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/*
* Copyright 2012-2014 Luke Dashjr
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the standard MIT license. See COPYING for more details.
*
* https://github.com/luke-jr/libbase58
*/
#include <stdio.h>
#include <stdint.h>
#include <string.h>
static const int8_t b58digits_map[] = {
-1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1,
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8,-1,-1,-1,-1,-1,-1,
-1, 9,10,11,12,13,14,15, 16,-1,17,18,19,20,21,-1,
22,23,24,25,26,27,28,29, 30,31,32,-1,-1,-1,-1,-1,
-1,33,34,35,36,37,38,39, 40,41,42,43,-1,44,45,46,
47,48,49,50,51,52,53,54, 55,56,57,-1,-1,-1,-1,-1,
};
int b58tobin(void *bin, size_t *binszp, const char *b58, size_t b58sz)
{
size_t binsz = *binszp;
const unsigned char *b58u = (void*)b58;
unsigned char *binu = bin;
size_t outisz = (binsz + 3) / 4;
uint32_t outi[outisz];
uint64_t t;
uint32_t c;
size_t i, j;
uint8_t bytesleft = binsz % 4;
uint32_t zeromask = bytesleft ? (0xffffffff << (bytesleft * 8)) : 0;
unsigned zerocount = 0;
if (!b58sz)
b58sz = strlen(b58);
memset(outi, 0, outisz * sizeof(*outi));
// Leading zeros, just count
for (i = 0; i < b58sz && b58u[i] == '1'; ++i)
++zerocount;
for ( ; i < b58sz; ++i)
{
if (b58u[i] & 0x80)
// High-bit set on invalid digit
return 0;
if (b58digits_map[b58u[i]] == -1)
// Invalid base58 digit
return 0;
c = (unsigned)b58digits_map[b58u[i]];
for (j = outisz; j--; )
{
t = ((uint64_t)outi[j]) * 58 + c;
c = (t & 0x3f00000000) >> 32;
outi[j] = t & 0xffffffff;
}
if (c)
// Output number too big (carry to the next int32)
return 0;
if (outi[0] & zeromask)
// Output number too big (last int32 filled too far)
return 0;
}
j = 0;
switch (bytesleft) {
case 3:
*(binu++) = (outi[0] & 0xff0000) >> 16;
case 2:
*(binu++) = (outi[0] & 0xff00) >> 8;
case 1:
*(binu++) = (outi[0] & 0xff);
++j;
default:
break;
}
for (; j < outisz; ++j)
{
*(binu++) = (outi[j] >> 0x18) & 0xff;
*(binu++) = (outi[j] >> 0x10) & 0xff;
*(binu++) = (outi[j] >> 8) & 0xff;
*(binu++) = (outi[j] >> 0) & 0xff;
}
// Count canonical base58 byte count
binu = bin;
for (i = 0; i < binsz; ++i)
{
if (binu[i])
break;
--*binszp;
}
*binszp += zerocount;
return 1;
}
static const char b58digits_ordered[] = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
int b58enc(char *b58, size_t *b58sz, const void *data, size_t binsz)
{
const uint8_t *bin = data;
int carry;
ssize_t i, j, high, zcount = 0;
size_t size;
while (zcount < binsz && !bin[zcount])
++zcount;
size = (binsz - zcount) * 138 / 100 + 1;
uint8_t buf[size];
memset(buf, 0, size);
for (i = zcount, high = size - 1; i < binsz; ++i, high = j)
{
for (carry = bin[i], j = size - 1; (j > high) || carry; --j)
{
carry += 256 * buf[j];
buf[j] = carry % 58;
carry /= 58;
}
}
for (j = 0; j < size && !buf[j]; ++j);
if (*b58sz <= zcount + size - j)
{
*b58sz = zcount + size - j + 1;
return 0;
}
if (zcount)
memset(b58, '1', zcount);
for (i = zcount; j < size; ++i, ++j)
b58[i] = b58digits_ordered[buf[j]];
b58[i] = '\0';
*b58sz = i + 1;
return 1;
}
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