base64소스

** PC에서 보셔야 잘보입니다..

/*
Base64는 바이너리 데이터를 아스키 텍스트로 변환하거나, 
그의 반대로 변환하는 인코딩 방법으로서, MIME에 의해 
 사용되는 방법들 중 하나이다. 

Base64의 경우는 8비트 문자 3개를 모아 24비트를 만들고,
이것을 6비트씩 쪼개 각각이 0x00..0x3F의 범위에 있도록 한다.
그 각각을 아래와 같은 규칙으로 변환하여 4개의 7비트 문자로 변환한다. 

0x00..0x19 ==> 'A'..'Z' 
 0x1A..0x33 ==> 'a'..'z' 
 0x34..0x3D ==> '0'..'9' 
 0x3E ==> '+' 
 0x3F ==> '/' 

만약 주어진 문자열이 정확히 24비트의 배수가 아니면 뒤에 '=' 를 덧붙인다. 
BASE64로 "안녕하세요"를 변환하면 

vsiz58fPvLy/5A==   와 같이 변환된다. 
 */

#include <stdio.h> #include <stdlib.h> #include <math.h> #include <string.h> /*------ Base64 Encoding Table ------*/ static const char MimeBase64[] = { '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', '+', '/' }; /*------ Base64 Decoding Table ------*/ static int DecodeMimeBase64[256] = { -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, /* 00-0F */ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, /* 10-1F */ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,62,-1,-1,-1,63, /* 20-2F */ 52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-1,-1,-1, /* 30-3F */ -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14, /* 40-4F */ 15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1, /* 50-5F */ -1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40, /* 60-6F */ 41,42,43,44,45,46,47,48,49,50,51,-1,-1,-1,-1,-1, /* 70-7F */ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, /* 80-8F */ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, /* 90-9F */ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, /* A0-AF */ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, /* B0-BF */ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, /* C0-CF */ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, /* D0-DF */ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, /* E0-EF */ -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1 /* F0-FF */ }; int base64_decode(char *text, unsigned char *dst, int numBytes) { const char* cp; int space_idx = 0, phase; int d, prev_d = 0; unsigned char c; space_idx = 0; phase = 0; for ( cp = text; *cp != '\0'; ++cp ) { d = DecodeMimeBase64[(int) *cp]; if ( d != -1 ) { switch ( phase ) { case 0: ++phase; break; case 1: c = ( ( prev_d << 2 ) | ( ( d & 0x30 ) >> 4 ) ); if ( space_idx < numBytes ) dst[space_idx++] = c; ++phase; break; case 2: c = ( ( ( prev_d & 0xf ) << 4 ) | ( ( d & 0x3c ) >> 2 ) ); if ( space_idx < numBytes ) dst[space_idx++] = c; ++phase; break; case 3: c = ( ( ( prev_d & 0x03 ) << 6 ) | d ); if ( space_idx < numBytes ) dst[space_idx++] = c; phase = 0; break; } prev_d = d; } } return space_idx; } int base64_encode(char *text, int numBytes, char **encodedText) { unsigned char input[3] = {0,0,0}; unsigned char output[4] = {0,0,0,0}; int index, i, j, size; char *p, *plen; plen = text + numBytes - 1; size = (4 * (numBytes / 3)) + (numBytes % 3? 4 : 0) + 1; (*encodedText) = malloc(size); j = 0; for (i = 0, p = text;p <= plen; i++, p++) { index = i % 3; input[index] = *p; if (index == 2 || p == plen) { output[0] = ((input[0] & 0xFC) >> 2); output[1] = ((input[0] & 0x3) << 4) | ((input[1] & 0xF0) >> 4); output[2] = ((input[1] & 0xF) << 2) | ((input[2] & 0xC0) >> 6); output[3] = (input[2] & 0x3F); (*encodedText)[j++] = MimeBase64[output[0]]; (*encodedText)[j++] = MimeBase64[output[1]]; (*encodedText)[j++] = index == 0? '=' : MimeBase64[output[2]]; (*encodedText)[j++] = index < 2? '=' : MimeBase64[output[3]]; input[0] = input[1] = input[2] = 0; } } (*encodedText)[j] = '\0'; return 0; } int main(int argc, char *argv[]) { int i, len; char *cpStr = "ok1234"; char *encoded[10]; base64_encode(cpStr, strlen(cpStr), encoded); printf("%s\n", *encoded); return 0; }