package org.bouncycastle.math.ec.custom.sec; import java.math.BigInteger; import org.bouncycastle.math.ec.ECFieldElement; import org.bouncycastle.math.raw.Mod; import org.bouncycastle.math.raw.Nat192; import org.bouncycastle.util.Arrays; public class SecP192K1FieldElement extends ECFieldElement { public static final BigInteger Q = SecP192K1Curve.q; protected int[] x; public SecP192K1FieldElement(BigInteger x) { if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0) { throw new IllegalArgumentException("x value invalid for SecP192K1FieldElement"); } this.x = SecP192K1Field.fromBigInteger(x); } public SecP192K1FieldElement() { this.x = Nat192.create(); } protected SecP192K1FieldElement(int[] x) { this.x = x; } public boolean isZero() { return Nat192.isZero(x); } public boolean isOne() { return Nat192.isOne(x); } public boolean testBitZero() { return Nat192.getBit(x, 0) == 1; } public BigInteger toBigInteger() { return Nat192.toBigInteger(x); } public String getFieldName() { return "SecP192K1Field"; } public int getFieldSize() { return Q.bitLength(); } public ECFieldElement add(ECFieldElement b) { int[] z = Nat192.create(); SecP192K1Field.add(x, ((SecP192K1FieldElement)b).x, z); return new SecP192K1FieldElement(z); } public ECFieldElement addOne() { int[] z = Nat192.create(); SecP192K1Field.addOne(x, z); return new SecP192K1FieldElement(z); } public ECFieldElement subtract(ECFieldElement b) { int[] z = Nat192.create(); SecP192K1Field.subtract(x, ((SecP192K1FieldElement)b).x, z); return new SecP192K1FieldElement(z); } public ECFieldElement multiply(ECFieldElement b) { int[] z = Nat192.create(); SecP192K1Field.multiply(x, ((SecP192K1FieldElement)b).x, z); return new SecP192K1FieldElement(z); } public ECFieldElement divide(ECFieldElement b) { // return multiply(b.invert()); int[] z = Nat192.create(); Mod.invert(SecP192K1Field.P, ((SecP192K1FieldElement)b).x, z); SecP192K1Field.multiply(z, x, z); return new SecP192K1FieldElement(z); } public ECFieldElement negate() { int[] z = Nat192.create(); SecP192K1Field.negate(x, z); return new SecP192K1FieldElement(z); } public ECFieldElement square() { int[] z = Nat192.create(); SecP192K1Field.square(x, z); return new SecP192K1FieldElement(z); } public ECFieldElement invert() { // return new SecP192K1FieldElement(toBigInteger().modInverse(Q)); int[] z = Nat192.create(); Mod.invert(SecP192K1Field.P, x, z); return new SecP192K1FieldElement(z); } /** * return a sqrt root - the routine verifies that the calculation returns the right value - if * none exists it returns null. */ public ECFieldElement sqrt() { /* * Raise this element to the exponent 2^190 - 2^30 - 2^10 - 2^6 - 2^5 - 2^4 - 2^1 * * Breaking up the exponent's binary representation into "repunits", we get: * { 159 1s } { 1 0s } { 19 1s } { 1 0s } { 3 1s } { 3 0s} { 3 1s } { 1 0s } * * Therefore we need an addition chain containing 3, 19, 159 (the lengths of the repunits) * We use: 1, 2, [3], 6, 8, 16, [19], 35, 70, 140, [159] */ int[] x1 = this.x; if (Nat192.isZero(x1) || Nat192.isOne(x1)) { return this; } int[] x2 = Nat192.create(); SecP192K1Field.square(x1, x2); SecP192K1Field.multiply(x2, x1, x2); int[] x3 = Nat192.create(); SecP192K1Field.square(x2, x3); SecP192K1Field.multiply(x3, x1, x3); int[] x6 = Nat192.create(); SecP192K1Field.squareN(x3, 3, x6); SecP192K1Field.multiply(x6, x3, x6); int[] x8 = x6; SecP192K1Field.squareN(x6, 2, x8); SecP192K1Field.multiply(x8, x2, x8); int[] x16 = x2; SecP192K1Field.squareN(x8, 8, x16); SecP192K1Field.multiply(x16, x8, x16); int[] x19 = x8; SecP192K1Field.squareN(x16, 3, x19); SecP192K1Field.multiply(x19, x3, x19); int[] x35 = Nat192.create(); SecP192K1Field.squareN(x19, 16, x35); SecP192K1Field.multiply(x35, x16, x35); int[] x70 = x16; SecP192K1Field.squareN(x35, 35, x70); SecP192K1Field.multiply(x70, x35, x70); int[] x140 = x35; SecP192K1Field.squareN(x70, 70, x140); SecP192K1Field.multiply(x140, x70, x140); int[] x159 = x70; SecP192K1Field.squareN(x140, 19, x159); SecP192K1Field.multiply(x159, x19, x159); int[] t1 = x159; SecP192K1Field.squareN(t1, 20, t1); SecP192K1Field.multiply(t1, x19, t1); SecP192K1Field.squareN(t1, 4, t1); SecP192K1Field.multiply(t1, x3, t1); SecP192K1Field.squareN(t1, 6, t1); SecP192K1Field.multiply(t1, x3, t1); SecP192K1Field.square(t1, t1); int[] t2 = x3; SecP192K1Field.square(t1, t2); return Nat192.eq(x1, t2) ? new SecP192K1FieldElement(t1) : null; } public boolean equals(Object other) { if (other == this) { return true; } if (!(other instanceof SecP192K1FieldElement)) { return false; } SecP192K1FieldElement o = (SecP192K1FieldElement)other; return Nat192.eq(x, o.x); } public int hashCode() { return Q.hashCode() ^ Arrays.hashCode(x, 0, 6); } }