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
|
/**
* EdDSA-Java by str4d
*
* To the extent possible under law, the person who associated CC0 with
* EdDSA-Java has waived all copyright and related or neighboring rights
* to EdDSA-Java.
*
* You should have received a copy of the CC0 legalcode along with this
* work. If not, see <https://creativecommons.org/publicdomain/zero/1.0/>.
*
*/
package net.i2p.crypto.eddsa.math.bigint;
import java.io.Serializable;
import java.math.BigInteger;
import net.i2p.crypto.eddsa.math.Field;
import net.i2p.crypto.eddsa.math.FieldElement;
/**
* A particular element of the field \Z/(2^255-19).
* @author str4d
*
*/
public class BigIntegerFieldElement extends FieldElement implements Serializable {
private static final long serialVersionUID = 4890398908392808L;
/**
* Variable is package private for encoding.
*/
final BigInteger bi;
public BigIntegerFieldElement(Field f, BigInteger bi) {
super(f);
this.bi = bi;
}
public boolean isNonZero() {
return !bi.equals(BigInteger.ZERO);
}
public FieldElement add(FieldElement val) {
return new BigIntegerFieldElement(f, bi.add(((BigIntegerFieldElement)val).bi)).mod(f.getQ());
}
@Override
public FieldElement addOne() {
return new BigIntegerFieldElement(f, bi.add(BigInteger.ONE)).mod(f.getQ());
}
public FieldElement subtract(FieldElement val) {
return new BigIntegerFieldElement(f, bi.subtract(((BigIntegerFieldElement)val).bi)).mod(f.getQ());
}
@Override
public FieldElement subtractOne() {
return new BigIntegerFieldElement(f, bi.subtract(BigInteger.ONE)).mod(f.getQ());
}
public FieldElement negate() {
return f.getQ().subtract(this);
}
@Override
public FieldElement divide(FieldElement val) {
return divide(((BigIntegerFieldElement)val).bi);
}
public FieldElement divide(BigInteger val) {
return new BigIntegerFieldElement(f, bi.divide(val)).mod(f.getQ());
}
public FieldElement multiply(FieldElement val) {
return new BigIntegerFieldElement(f, bi.multiply(((BigIntegerFieldElement)val).bi)).mod(f.getQ());
}
public FieldElement square() {
return multiply(this);
}
public FieldElement squareAndDouble() {
FieldElement sq = square();
return sq.add(sq);
}
public FieldElement invert() {
// Euler's theorem
//return modPow(f.getQm2(), f.getQ());
return new BigIntegerFieldElement(f, bi.modInverse(((BigIntegerFieldElement)f.getQ()).bi));
}
public FieldElement mod(FieldElement m) {
return new BigIntegerFieldElement(f, bi.mod(((BigIntegerFieldElement)m).bi));
}
public FieldElement modPow(FieldElement e, FieldElement m) {
return new BigIntegerFieldElement(f, bi.modPow(((BigIntegerFieldElement)e).bi, ((BigIntegerFieldElement)m).bi));
}
public FieldElement pow(FieldElement e){
return modPow(e, f.getQ());
}
public FieldElement pow22523(){
return pow(f.getQm5d8());
}
@Override
public FieldElement cmov(FieldElement val, int b) {
// Not constant-time, but it doesn't really matter because none of the underlying BigInteger operations
// are either, so there's not much point in trying hard here ...
return b == 0 ? this : val;
}
@Override
public int hashCode() {
return bi.hashCode();
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof BigIntegerFieldElement))
return false;
BigIntegerFieldElement fe = (BigIntegerFieldElement) obj;
return bi.equals(fe.bi);
}
@Override
public String toString() {
return "[BigIntegerFieldElement val="+bi+"]";
}
}
|
