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/*++
/* NAME
/* base32_code 3
/* SUMMARY
/* encode/decode data, base 32 style
/* SYNOPSIS
/* #include <base32_code.h>
/*
/* VSTRING *base32_encode(result, in, len)
/* VSTRING *result;
/* const char *in;
/* ssize_t len;
/*
/* VSTRING *base32_decode(result, in, len)
/* VSTRING *result;
/* const char *in;
/* ssize_t len;
/* DESCRIPTION
/* base32_encode() takes a block of len bytes and encodes it as one
/* null-terminated string. The result value is the result argument.
/*
/* base32_decode() performs the opposite transformation. The result
/* value is the result argument. The result is null terminated, whether
/* or not that makes sense.
/* DIAGNOSTICS
/* base32_decode() returns a null pointer when the input contains
/* characters not in the base 32 alphabet.
/* SEE ALSO
/* RFC 4648; padding is strictly enforced
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include "sys_defs.h"
#include <ctype.h>
#include <string.h>
#include <limits.h>
#ifndef UCHAR_MAX
#define UCHAR_MAX 0xff
#endif
/* Utility library. */
#include <msg.h>
#include <mymalloc.h>
#include <vstring.h>
#include <base32_code.h>
/* Application-specific. */
static unsigned char to_b32[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
#define UNSIG_CHAR_PTR(x) ((unsigned char *)(x))
/* base32_encode - raw data to encoded */
VSTRING *base32_encode(VSTRING *result, const char *in, ssize_t len)
{
const unsigned char *cp;
ssize_t count;
static int pad_count[] = {0, 6, 4, 3, 1};
/*
* Encode 5 -> 8.
*/
VSTRING_RESET(result);
for (cp = UNSIG_CHAR_PTR(in), count = len; count > 0; count -= 5, cp += 5) {
VSTRING_ADDCH(result, to_b32[cp[0] >> 3]);
if (count < 2) {
VSTRING_ADDCH(result, to_b32[(cp[0] & 0x7) << 2]);
break;
}
VSTRING_ADDCH(result, to_b32[(cp[0] & 0x7) << 2 | cp[1] >> 6]);
VSTRING_ADDCH(result, to_b32[(cp[1] & 0x3f) >> 1]);
if (count < 3) {
VSTRING_ADDCH(result, to_b32[(cp[1] & 0x1) << 4]);
break;
}
VSTRING_ADDCH(result, to_b32[(cp[1] & 0x1) << 4 | cp[2] >> 4]);
if (count < 4) {
VSTRING_ADDCH(result, to_b32[(cp[2] & 0xf) << 1]);
break;
}
VSTRING_ADDCH(result, to_b32[(cp[2] & 0xf) << 1 | cp[3] >> 7]);
VSTRING_ADDCH(result, to_b32[(cp[3] & 0x7f) >> 2]);
if (count < 5) {
VSTRING_ADDCH(result, to_b32[(cp[3] & 0x3) << 3]);
break;
}
VSTRING_ADDCH(result, to_b32[(cp[3] & 0x3) << 3 | cp[4] >> 5]);
VSTRING_ADDCH(result, to_b32[cp[4] & 0x1f]);
}
if (count > 0)
vstring_strncat(result, "======", pad_count[count]);
VSTRING_TERMINATE(result);
return (result);
}
/* base32_decode - encoded data to raw */
VSTRING *base32_decode(VSTRING *result, const char *in, ssize_t len)
{
static unsigned char *un_b32 = 0;
const unsigned char *cp;
ssize_t count;
unsigned int ch0;
unsigned int ch1;
unsigned int ch2;
unsigned int ch3;
unsigned int ch4;
unsigned int ch5;
unsigned int ch6;
unsigned int ch7;
#define CHARS_PER_BYTE (UCHAR_MAX + 1)
#define INVALID 0xff
#if 1
#define ENFORCE_LENGTH(x) (x)
#define ENFORCE_PADDING(x) (x)
#define ENFORCE_NULL_BITS(x) (x)
#else
#define ENFORCE_LENGTH(x) (1)
#define ENFORCE_PADDING(x) (1)
#define ENFORCE_NULL_BITS(x) (1)
#endif
/*
* Sanity check.
*/
if (ENFORCE_LENGTH(len % 8))
return (0);
/*
* Once: initialize the decoding lookup table on the fly.
*/
if (un_b32 == 0) {
un_b32 = (unsigned char *) mymalloc(CHARS_PER_BYTE);
memset(un_b32, INVALID, CHARS_PER_BYTE);
for (cp = to_b32; cp < to_b32 + sizeof(to_b32) - 1; cp++)
un_b32[*cp] = cp - to_b32;
}
/*
* Decode 8 -> 5.
