1package org.bouncycastle.math.ec.custom.sec;
2
3import org.bouncycastle.math.ec.ECCurve;
4import org.bouncycastle.math.ec.ECFieldElement;
5import org.bouncycastle.math.ec.ECPoint;
6import org.bouncycastle.math.raw.Nat;
7import org.bouncycastle.math.raw.Nat192;
8
9public class SecP192R1Point extends ECPoint.AbstractFp
10{
11    /**
12     * Create a point which encodes with point compression.
13     *
14     * @param curve
15     *            the curve to use
16     * @param x
17     *            affine x co-ordinate
18     * @param y
19     *            affine y co-ordinate
20     *
21     * @deprecated Use ECCurve.createPoint to construct points
22     */
23    public SecP192R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y)
24    {
25        this(curve, x, y, false);
26    }
27
28    /**
29     * Create a point that encodes with or without point compresion.
30     *
31     * @param curve
32     *            the curve to use
33     * @param x
34     *            affine x co-ordinate
35     * @param y
36     *            affine y co-ordinate
37     * @param withCompression
38     *            if true encode with point compression
39     *
40     * @deprecated per-point compression property will be removed, refer
41     *             {@link #getEncoded(boolean)}
42     */
43    public SecP192R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, boolean withCompression)
44    {
45        super(curve, x, y);
46
47        if ((x == null) != (y == null))
48        {
49            throw new IllegalArgumentException("Exactly one of the field elements is null");
50        }
51
52        this.withCompression = withCompression;
53    }
54
55    SecP192R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs, boolean withCompression)
56    {
57        super(curve, x, y, zs);
58
59        this.withCompression = withCompression;
60    }
61
62    protected ECPoint detach()
63    {
64        return new SecP192R1Point(null, getAffineXCoord(), getAffineYCoord());
65    }
66
67    // B.3 pg 62
68    public ECPoint add(ECPoint b)
69    {
70        if (this.isInfinity())
71        {
72            return b;
73        }
74        if (b.isInfinity())
75        {
76            return this;
77        }
78        if (this == b)
79        {
80            return twice();
81        }
82
83        ECCurve curve = this.getCurve();
84
85        SecP192R1FieldElement X1 = (SecP192R1FieldElement)this.x, Y1 = (SecP192R1FieldElement)this.y;
86        SecP192R1FieldElement X2 = (SecP192R1FieldElement)b.getXCoord(), Y2 = (SecP192R1FieldElement)b.getYCoord();
87
88        SecP192R1FieldElement Z1 = (SecP192R1FieldElement)this.zs[0];
89        SecP192R1FieldElement Z2 = (SecP192R1FieldElement)b.getZCoord(0);
90
91        int c;
92        int[] tt1 = Nat192.createExt();
93        int[] t2 = Nat192.create();
94        int[] t3 = Nat192.create();
95        int[] t4 = Nat192.create();
96
97        boolean Z1IsOne = Z1.isOne();
98        int[] U2, S2;
99        if (Z1IsOne)
100        {
101            U2 = X2.x;
102            S2 = Y2.x;
103        }
104        else
105        {
106            S2 = t3;
107            SecP192R1Field.square(Z1.x, S2);
108
109            U2 = t2;
110            SecP192R1Field.multiply(S2, X2.x, U2);
111
112            SecP192R1Field.multiply(S2, Z1.x, S2);
113            SecP192R1Field.multiply(S2, Y2.x, S2);
114        }
115
116        boolean Z2IsOne = Z2.isOne();
117        int[] U1, S1;
118        if (Z2IsOne)
119        {
120            U1 = X1.x;
121            S1 = Y1.x;
122        }
123        else
124        {
125            S1 = t4;
126            SecP192R1Field.square(Z2.x, S1);
127
128            U1 = tt1;
129            SecP192R1Field.multiply(S1, X1.x, U1);
130
131            SecP192R1Field.multiply(S1, Z2.x, S1);
132            SecP192R1Field.multiply(S1, Y1.x, S1);
133        }
134
135        int[] H = Nat192.create();
136        SecP192R1Field.subtract(U1, U2, H);
137
138        int[] R = t2;
139        SecP192R1Field.subtract(S1, S2, R);
140
141        // Check if b == this or b == -this
142        if (Nat192.isZero(H))
143        {
144            if (Nat192.isZero(R))
145            {
146                // this == b, i.e. this must be doubled
147                return this.twice();
148            }
149
150            // this == -b, i.e. the result is the point at infinity
151            return curve.getInfinity();
152        }
153
154        int[] HSquared = t3;
155        SecP192R1Field.square(H, HSquared);
156
