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/* base64.c
*
* Base64 "ASCII armor" codec.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2002 Niels Mller, Dan Egnor
*
* The nettle library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The nettle library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#include "base64.h"
#include <assert.h>
#define TABLE_INVALID -1
#define TABLE_SPACE -2
#define TABLE_END -3
static const uint8_t encode_table[64] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
static const signed char decode_table[256] =
{
-1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -3, -1, -1,
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
};
unsigned
base64_encode(uint8_t *dst,
unsigned src_length,
const uint8_t *src)
{
uint8_t *out = dst;
while (src_length >= 3)
{
*out++ = encode_table[0x3F & (src[0] >> 2)];
*out++ = encode_table[0x3F & ((src[0] << 4) | (src[1] >> 4))];
*out++ = encode_table[0x3F & ((src[1] << 2) | (src[2] >> 6))];
*out++ = encode_table[0x3F & src[2]];
src += 3;
src_length -= 3;
}
switch (src_length)
{
case 2:
*out++ = encode_table[0x3F & (src[0] >> 2)];
*out++ = encode_table[0x3F & ((src[0] << 4) | (src[1] >> 4))];
*out++ = encode_table[0x3F & (src[1] << 2)];
*out++ = '=';
break;
case 1:
*out++ = encode_table[0x3F & (src[0] >> 2)];
*out++ = encode_table[0x3F & (src[0] << 4)];
*out++ = '=';
*out++ = '=';
break;
case 0:
break;
}
return out - dst;
}
unsigned
base64_decode(uint8_t *dst,
unsigned src_length,
const uint8_t *src)
{
uint8_t *out = dst;
uint32_t accum = 0;
int shift = 10;
while (src_length > 0)
{
const int data = decode_table[*src];
switch (data)
{
default:
accum |= data << shift;
shift -= 6;
if (shift <= 2)
{
*out++ = accum >> 8;
accum = accum << 8;
shift += 8;
}
case TABLE_INVALID:
case TABLE_SPACE:
case TABLE_END:
break;
}
++src;
--src_length;
}
return out - dst;
}