118 lines
2.8 KiB
C
118 lines
2.8 KiB
C
/* base64_enc.c */
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/*
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* This file is part of the AVR-Crypto-Lib.
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* Copyright (C) 2006, 2007, 2008 Daniel Otte (daniel.otte@rub.de)
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* base64 encoder (RFC3548)
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* Author: Daniel Otte
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* License: GPLv3
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*
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*
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*/
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#include <stdint.h>
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#include "base64_enc.h"
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#if 1
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#include <avr/pgmspace.h>
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const char base64_alphabet[64] PROGMEM = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3',
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'4', '5', '6', '7', '8', '9', '+', '/' };
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static
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char bit6toAscii(uint8_t a){
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a &= (uint8_t)0x3F;
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return pgm_read_byte(base64_alphabet+a);
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}
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#else
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static
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char bit6toAscii(uint8_t a){
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a &= (uint8_t)0x3F;
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if(a<=25){
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return a+'A';
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} else {
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if(a<=51){
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return a-26+'a';
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} else {
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if(a<=61){
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return a-52+'0';
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} else {
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if(a==62){
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return '+';
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} else {
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return '/'; /* a == 63 */
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}
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}
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}
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}
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}
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#endif
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void base64enc(char* dest,const void* src, uint16_t length){
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uint16_t i,j;
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uint8_t a[4];
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for(i=0; i<length/3; ++i){
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a[0]= (((uint8_t*)src)[i*3+0])>>2;
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a[1]= (((((uint8_t*)src)[i*3+0])<<4) | ((((uint8_t*)src)[i*3+1])>>4)) & 0x3F;
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a[2]= (((((uint8_t*)src)[i*3+1])<<2) | ((((uint8_t*)src)[i*3+2])>>6)) & 0x3F;
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a[3]= (((uint8_t*)src)[i*3+2]) & 0x3F;
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for(j=0; j<4; ++j){
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*dest++=bit6toAscii(a[j]);
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}
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}
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/* now we do the rest */
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switch(length%3){
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case 0:
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break;
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case 1:
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a[0]=(((uint8_t*)src)[i*3+0])>>2;
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a[1]=((((uint8_t*)src)[i*3+0])<<4)&0x3F;
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*dest++ = bit6toAscii(a[0]);
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*dest++ = bit6toAscii(a[1]);
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*dest++ = '=';
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*dest++ = '=';
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break;
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case 2:
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a[0]= (((uint8_t*)src)[i*3+0])>>2;
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a[1]= (((((uint8_t*)src)[i*3+0])<<4) | ((((uint8_t*)src)[i*3+1])>>4)) & 0x3F;
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a[2]= ((((uint8_t*)src)[i*3+1])<<2) & 0x3F;
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*dest++ = bit6toAscii(a[0]);
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*dest++ = bit6toAscii(a[1]);
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*dest++ = bit6toAscii(a[2]);
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*dest++ = '=';
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break;
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default: /* this will not happen! */
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break;
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}
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/* finalize: */
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*dest='\0';
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}
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