/* * 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 #include #include "base64.h" /* Useful for encoding */ static char base64_chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; /* For constant time lookups */ static int is_base64_char(char c) { return (('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z') || ('0' <= c && c <= '9') || (c == '+' || c == '/')); } 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 ((unsigned) -1) static unsigned int token_decode(const char *token, const size_t size) { int i; unsigned int val = 0; int marker = 0; if (size < 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; unsigned int size; q = data; size = strlen(str); for (p = str; *p && (*p == '=' || is_base64_char(*p)); p += 4, size -= 4) { unsigned int val = token_decode(p, size); 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; }