base58.c

#include <stdio.h>
#include <stdlib.h>
#include "common.h"
#include "base58.h"
#include "sha2.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,
};

bool b58tobin(void *bin, size_t *binszp, const char *b58)
{
	size_t binsz = *binszp;
	const unsigned char *b58u = (const unsigned char *)b58;
	unsigned char *binu = (unsigned char *)bin;
	size_t outisz = (binsz + 3) / 4;
	uint32_t* outi = (uint32_t*)malloc(sizeof(uint32_t)*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;
	size_t b58sz;

	b58sz = strlen(b58);

	memset(outi, 0, outisz * sizeof(*outi));

	// Leading zeros, just count
	for (i = 0; i < b58sz && !b58digits_map[b58u[i]]; ++i)
		++zerocount;

	for (; i < b58sz; ++i)
	{
		if (b58u[i] & 0x80)
			// High-bit set on invalid digit
			return false;
		if (b58digits_map[b58u[i]] == -1)
			// Invalid base58 digit
			return false;
		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 false;
		if (outi[0] & zeromask)
			// Output number too big (last int32 filled too far)
			return false;
	}

	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 = (unsigned char*)bin;
	for (i = 0; i < binsz; ++i)
	{
		if (binu[i])
			break;
		--*binszp;
	}
	*binszp += zerocount;
	free(outi);
	return true;
}

int b58check(const void *bin, size_t binsz, const char *base58str)
{
	unsigned char buf[32];
	const uint8_t *binc = (const uint8_t *)bin;
	unsigned i;
	if (binsz < 4)
		return -4;
	sha256_Raw((const uint8_t *)bin, binsz - 4, buf);
	sha256_Raw(buf, 32, buf);
	if (memcmp(&binc[binsz - 4], buf, 4))
		return -1;

	// Check number of zeros is correct AFTER verifying checksum (to avoid possibility of accessing base58str beyond the end)
	for (i = 0; binc[i] == '\0' && base58str[i] == '1'; ++i)
	{
	}  // Just finding the end of zeros, nothing to do in loop
	if (binc[i] == '\0' || base58str[i] == '1')
		return -3;

	return binc[0];
}

static const char b58digits_ordered[] = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";

bool b58enc(char *b58, size_t *b58sz, const void *data, size_t binsz)
{
	const uint8_t *bin = (const uint8_t *)data;
	int carry;
	size_t i, j, high, zcount = 0;
	size_t size;

	while (zcount < (size_t)binsz && !bin[zcount])
		++zcount;

	size = (binsz - zcount) * 138 / 100 + 1;
	uint8_t* buf = (uint8_t*)malloc(size * sizeof(uint8_t));
	memset(buf, 0, size);

	for (i = zcount, high = size - 1; i < (size_t)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_t)size && !buf[j]; ++j);

	if (*b58sz <= zcount + size - j)
	{
		*b58sz = zcount + size - j + 1;
		return false;
	}

	if (zcount)
		memset(b58, '1', zcount);
	for (i = zcount; j < (size_t)size; ++i, ++j)
		b58[i] = b58digits_ordered[buf[j]];
	b58[i] = '\0';
	*b58sz = i + 1;

	free(buf);
	return true;
}

#include <stdio.h>

int base58_encode_check(const uint8_t *data, int datalen, char *str, int strsize)
{
	if (datalen > 128) {
		return 0;
	}
	uint8_t* buf = (uint8_t*)malloc(sizeof(uint8_t)*(datalen + 32));
	uint8_t *hash = buf + datalen;
	memcpy(buf, data, datalen);
	sha256_Raw(data, datalen, hash);
	sha256_Raw(hash, 32, hash);
	size_t res = strsize;
	if (b58enc(str, &res, buf, datalen + 4) != true) {
		return 0;
	}
	free(buf);
	return res;
}

int base58_decode_check(const char *str, uint8_t *data, int datalen)
{
	if (datalen > 128) {
		return 0;
	}
	uint8_t* d = (uint8_t*)malloc(sizeof(uint8_t)*(datalen + 4));
	size_t res = datalen + 4;
	if (b58tobin(d, &res, str) != true) {
		return 0;
	}
	if (res != (size_t)datalen + 4) {
		return 0;
	}
	if (b58check(d, res, str) < 0) {
		return 0;
	}
	memcpy(data, d, datalen);
	free(d);
	return datalen;
}