File: base58.c

package info (click to toggle)
libbase58 0.1.4-1
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 180 kB
  • ctags: 19
  • sloc: ansic: 288; makefile: 58; sh: 32
file content (201 lines) | stat: -rw-r--r-- 4,662 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
/*
 * 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.
 */

#ifndef WIN32
#include <arpa/inet.h>
#else
#include <winsock2.h>
#endif

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <sys/types.h>

#include "libbase58.h"

bool (*b58_sha256_impl)(void *, const void *, size_t) = NULL;

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

static
bool my_dblsha256(void *hash, const void *data, size_t datasz)
{
	uint8_t buf[0x20];
	return b58_sha256_impl(buf, data, datasz) && b58_sha256_impl(hash, buf, sizeof(buf));
}

int b58check(const void *bin, size_t binsz, const char *base58str, size_t b58sz)
{
	unsigned char buf[32];
	const uint8_t *binc = bin;
	unsigned i;
	if (binsz < 4)
		return -4;
	if (!my_dblsha256(buf, bin, binsz - 4))
		return -2;
	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 = 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 false;
	}
	
	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 true;
}

bool b58check_enc(char *b58c, size_t *b58c_sz, uint8_t ver, const void *data, size_t datasz)
{
	uint8_t buf[1 + datasz + 0x20];
	uint8_t *hash = &buf[1 + datasz];
	
	buf[0] = ver;
	memcpy(&buf[1], data, datasz);
	if (!my_dblsha256(hash, buf, datasz + 1))
	{
		*b58c_sz = 0;
		return false;
	}
	
	return b58enc(b58c, b58c_sz, buf, 1 + datasz + 4);
}