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
|
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <compressor.h>
#include <pubkey.h>
#include <script/script.h>
/*
* These check for scripts for which a special case with a shorter encoding is defined.
* They are implemented separately from the CScript test, as these test for exact byte
* sequence correspondences, and are more strict. For example, IsToPubKey also verifies
* whether the public key is valid (as invalid ones cannot be represented in compressed
* form).
*/
static bool IsToKeyID(const CScript& script, CKeyID &hash)
{
if (script.size() == 25 && script[0] == OP_DUP && script[1] == OP_HASH160
&& script[2] == 20 && script[23] == OP_EQUALVERIFY
&& script[24] == OP_CHECKSIG) {
memcpy(&hash, &script[3], 20);
return true;
}
return false;
}
static bool IsToScriptID(const CScript& script, CScriptID &hash)
{
if (script.size() == 23 && script[0] == OP_HASH160 && script[1] == 20
&& script[22] == OP_EQUAL) {
memcpy(&hash, &script[2], 20);
return true;
}
return false;
}
static bool IsToPubKey(const CScript& script, CPubKey &pubkey)
{
if (script.size() == 35 && script[0] == 33 && script[34] == OP_CHECKSIG
&& (script[1] == 0x02 || script[1] == 0x03)) {
pubkey.Set(&script[1], &script[34]);
return true;
}
if (script.size() == 67 && script[0] == 65 && script[66] == OP_CHECKSIG
&& script[1] == 0x04) {
pubkey.Set(&script[1], &script[66]);
return pubkey.IsFullyValid(); // if not fully valid, a case that would not be compressible
}
return false;
}
bool CompressScript(const CScript& script, CompressedScript& out)
{
CKeyID keyID;
if (IsToKeyID(script, keyID)) {
out.resize(21);
out[0] = 0x00;
memcpy(&out[1], &keyID, 20);
return true;
}
CScriptID scriptID;
if (IsToScriptID(script, scriptID)) {
out.resize(21);
out[0] = 0x01;
memcpy(&out[1], &scriptID, 20);
return true;
}
CPubKey pubkey;
if (IsToPubKey(script, pubkey)) {
out.resize(33);
memcpy(&out[1], &pubkey[1], 32);
if (pubkey[0] == 0x02 || pubkey[0] == 0x03) {
out[0] = pubkey[0];
return true;
} else if (pubkey[0] == 0x04) {
out[0] = 0x04 | (pubkey[64] & 0x01);
return true;
}
}
return false;
}
unsigned int GetSpecialScriptSize(unsigned int nSize)
{
if (nSize == 0 || nSize == 1)
return 20;
if (nSize == 2 || nSize == 3 || nSize == 4 || nSize == 5)
return 32;
return 0;
}
bool DecompressScript(CScript& script, unsigned int nSize, const CompressedScript& in)
{
switch(nSize) {
case 0x00:
script.resize(25);
script[0] = OP_DUP;
script[1] = OP_HASH160;
script[2] = 20;
memcpy(&script[3], in.data(), 20);
script[23] = OP_EQUALVERIFY;
script[24] = OP_CHECKSIG;
return true;
case 0x01:
script.resize(23);
script[0] = OP_HASH160;
script[1] = 20;
memcpy(&script[2], in.data(), 20);
script[22] = OP_EQUAL;
return true;
case 0x02:
case 0x03:
script.resize(35);
script[0] = 33;
script[1] = nSize;
memcpy(&script[2], in.data(), 32);
script[34] = OP_CHECKSIG;
return true;
case 0x04:
case 0x05:
unsigned char vch[33] = {};
vch[0] = nSize - 2;
memcpy(&vch[1], in.data(), 32);
CPubKey pubkey{vch};
if (!pubkey.Decompress())
return false;
assert(pubkey.size() == 65);
script.resize(67);
script[0] = 65;
memcpy(&script[1], pubkey.begin(), 65);
script[66] = OP_CHECKSIG;
return true;
}
return false;
}
// Amount compression:
// * If the amount is 0, output 0
// * first, divide the amount (in base units) by the largest power of 10 possible; call the exponent e (e is max 9)
// * if e<9, the last digit of the resulting number cannot be 0; store it as d, and drop it (divide by 10)
// * call the result n
// * output 1 + 10*(9*n + d - 1) + e
// * if e==9, we only know the resulting number is not zero, so output 1 + 10*(n - 1) + 9
// (this is decodable, as d is in [1-9] and e is in [0-9])
uint64_t CompressAmount(uint64_t n)
{
if (n == 0)
return 0;
int e = 0;
while (((n % 10) == 0) && e < 9) {
n /= 10;
e++;
}
if (e < 9) {
int d = (n % 10);
assert(d >= 1 && d <= 9);
n /= 10;
return 1 + (n*9 + d - 1)*10 + e;
} else {
return 1 + (n - 1)*10 + 9;
}
}
uint64_t DecompressAmount(uint64_t x)
{
// x = 0 OR x = 1+10*(9*n + d - 1) + e OR x = 1+10*(n - 1) + 9
if (x == 0)
return 0;
x--;
// x = 10*(9*n + d - 1) + e
int e = x % 10;
x /= 10;
uint64_t n = 0;
if (e < 9) {
// x = 9*n + d - 1
int d = (x % 9) + 1;
x /= 9;
// x = n
n = x*10 + d;
} else {
n = x+1;
}
while (e) {
n *= 10;
e--;
}
return n;
}
|
