1package org.bouncycastle.math.ec.custom.sec;
2
3import java.math.BigInteger;
4
5import org.bouncycastle.math.ec.ECFieldElement;
6import org.bouncycastle.math.raw.Mod;
7import org.bouncycastle.math.raw.Nat;
8import org.bouncycastle.util.Arrays;
9
10public class SecP384R1FieldElement extends ECFieldElement
11{
12    public static final BigInteger Q = SecP384R1Curve.q;
13
14    protected int[] x;
15
16    public SecP384R1FieldElement(BigInteger x)
17    {
18        if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0)
19        {
20            throw new IllegalArgumentException("x value invalid for SecP384R1FieldElement");
21        }
22
23        this.x = SecP384R1Field.fromBigInteger(x);
24    }
25
26    public SecP384R1FieldElement()
27    {
28        this.x = Nat.create(12);
29    }
30
31    protected SecP384R1FieldElement(int[] x)
32    {
33        this.x = x;
34    }
35
36    public boolean isZero()
37    {
38        return Nat.isZero(12, x);
39    }
40
41    public boolean isOne()
42    {
43        return Nat.isOne(12, x);
44    }
45
46    public boolean testBitZero()
47    {
48        return Nat.getBit(x, 0) == 1;
49    }
50
51    public BigInteger toBigInteger()
52    {
53        return Nat.toBigInteger(12, x);
54    }
55
56    public String getFieldName()
57    {
58        return "SecP384R1Field";
59    }
60
61    public int getFieldSize()
62    {
63        return Q.bitLength();
64    }
65
66    public ECFieldElement add(ECFieldElement b)
67    {
68        int[] z = Nat.create(12);
69        SecP384R1Field.add(x, ((SecP384R1FieldElement)b).x, z);
70        return new SecP384R1FieldElement(z);
71    }
72
73    public ECFieldElement addOne()
74    {
75        int[] z = Nat.create(12);
76        SecP384R1Field.addOne(x, z);
77        return new SecP384R1FieldElement(z);
78    }
79
80    public ECFieldElement subtract(ECFieldElement b)
81    {
82        int[] z = Nat.create(12);
83        SecP384R1Field.subtract(x, ((SecP384R1FieldElement)b).x, z);
84        return new SecP384R1FieldElement(z);
85    }
86
87    public ECFieldElement multiply(ECFieldElement b)
88    {
89        int[] z = Nat.create(12);
90        SecP384R1Field.multiply(x, ((SecP384R1FieldElement)b).x, z);
91        return new SecP384R1FieldElement(z);
92    }
93
94    public ECFieldElement divide(ECFieldElement b)
95    {
96//        return multiply(b.invert());
97        int[] z = Nat.create(12);
98        Mod.invert(SecP384R1Field.P, ((SecP384R1FieldElement)b).x, z);
99        SecP384R1Field.multiply(z, x, z);
100        return new SecP384R1FieldElement(z);
101    }
102
103    public ECFieldElement negate()
104    {
105        int[] z = Nat.create(12);
106        SecP384R1Field.negate(x, z);
107        return new SecP384R1FieldElement(z);
108    }
109
110    public ECFieldElement square()
111    {
112        int[] z = Nat.create(12);
113        SecP384R1Field.square(x, z);
114        return new SecP384R1FieldElement(z);
115    }
116
117    public ECFieldElement invert()
118    {
119//        return new SecP384R1FieldElement(toBigInteger().modInverse(Q));
120        int[] z = Nat.create(12);
121        Mod.invert(SecP384R1Field.P, x, z);
122        return new SecP384R1FieldElement(z);
123    }
124
125    /**
126     * return a sqrt root - the routine verifies that the calculation returns the right value - if
127     * none exists it returns null.
128     */
129    public ECFieldElement sqrt()
130    {
131        // Raise this element to the exponent 2^382 - 2^126 - 2^94 + 2^30
132
133        int[] x1 = this.x;
134        if (Nat.isZero(12, x1) || Nat.isOne(12, x1))
135        {
136            return this;
137        }
138
139        int[] t1 = Nat.create(12);
140        int[] t2 = Nat.create(12);
141        int[] t3 = Nat.create(12);
142        int[] t4 = Nat.create(12);
143
144        SecP384R1Field.square(x1, t1);
145        SecP384R1Field.multiply(t1, x1, t1);
146
147        SecP384R1Field.squareN(t1, 2, t2);
148        SecP384R1Field.multiply(t2, t1, t2);
149
150        SecP384R1Field.square(t2, t2);
151        SecP384R1Field.multiply(t2, x1, t2);
152
153        SecP384R1Field.squareN(t2, 5, t3);
154        SecP384R1Field.multiply(t3, t2, t3);
155
156        SecP384R1Field.squareN(t3, 5, t4);
157        SecP384R1Field.multiply(t4, t2, t4);
158
159        SecP384R1Field.squareN(t4, 15, t2);
160        SecP384R1Field.multiply(t2, t4, t2);
161
162        SecP384R1Field.squareN(t2, 2, t3);
163        SecP384R1Field.multiply(t1, t3, t1);
164
165        SecP384R1Field.squareN(t3, 28, t3);
166        SecP384R1Field.multiply(t2, t3, t2);
167
168        SecP384R1Field.squareN(t2, 60, t3);
169        SecP384R1Field.multiply(t3, t2, t3);
170
171        int[] r = t2;
172
173        SecP384R1Field.squareN(t3, 120, r);
174        SecP384R1Field.multiply(r, t3, r);
175
176        SecP384R1Field.squareN(r, 15, r);
177        SecP384R1Field.multiply(r, t4, r);
178
179        SecP384R1Field.squareN(r, 33, r);
180        SecP384R1Field.multiply(r, t1, r);
181
182        SecP384R1Field.squareN(r, 64, r);
183        SecP384R1Field.multiply(r, x1, r);
184
185        SecP384R1Field.squareN(r, 30, t1);
186        SecP384R1Field.square(t1, t2);
187
188        return Nat.eq(12, x1, t2) ? new SecP384R1FieldElement(t1) : null;
189    }
190
191    public boolean equals(Object other)
192    {
193        if (other == this)
194        {
195            return true;
196        }
197
198        if (!(other instanceof SecP384R1FieldElement))
199        {
200            return false;
201        }
202
203        SecP384R1FieldElement o = (SecP384R1FieldElement)other;
204        return Nat.eq(12, x, o.x);
205    }
206
207    public int hashCode()
208    {
209        return Q.hashCode() ^ Arrays.hashCode(x, 0, 12);
210    }
211}
212