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/* base64-encode.c
*
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2002 Niels Möller
*
* 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.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include <stdlib.h>
#include "base64.h"
#define TABLE_INVALID -1
#define TABLE_SPACE -2
#define TABLE_END -3
static const signed char
decode_table[0x100] =
{
/* White space is HT, VT, FF, CR, LF and SPC */
-1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -2, -2, -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,
};
void
base64_decode_init(struct base64_decode_ctx *ctx)
{
ctx->word = ctx->bits = ctx->padding = 0;
}
int
base64_decode_single(struct base64_decode_ctx *ctx,
uint8_t *dst,
uint8_t src)
{
int data;
data = decode_table[src];
switch(data)
{
default:
assert(data >= 0 && data < 0x40);
if (ctx->padding)
return -1;
ctx->word = ctx->word << 6 | data;
ctx->bits += 6;
if (ctx->bits >= 8)
{
ctx->bits -= 8;
dst[0] = ctx->word >> ctx->bits;
return 1;
}
else return 0;
case TABLE_INVALID:
return -1;
case TABLE_SPACE:
return 0;
case TABLE_END:
/* There can be at most two padding characters. */
if (!ctx->bits || ctx->padding > 2)
return -1;
if (ctx->word & ( (1<<ctx->bits) - 1))
/* We shouldn't have any leftover bits */
return -1;
ctx->padding++;
ctx->bits -= 2;
return 0;
}
}
int
base64_decode_update(struct base64_decode_ctx *ctx,
unsigned *dst_length,
uint8_t *dst,
unsigned src_length,
const uint8_t *src)
{
unsigned done;
unsigned i;
assert(*dst_length >= BASE64_DECODE_LENGTH(src_length));
for (i = 0, done = 0; i<src_length; i++)
switch(base64_decode_single(ctx, dst + done, src[i]))
{
case -1:
return 0;
case 1:
done++;
/* Fall through */
case 0:
break;
default:
abort();
}
assert(done <= BASE64_DECODE_LENGTH(src_length));
*dst_length = done;
return 1;
}
int
base64_decode_final(struct base64_decode_ctx *ctx)
{
return ctx->bits == 0;
}
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