; // crlf -> "\r\n" each 76 characters result = div (recquiredbytes, 76); recquiredbytes += result.quot * 2; // terminating null for the encoded string recquiredbytes += 1; return recquiredbytes; } } unsigned int cbase64::calculaterecquireddecodeoutputbuffersize (char* p_pinputbufferstring) { unsigned int bufferlength = strlen (p_pinputbufferstring); div_t result = div (bufferlength, 4); if (p_pinputbufferstring [bufferlength - 1] != '=') { return result.quot * 3; } else { if (p_pinputbufferstring [bufferlength - 2] == '=') { return result.quot * 3 - 2; } else { return result.quot * 3 - 1; } } } void cbase64::encodebytetriple (char* p_pinputbuffer, unsigned int inputcharacters, char* p_poutputbuffer) { unsigned int mask = 0xfc000000; unsigned int buffer = 0; char* temp = (char*) &buffer; temp [3] = p_pinputbuffer [0]; if (inputcharacters > 1) temp [2] = p_pinputbuffer [1]; if (inputcharacters > 2) temp [1] = p_pinputbuffer [2]; switch (inputcharacters) { case 3: { p_poutputbuffer [0] = base64_alphabet [(buffer & mask) >> 26]; buffer = buffer << 6; p_poutputbuffer [1] = base64_alphabet [(buffer & mask) >> 26]; buffer = buffer << 6; p_poutputbuffer [2] = base64_alphabet [(buffer & mask) >> 26]; buffer = buffer << 6; p_poutputbuffer [3] = base64_alphabet [(buffer & mask) >> 26]; break; } case 2: { p_poutputbuffer [0] = base64_alphabet [(buffer & mask) >> 26]; buffer = buffer << 6; p_poutputbuffer [1] = base64_alphabet [(buffer & mask) >> 26]; buffer = buffer << 6; p_poutputbuffer [2] = base64_alphabet [(buffer & mask) >> 26]; p_poutputbuffer [3] = '='; break; } case 1: { p_poutputbuffer [0] = base64_alphabet [(buffer & mask) >> 26]; buffer = buffer << 6; p_poutputbuffer [1] = base64_alphabet [(buffer & mask) >> 26]; p_poutputbuffer [2] = '='; p_poutputbuffer [3] = '='; break; } } } unsigned int cbase64::decodebytequartet (char* p_pinputbuffer, char* p_poutputbuffer) { unsigned int buffer = 0; if (p_pinputbuffer[3] == '=') { if (p_pinputbuffer[2] == '=') { buffer = (buffer | base64_dealphabet [p_pinputbuffer[0]]) << 6; buffer = (buffer | base64_dealphabet [p_pinputbuffer[1]]) << 6; buffer = buffer << 14; char* temp = (char*) &buffer; p_poutputbuffer [0] = temp [3]; return 1; } else { buffer = (buffer | base64_dealphabet [p_pinputbuffer[0]]) << 6; buffer = (buffer | base64_dealphabet [p_pinputbuffer[1]]) << 6; buffer = (buffer | base64_dealphabet [p_pinputbuffer[2]]) << 6; buffer = buffer << 8; char* temp = (char*) &buffer; p_poutputbuffer [0] = temp [3]; p_poutputbuffer [1] = temp [2]; return 2; } } else { buffer = (buffer | base64_dealphabet [p_pinputbuffer[0]]) << 6; buffer = (buffer | base64_dealphabet [p_pinputbuffer[1]]) << 6; buffer = (buffer | base64_dealphabet [p_pinputbuffer[2]]) << 6; buffer = (buffer | base64_dealphabet [p_pinputbuffer[3]]) << 6; buffer = buffer << 2; char* temp = (char*) &buffer; p_poutputbuffer [0] = temp [3]; p_poutputbuffer [1] = temp [2]; p_poutputbuffer [2] = temp [1]; return 3; } return -1; } void cbase64::encodebuffer(char* p_pinputbuffer, unsigned int p_inputbufferlength, char* p_poutputbufferstring) { unsigned int finishedbytequartetsperline = 0; unsigned int inputbufferindex = 0; unsigned int outputbufferindex = 0; memset (p_poutputbufferstring, 0, calculaterecquiredencodeoutputbuffersize (p_inputbufferlength)); while (inputbufferindex < p_inputbufferlength) { if (p_inputbufferlength - inputbufferindex <= 2) { finishedbytequartetsperline ++; encodebytetriple (p_pinputbuffer + inputbufferindex, p_inputbufferlength - inputbufferindex, p_poutputbufferstring + outputbufferindex); break; } else { finishedbytequartetsperline++; encodebytetriple (p_pinputbuffer + inputbufferindex, 3, p_poutputbufferstring + outputbufferindex); inputbufferindex += 3; outputbufferindex += 4; } if (finishedbytequartetsperline == 19) { p_poutputbufferstring [outputbufferindex ] = '\r'; p_poutputbufferstring [outputbufferindex+1] = '\n'; p_poutputbufferstring += 2; finishedbytequartetsperline = 0; } } } unsigned int cbase64::decodebuffer (char* p_pinputbufferstring, char* p_poutputbuffer) { unsigned int inputbufferindex = 0; unsigned int outputbufferindex = 0; unsigned int inputbufferlength = strlen (p_pinputbufferstring); char bytequartet [4]; while (inputbufferindex < inputbufferlength) { for (int i = 0; i < 4; i++) { bytequartet [i] = p_pinputbufferstring [inputbufferindex]; // ignore all characters except the ones in base64_alphabet if ((bytequartet [i] >= 48 && bytequartet [i] <= 57) || (bytequartet [i] >= 65 && bytequartet [i] <= 90) || (bytequartet [i] >= 97 && bytequartet [i] <= 122) || bytequartet [i] == '+' || bytequartet [i] == '/' || bytequartet [i] == '=') { } else { // invalid character i--; } inputbufferindex++; } outputbufferindex += decodebytequartet (bytequartet, p_poutputbuffer + outputbufferindex); } // outputbufferindex gives us the next position of the next decoded character // inside our output buffer and thus represents the number of decoded characters // in our buffer. return outputbufferindex; } unsigned int cbase64::creatematchingencodingbuffer (unsigned int p_inputbytecount, char** p_ppencodingbuffer) { unsigned int size = calculaterecquiredencodeoutputbuffersize (p_inputbytecount); (*p_ppencodingbuffer) = (char*) malloc (size); memset (*p_ppencodingbuffer, 0, size); return size; } unsigned int cbase64::creatematchingdecodingbuffer (char* p_pinputbufferstring, char** p_ppdecodingbuffer) { unsigned int size = calculaterecquireddecodeoutputbuffersize (p_pinputbufferstring); (*p_ppdecodingbuffer) = (char*) malloc (size+1); memset (*p_ppdecodingbuffer, 0, size+1); return size+1; } unsigned int cbase64::encodefile (char* p_psourcefilename, char* p_pencodedfilename) { cfile inputfile; cfile outputfile; if (!inputfile.open (p_psourcefilename, cfile::moderead)) return unable_to_open_input_file; if (!outputfile.open (p_pencodedfilename, cfile::modecreate|cfile::modewrite)) return unable_to_open_output_file; char inputbuffer [19 * 3]; char* poutputbuffer; creatematchingencodingbuffer (sizeof (inputbuffer), &poutputbuffer); if (poutputbuffer == 0) return unable_to_create_outputbuffer; unsigned int readbytes = 0; while ((readbytes = inputfile.read (inputbuffer, sizeof (inputbuffer))) != 0) { encodebuffer (inputbuffer, readbytes, poutputbuffer); outputfile.write (poutputbuffer, strlen (poutputbuffer)); } outputfile.flush (); outputfile.close (); inputfile.close (); return 0; } unsigned int cbase64::decodefile (char* p_psourcefilename, char* p_pdecodedfilename) { cstdiofile inputfile; cfile outputfile; if (!inputfile.open (p_psourcefilename, cfile::moderead)) return unable_to_open_input_file; if (!outputfile.open (p_pdecodedfilename, cfile::modecreate|cfile::modewrite)) return unable_to_open_output_file; cstring inputbuffer; char outputbuffer[64]; unsigned int readbytes = 0; while ((readbytes = inputfile.readstring (inputbuffer)) != 0) { inputbuffer.remove ('\r'); inputbuffer.remove ('\n'); unsigned int decodedbytes = decodebuffer ((lptstr) (lpctstr) inputbuffer, outputbuffer); outputfile.write (&outputbuffer [0], decodedbytes); } outputfile.flush (); outputfile.close (); inputfile.close (); return 0; }
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