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/* base64.h
*
* "ASCII armor" codecs.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2002 Niels Möller, 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.
*/
#ifndef NETTLE_BASE64_H_INCLUDED
#define NETTLE_BASE64_H_INCLUDED
#include <inttypes.h>
/* Base64 encoding */
#define BASE64_BINARY_BLOCK_SIZE 3
#define BASE64_TEXT_BLOCK_SIZE 4
/* Overlapping source and destination is allowed, as long as the start
* of the source area is not later than the start of the destination
* area. */
unsigned /* Returns the length of encoded data */
base64_encode(uint8_t *dst,
unsigned src_length,
const uint8_t *src);
/* Precise length of encoded data (including padding) */
#define BASE64_ENCODE_LENGTH(src_length) \
((BASE64_BINARY_BLOCK_SIZE - 1 + (src_length)) \
/ BASE64_BINARY_BLOCK_SIZE * BASE64_TEXT_BLOCK_SIZE)
/* FIXME: Perhaps rename to base64_decode_ctx? */
struct base64_ctx /* Internal, do not modify */
{
uint16_t accum; /* Partial byte accumulated so far, filled msb first */
int16_t shift; /* Bitshift for the next 6-bit segment added to buffer */
};
void
base64_decode_init(struct base64_ctx *ctx);
/* Overlapping source and destination is allowed, as long as the start
* of the source area is not before the start of the destination
* area. */
unsigned /* Returns the length of decoded data */
base64_decode_update(struct base64_ctx *ctx,
uint8_t *dst,
unsigned src_length,
const uint8_t *src);
/* Maximum length of decoded data.
*
* NOTE: This size should work even for improper base 64 data. For
* example, consider an (encoded) input string of two bytes. When
* we'll generate one byte of output before noticing that the input is
* truncated. And BASE64_DECODE_LENGTH(2) == 2*3/4 == 1, so that is
* just fine. */
#define BASE64_DECODE_LENGTH(src_length) \
((src_length) * BASE64_BINARY_BLOCK_SIZE / BASE64_TEXT_BLOCK_SIZE)
#endif /* NETTLE_BASE64_H_INCLUDED */
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