*/
VSTRING_RESET(result);
for (cp = UNSIG_CHAR_PTR(in), count = 0; count < len; count += 8) {
if ((ch0 = un_b32[*cp++]) == INVALID
|| (ch1 = un_b32[*cp++]) == INVALID)
return (0);
VSTRING_ADDCH(result, ch0 << 3 | ch1 >> 2);
if ((ch2 = *cp++) == '='
&& ENFORCE_PADDING(strcmp((char *) cp, "=====") == 0)
&& ENFORCE_NULL_BITS((ch1 & 0x3) == 0))
break;
if ((ch2 = un_b32[ch2]) == INVALID)
return (0);
if ((ch3 = un_b32[*cp++]) == INVALID)
return (0);
VSTRING_ADDCH(result, ch1 << 6 | ch2 << 1 | ch3 >> 4);
if ((ch4 = *cp++) == '='
&& ENFORCE_PADDING(strcmp((char *) cp, "===") == 0)
&& ENFORCE_NULL_BITS((ch3 & 0xf) == 0))
break;
if ((ch4 = un_b32[ch4]) == INVALID)
return (0);
VSTRING_ADDCH(result, ch3 << 4 | ch4 >> 1);
if ((ch5 = *cp++) == '='
&& ENFORCE_PADDING(strcmp((char *) cp, "==") == 0)
&& ENFORCE_NULL_BITS((ch4 & 0x1) == 0))
break;
if ((ch5 = un_b32[ch5]) == INVALID)
return (0);
if ((ch6 = un_b32[*cp++]) == INVALID)
return (0);
VSTRING_ADDCH(result, ch4 << 7 | ch5 << 2 | ch6 >> 3);
if ((ch7 = *cp++) == '='
&& ENFORCE_NULL_BITS((ch6 & 0x7) == 0))
break;
if ((ch7 = un_b32[ch7]) == INVALID)
return (0);
VSTRING_ADDCH(result, ch6 << 5 | ch7);
}
VSTRING_TERMINATE(result);
return (result);
}
#ifdef TEST
/*
* Proof-of-concept test program: convert to base 32 and back.
*/
#define STR(x) vstring_str(x)
#define LEN(x) VSTRING_LEN(x)
int main(int unused_argc, char **unused_argv)
{
VSTRING *b1 = vstring_alloc(1);
VSTRING *b2 = vstring_alloc(1);
VSTRING *test = vstring_alloc(1);
int i, j;
/*
* Test all byte values (except null) on all byte positions.
*/
for (j = 0; j < 256; j++)
for (i = 1; i < 256; i++)
VSTRING_ADDCH(test, i);
VSTRING_TERMINATE(test);
#define DECODE(b,x,l) { \
if (base32_decode((b),(x),(l)) == 0) \
msg_panic("bad base32: %s", (x)); \
}
#define VERIFY(b,t,l) { \
if (memcmp((b), (t), (l)) != 0) \
msg_panic("bad test: %s", (b)); \
}
/*
* Test all padding variants.
*/
for (i = 1; i <= 8; i++) {
base32_encode(b1, STR(test), LEN(test));
DECODE(b2, STR(b1), LEN(b1));
VERIFY(STR(b2), STR(test), LEN(test));
base32_encode(b1, STR(test), LEN(test));
base32_encode(b2, STR(b1), LEN(b1));
base32_encode(b1, STR(b2), LEN(b2));
DECODE(b2, STR(b1), LEN(b1));
DECODE(b1, STR(b2), LEN(b2));
DECODE(b2, STR(b1), LEN(b1));
VERIFY(STR(b2), STR(test), LEN(test));
base32_encode(b1, STR(test), LEN(test));
base32_encode(b2, STR(b1), LEN(b1));
base32_encode(b1, STR(b2), LEN(b2));
base32_encode(b2, STR(b1), LEN(b1));
base32_encode(b1, STR(b2), LEN(b2));
DECODE(b2, STR(b1), LEN(b1));
DECODE(b1, STR(b2), LEN(b2));
DECODE(b2, STR(b1), LEN(b1));
DECODE(b1, STR(b2), LEN(b2));
DECODE(b2, STR(b1), LEN(b1));
VERIFY(STR(b2), STR(test), LEN(test));
vstring_truncate(test, LEN(test) - 1);
}
vstring_free(test);
vstring_free(b1);
vstring_free(b2);
return (0);
}
#endif
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