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/*
* Copyright (c) 1995 - 1999 Kungliga Tekniska Högskolan
* (Royal Institute of Technology, Stockholm, Sweden).
* 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. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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.
*/
/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
The following encoding technique is taken from RFC 1521 by Borenstein
and Freed. It is reproduced here in a slightly edited form for
convenience.
A 65-character subset of US-ASCII is used, enabling 6 bits to be
represented per printable character. (The extra 65th character, "=",
is used to signify a special processing function.)
The encoding process represents 24-bit groups of input bits as output
strings of 4 encoded characters. Proceeding from left to right, a
24-bit input group is formed by concatenating 3 8-bit input groups.
These 24 bits are then treated as 4 concatenated 6-bit groups, each
of which is translated into a single digit in the base64 alphabet.
Each 6-bit group is used as an index into an array of 64 printable
characters. The character referenced by the index is placed in the
output string.
Table 1: The Base64 Alphabet
Value Encoding Value Encoding Value Encoding Value Encoding
0 A 17 R 34 i 51 z
1 B 18 S 35 j 52 0
2 C 19 T 36 k 53 1
3 D 20 U 37 l 54 2
4 E 21 V 38 m 55 3
5 F 22 W 39 n 56 4
6 G 23 X 40 o 57 5
7 H 24 Y 41 p 58 6
8 I 25 Z 42 q 59 7
9 J 26 a 43 r 60 8
10 K 27 b 44 s 61 9
11 L 28 c 45 t 62 +
12 M 29 d 46 u 63 /
13 N 30 e 47 v
14 O 31 f 48 w (pad) =
15 P 32 g 49 x
16 Q 33 h 50 y
Special processing is performed if fewer than 24 bits are available
at the end of the data being encoded. A full encoding quantum is
always completed at the end of a quantity. When fewer than 24 input
bits are available in an input group, zero bits are added (on the
right) to form an integral number of 6-bit groups. Padding at the
end of the data is performed using the '=' character.
Since all base64 input is an integral number of octets, only the
-------------------------------------------------
following cases can arise:
(1) the final quantum of encoding input is an integral
multiple of 24 bits; here, the final unit of encoded
output will be an integral multiple of 4 characters
with no "=" padding,
(2) the final quantum of encoding input is exactly 8 bits;
here, the final unit of encoded output will be two
characters followed by two "=" padding characters, or
(3) the final quantum of encoding input is exactly 16 bits;
here, the final unit of encoded output will be three
characters followed by one "=" padding character.
*/
/* $Id: base64.c,v 1.5 2001/05/28 17:33:41 joda Exp $ */
/*
* Code taken from Kerberos krb4-1.2.2
*/
#include <stdlib.h>
#include <string.h>
#include "base64.h"
static char base64_chars[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static int
pos(char c)
{
char *p;
for (p = base64_chars; *p; p++)
if (*p == c)
return p - base64_chars;
return -1;
}
int
base64_encode(const void *data, int size, char **str)
{
char *s, *p;
int i;
int c;
const unsigned char *q;
p = s = (char *) malloc(size * 4 / 3 + 4);
if (p == NULL)
return -1;
q = (const unsigned char *) data;
i = 0;
for (i = 0; i < size;)
{
c = q[i++];
c *= 256;
if (i < size)
c += q[i];
i++;
c *= 256;
if (i < size)
c += q[i];
i++;
p[0] = base64_chars[(c & 0x00fc0000) >> 18];
p[1] = base64_chars[(c & 0x0003f000) >> 12];
p[2] = base64_chars[(c & 0x00000fc0) >> 6];
p[3] = base64_chars[(c & 0x0000003f) >> 0];
if (i > size)
p[3] = '=';
if (i > size + 1)
p[2] = '=';
p += 4;
}
*p = 0;
*str = s;
return strlen(s);
}
#define DECODE_ERROR 0xffffffff
static unsigned int
token_decode(const char *token)
{
int i;
unsigned int val = 0;
int marker = 0;
if (strlen(token) < 4)
return DECODE_ERROR;
for (i = 0; i < 4; i++)
{
val *= 64;
if (token[i] == '=')
marker++;
else if (marker > 0)
return DECODE_ERROR;
else
val += pos(token[i]);
}
if (marker > 2)
return DECODE_ERROR;
return (marker << 24) | val;
}
int
base64_decode(const char *str, void *data)
{
const char *p;
unsigned char *q;
q = data;
for (p = str; *p && (*p == '=' || strchr(base64_chars, *p)); p += 4)
{
unsigned int val = token_decode(p);
unsigned int marker = (val >> 24) & 0xff;
if (val == DECODE_ERROR)
return -1;
*q++ = (val >> 16) & 0xff;
if (marker < 2)
*q++ = (val >> 8) & 0xff;
if (marker < 1)
*q++ = val & 0xff;
}
return q - (unsigned char *) data;
}
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