122 lines
3.3 KiB
C
122 lines
3.3 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) 2006-2015 Daniel Otte (bg@nerilex.org)
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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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{
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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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{
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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)
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| ((((uint8_t*) src)[i * 3 + 1]) >> 4)) & 0x3F;
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a[2] = (((((uint8_t*) src)[i * 3 + 1]) << 2)
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| ((((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)
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| ((((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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