cryb-to/lib/enc/cryb_base64_encode.c
2017-08-23 13:19:59 +02:00

85 lines
2.7 KiB
C

/*-
* Copyright (c) 2013-2014 The University of Oslo
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "cryb/impl.h"
#include <errno.h>
#include <stddef.h>
#include <stdint.h>
#include <cryb/rfc4648.h>
static const char b64enc[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
/*
* Encode data in RFC 4648 base 64 representation. The target buffer must
* have room for base64_enclen(len) characters and a terminating NUL.
*/
int
base64_encode(const uint8_t *in, size_t ilen, char *out, size_t *olen)
{
uint32_t bits;
if (*olen <= base64_enclen(ilen)) {
*olen = base64_enclen(ilen) + 1;
errno = ENOSPC;
return (-1);
}
*olen = base64_enclen(ilen) + 1;
while (ilen >= 3) {
bits = 0;
bits |= (uint32_t)*in++ << 16;
bits |= (uint32_t)*in++ << 8;
bits |= (uint32_t)*in++;
ilen -= 3;
*out++ = b64enc[bits >> 18 & 0x3f];
*out++ = b64enc[bits >> 12 & 0x3f];
*out++ = b64enc[bits >> 6 & 0x3f];
*out++ = b64enc[bits & 0x3f];
}
if (ilen > 0) {
bits = 0;
switch (ilen) {
case 2:
bits |= (uint32_t)in[1] << 8;
case 1:
bits |= (uint32_t)in[0] << 16;
CRYB_NO_DEFAULT_CASE;
}
*out++ = b64enc[bits >> 18 & 0x3f];
*out++ = b64enc[bits >> 12 & 0x3f];
*out++ = ilen > 1 ? b64enc[bits >> 6 & 0x3f] : '=';
*out++ = '=';
}
*out++ = '\0';
return (0);
}