157        int[] G = Nat192.create();
158        SecP192R1Field.multiply(HSquared, H, G);
159
160        int[] V = t3;
161        SecP192R1Field.multiply(HSquared, U1, V);
162
163        SecP192R1Field.negate(G, G);
164        Nat192.mul(S1, G, tt1);
165
166        c = Nat192.addBothTo(V, V, G);
167        SecP192R1Field.reduce32(c, G);
168
169        SecP192R1FieldElement X3 = new SecP192R1FieldElement(t4);
170        SecP192R1Field.square(R, X3.x);
171        SecP192R1Field.subtract(X3.x, G, X3.x);
172
173        SecP192R1FieldElement Y3 = new SecP192R1FieldElement(G);
174        SecP192R1Field.subtract(V, X3.x, Y3.x);
175        SecP192R1Field.multiplyAddToExt(Y3.x, R, tt1);
176        SecP192R1Field.reduce(tt1, Y3.x);
177
178        SecP192R1FieldElement Z3 = new SecP192R1FieldElement(H);
179        if (!Z1IsOne)
180        {
181            SecP192R1Field.multiply(Z3.x, Z1.x, Z3.x);
182        }
183        if (!Z2IsOne)
184        {
185            SecP192R1Field.multiply(Z3.x, Z2.x, Z3.x);
186        }
187
188        ECFieldElement[] zs = new ECFieldElement[]{ Z3 };
189
190        return new SecP192R1Point(curve, X3, Y3, zs, this.withCompression);
191    }
192
193    // B.3 pg 62
194    public ECPoint twice()
195    {
196        if (this.isInfinity())
197        {
198            return this;
199        }
200
201        ECCurve curve = this.getCurve();
202
203        SecP192R1FieldElement Y1 = (SecP192R1FieldElement)this.y;
204        if (Y1.isZero())
205        {
206            return curve.getInfinity();
207        }
208
209        SecP192R1FieldElement X1 = (SecP192R1FieldElement)this.x, Z1 = (SecP192R1FieldElement)this.zs[0];
210
211        int c;
212        int[] t1 = Nat192.create();
213        int[] t2 = Nat192.create();
214
215        int[] Y1Squared = Nat192.create();
216        SecP192R1Field.square(Y1.x, Y1Squared);
217
218        int[] T = Nat192.create();
219        SecP192R1Field.square(Y1Squared, T);
220
221        boolean Z1IsOne = Z1.isOne();
222
223        int[] Z1Squared = Z1.x;
224        if (!Z1IsOne)
225        {
226            Z1Squared = t2;
227            SecP192R1Field.square(Z1.x, Z1Squared);
228        }
229
230        SecP192R1Field.subtract(X1.x, Z1Squared, t1);
231
232        int[] M = t2;
233        SecP192R1Field.add(X1.x, Z1Squared, M);
234        SecP192R1Field.multiply(M, t1, M);
235        c = Nat192.addBothTo(M, M, M);
236        SecP192R1Field.reduce32(c, M);
237
238        int[] S = Y1Squared;
239        SecP192R1Field.multiply(Y1Squared, X1.x, S);
240        c = Nat.shiftUpBits(6, S, 2, 0);
241        SecP192R1Field.reduce32(c, S);
242
243        c = Nat.shiftUpBits(6, T, 3, 0, t1);
244        SecP192R1Field.reduce32(c, t1);
245
246        SecP192R1FieldElement X3 = new SecP192R1FieldElement(T);
247        SecP192R1Field.square(M, X3.x);
248        SecP192R1Field.subtract(X3.x, S, X3.x);
249        SecP192R1Field.subtract(X3.x, S, X3.x);
250
251        SecP192R1FieldElement Y3 = new SecP192R1FieldElement(S);
252        SecP192R1Field.subtract(S, X3.x, Y3.x);
253        SecP192R1Field.multiply(Y3.x, M, Y3.x);
254        SecP192R1Field.subtract(Y3.x, t1, Y3.x);
255
256        SecP192R1FieldElement Z3 = new SecP192R1FieldElement(M);
257        SecP192R1Field.twice(Y1.x, Z3.x);
258        if (!Z1IsOne)
259        {
260            SecP192R1Field.multiply(Z3.x, Z1.x, Z3.x);
261        }
262
263        return new SecP192R1Point(curve, X3, Y3, new ECFieldElement[]{ Z3 }, this.withCompression);
264    }
265
266    public ECPoint twicePlus(ECPoint b)
267    {
268        if (this == b)
269        {
270            return threeTimes();
271        }
272        if (this.isInfinity())
273        {
274            return b;
275        }
276        if (b.isInfinity())
277        {
278            return twice();
279        }
280
281        ECFieldElement Y1 = this.y;
282        if (Y1.isZero())
283        {
284            return b;
285        }
286
287        return twice().add(b);
288    }
289
290    public ECPoint threeTimes()
291    {
292        if (this.isInfinity() || this.y.isZero())
293        {
294            return this;
295        }
296
297        // NOTE: Be careful about recursions between twicePlus and threeTimes
298        return twice().add(this);
299    }
300
301    public ECPoint negate()
302    {
303        if (this.isInfinity())
304        {
305            return this;
306        }
307
308        return new SecP192R1Point(curve, this.x, this.y.negate(), this.zs, this.withCompression);
309    }
310}
311