Refer to: http://en.wikipedia.org/wiki/Base64
Base64 Content-Transfer-Encoding ( RFC2045 ) 可对任何文件进行base64 编解码，主要用于MIME邮件内容编解码
// 11111100 0xFC // 11000000 0x3 // 11110000 0xF0 // 00001111 0xF // 11000000 0xC0 // 00111111 0x3F
byte *lmMimeEncodeBase64(const byte *octetSource, int size) { byte *m_Base64_Table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int base64size = (((((size) + 2) / 3) * 4) + 1) / 76 * 78 + 78; //add "/r/n" for each line'
byte *strEncode = (byte *)MALLOC(base64size); byte cTemp[4];
//By RFC2045 --The encoded output stream must be represented in lines of no more than 76 characters each int LineLength=0; int i, len, j=0;
MEMSET(strEncode, 0, base64size);
for(i=0; i<size; i+=3) { MEMSET(cTemp,0,4);
//cTemp[0]=octetSource[i]; //cTemp[1]=octetSource[i+1]; //cTemp[2]=octetSource[i+2];
//len=strlen((char *)cTemp);
if(i<size-3){ len = 3; cTemp[0]=octetSource[i]; cTemp[1]=octetSource[i+1]; cTemp[2]=octetSource[i+2]; } else{ len = 0; if(i<size){ cTemp[0]=octetSource[i]; ++len; } if(i<size-1){ cTemp[1]=octetSource[i+1]; ++len; } if(i<size-2){ cTemp[2]=octetSource[i+2]; ++len; } //DBGPRINTF("temp[0] = %d", cTemp[0]); //DBGPRINTF("temp[1] = %d", cTemp[1]); //DBGPRINTF("temp[2] = %d", cTemp[2]); //DBGPRINTF("strEncode[0] = %d", ((int)cTemp[0] & 0xFC)>>2); //DBGPRINTF("strEncode[1] = %d", ((int)cTemp[0] & 0x3)<<4 | ((int)cTemp[1] & 0xF0)>>4); //DBGPRINTF("strEncode[2] = %d", ((int)cTemp[1] & 0xF)<<2 | ((int)cTemp[2] & 0xC0)>>6); //DBGPRINTF("strEncode[3] = %d", (int)cTemp[2] & 0x3F); //DBGPRINTF("strEncode[0] = %c", m_Base64_Table[((int)cTemp[0] & 0xFC)>>2]); //DBGPRINTF("strEncode[1] = %c", m_Base64_Table[((int)cTemp[0] & 0x3)<<4 | ((int)cTemp[1] & 0xF0)>>4]); //DBGPRINTF("strEncode[2] = %c", m_Base64_Table[((int)cTemp[1] & 0xF)<<2 | ((int)cTemp[2] & 0xC0)>>6]); //DBGPRINTF("strEncode[3] = %c", m_Base64_Table[(int)cTemp[2] & 0x3F]); }
if(len==3) { strEncode[j++] = m_Base64_Table[((int)cTemp[0] & 0xFC)>>2]; strEncode[j++] = m_Base64_Table[((int)cTemp[0] & 0x3)<<4 | ((int)cTemp[1] & 0xF0)>>4]; strEncode[j++] = m_Base64_Table[((int)cTemp[1] & 0xF)<<2 | ((int)cTemp[2] & 0xC0)>>6]; strEncode[j++] = m_Base64_Table[(int)cTemp[2] & 0x3F]; LineLength+=4; if(LineLength>=76) {strEncode[j++]='/r'; strEncode[j++]='/n'; LineLength=0;} } else if(len==2) { strEncode[j++] = m_Base64_Table[((int)cTemp[0] & 0xFC)>>2]; strEncode[j++] = m_Base64_Table[((int)cTemp[0] & 0x3 )<<4 | ((int)cTemp[1] & 0xF0 )>>4]; strEncode[j++] = m_Base64_Table[((int)cTemp[1] & 0x0F)<<2]; strEncode[j++] = '='; LineLength+=4; if(LineLength>=76) {strEncode[j++]='/r'; strEncode[j++]='/n'; LineLength=0;} } else if(len==1) { strEncode[j++] = m_Base64_Table[((int)cTemp[0] & 0xFC)>>2]; strEncode[j++] = m_Base64_Table[((int)cTemp[0] & 0x3 )<<4]; strEncode[j++] = '='; strEncode[j++] = '='; LineLength+=4; if(LineLength>=76) {strEncode[j++]='/r'; strEncode[j++]='/n'; LineLength=0;} } memset(cTemp,0,4); } //strEncode[j] = '/0'; //DBGPRINTF("--finished encode base64size = %d, j = %d", base64size, j); //for(i=j; i<base64size; i++){ // DBGPRINTF("--rest char is: %c", strEncode[i]); //} return strEncode; }
byte GetBase64Value(char ch) { if ((ch >= 'A') && (ch <= 'Z')) return ch - 'A'; if ((ch >= 'a') && (ch <= 'z')) return ch - 'a' + 26; if ((ch >= '0') && (ch <= '9')) return ch - '0' + 52; switch (ch) { case '+': return 62; case '/': return 63; case '=': /* base64 padding */ return 0; default: return 0; } }
byte *lmMimeDecodeBase64(const byte *strSource, int *psize) { byte *m_Base64_Table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; int i, j, k, size = STRLEN((char *)strSource); int n = 0; //return value byte *octetDecode = (byte *)MALLOC( (((size) - 1) / 4) *3 ); byte cTemp[5]; int Length=0; int asc[4]; for(i=0;i<size;i+=4) { MEMSET(cTemp,0,5);
cTemp[0]=strSource[i]; cTemp[1]=strSource[i+1]; cTemp[2]=strSource[i+2]; cTemp[3]=strSource[i+3];
Length+=4; if(Length==76) { i+=2; Length=0; }
for(j=0;j<4;j++) { //if(cTemp[j]=='='){ // asc[j]=0; //}else{ for(k=0;k<(int)STRLEN((char *)m_Base64_Table);k++) { if(cTemp[j]==m_Base64_Table[k]) asc[j]=k; } //} } if('='==cTemp[2] && '='==cTemp[3]) { octetDecode[n++] = (byte)(int)(asc[0] << 2 | asc[1] << 2 >> 6); } else if('='==cTemp[3]) { octetDecode[n++] = (byte)(int)(asc[0] << 2 | asc[1] << 2 >> 6); octetDecode[n++] = (byte)(int)(asc[1] << 4 | asc[2] << 2 >> 4); } else { octetDecode[n++] = (byte)(int)(asc[0] << 2 | asc[1] << 2 >> 6); octetDecode[n++] = (byte)(int)(asc[1] << 4 | asc[2] << 2 >> 4); octetDecode[n++] = (byte)(int)(asc[2] << 6 | asc[3] << 2 >> 2); }
//cTemp[0] = GetBase64Value((char)strSource[i]); //cTemp[1] = GetBase64Value((char)strSource[i+1]); //cTemp[2] = GetBase64Value((char)strSource[i+2]); //cTemp[3] = GetBase64Value((char)strSource[i+3]);
//Length+=4; //if(Length==76) //{ // i+=2; // Length=0; //}
//octetDecode[n++] = (cTemp[0] << 2) | (cTemp[1] >> 4); //octetDecode[n++] = (cTemp[1] << 4) | (cTemp[2] >> 2); //octetDecode[n++] = (cTemp[2] << 6) | (cTemp[3]);
} *psize = n; return octetDecode; }