Base64编解码的C++实现

//Filename: Base64.h #include <string> using namespace std; class Base64 { public: static string enBase64(const string &inbuf); static string deBase64(string src); private: static string enBase64_help(const char* inbuf, size_t inbufLen); static int deBase64_help(string src, char* outbuf); static void _enBase64Help(unsigned char chasc[3], unsigned char chuue[4]); static void _deBase64Help(unsigned char chuue[4], unsigned char chasc[3]); };

 

//Filename: Base64.cpp #include "Base64.h" string Base64::enBase64( const string &inbuf) { return Base64::enBase64_help( inbuf.c_str(), inbuf.size()); } string Base64::deBase64( string src) { char * buf = new char[src.length()*2]; int len = deBase64_help(src, buf); buf[len] = '/0'; string result = string(buf, len); delete[] buf; return result; } string Base64::enBase64_help( const char* inbuf, size_t inbufLen ) { string outStr; unsigned char in[8]; unsigned char out[8]; out[4] = 0; size_t blocks = inbufLen / 3; for ( size_t i = 0; i<blocks; i++ ) { in[0] = inbuf[i*3]; in[1] = inbuf[i*3+1]; in[2] = inbuf[i*3+2]; _enBase64Help(in, out); outStr += out[0]; outStr += out[1]; outStr += out[2]; outStr += out[3]; } if ( inbufLen % 3 == 1 ) { in[0] = inbuf[inbufLen-1]; in[1] = 0; in[2] = 0; _enBase64Help(in, out); outStr += out[0]; outStr += out[1]; outStr += '='; outStr += '='; } else if ( inbufLen % 3 == 2 ) { in[0] = inbuf[inbufLen-2]; in[1] = inbuf[inbufLen-1]; in[2] = 0; _enBase64Help(in, out); outStr += out[0]; outStr += out[1]; outStr += out[2]; outStr += '='; } return string(outStr); } int Base64::deBase64_help( string src, char* outbuf ) { if ((src.size()% 4 )!= 0 ) { return 0; } unsigned char in[4]; unsigned char out[3]; size_t blocks = src.size()/4; for ( size_t i = 0; i<blocks; i++ ) { in[0] = src[i*4]; in[1] = src[i*4+1]; in[2] = src[i*4+2]; in[3] = src[i*4+3]; _deBase64Help(in, out); outbuf[i*3] = out[0]; outbuf[i*3+1] = out[1]; outbuf[i*3+2] = out[2]; } int length = src.size()/ 4 * 3; if ( src[src.size()-1] == ' = ' ) { length--; if ( src[src.size()-2] == ' = ' ) { length--; } } return length; } void Base64::_enBase64Help(unsigned char chasc[3], unsigned char chuue[4]) { int i, k = 2; unsigned char t = 0; for ( i = 0; i<3; i++ ) { *(chuue+i) = *(chasc+i)>>k; *(chuue+i)|= t; t = *(chasc+i)<<(8-k); t >>= 2; k += 2; } *(chuue+3) = *(chasc+2)&63; for ( i = 0; i<4; i++ ) { if ( (*(chuue+i)<=128)&& (*(chuue+i)<=25)) { *(chuue+i)+= 65; } else if ( (*(chuue+i)>=26)&& (*(chuue+i)<=51)) { *(chuue+i)+= 71; } else if ( (*(chuue+i)>=52)&& (*(chuue+i)<=61)) { *(chuue+i)-= 4; } else if ( *(chuue+i)==62 ) { *(chuue+i) = 43; } else if ( *(chuue+i)==63 ) { *(chuue+i) = 47; } } } void Base64::_deBase64Help(unsigned char chuue[4], unsigned char chasc[3]) { int i,k = 2; unsigned char t = 0; for ( i = 0; i<4; i++ ) { if ( (*(chuue+i)>=65)&&(*(chuue+i)<=90) ) *(chuue+i)-= 65; else if ( (*(chuue+i)>=97)&&(*(chuue+i)<=122) ) *(chuue+i)-= 71; else if ( (*(chuue+i)>=48)&&(*(chuue+i)<=57) ) *(chuue+i)+= 4; else if ( *(chuue+i)==43 ) *(chuue+i) = 62; else if ( *(chuue+i)==47 ) *(chuue+i) = 63; else if ( *(chuue+i)==61 ) *(chuue+i) = 0; } for ( i = 0; i<3; i++ ) { *(chasc+i) = *(chuue+i)<< k; k += 2; t = *(chuue+i+1)>> (8-k); *(chasc+i)|= t; } }

 

下面对上面实现的那个Base64类进行测试：

#include "Base64.h" #include <iostream> using namespace std; int main(void) { string buf1 = "admin:admin"; string buf2 = "YWRtaW46YWRtaW4="; string r1 = Base64::enBase64(buf1); string r2 = Base64::deBase64(buf2); cout<<buf1<<"的编码后结果："<<r1<<endl; cout<<buf2<<"的解码后结果："<<r2<<endl; return 0; }

运行后的结果：

admin:admin的编码后结果：YWRtaW46YWRtaW4=
YWRtaW46YWRtaW4=的解码后结果：admin:admin