| /* GENERATED SOURCE. DO NOT MODIFY. */ |
| package com.android.org.bouncycastle.math.ec.custom.sec; |
| |
| import java.math.BigInteger; |
| |
| import com.android.org.bouncycastle.math.ec.ECFieldElement; |
| import com.android.org.bouncycastle.math.raw.Mod; |
| import com.android.org.bouncycastle.math.raw.Nat256; |
| import com.android.org.bouncycastle.util.Arrays; |
| |
| /** |
| * @hide This class is not part of the Android public SDK API |
| */ |
| public class SecP256K1FieldElement extends ECFieldElement.AbstractFp |
| { |
| public static final BigInteger Q = SecP256K1Curve.q; |
| |
| protected int[] x; |
| |
| public SecP256K1FieldElement(BigInteger x) |
| { |
| if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0) |
| { |
| throw new IllegalArgumentException("x value invalid for SecP256K1FieldElement"); |
| } |
| |
| this.x = SecP256K1Field.fromBigInteger(x); |
| } |
| |
| public SecP256K1FieldElement() |
| { |
| this.x = Nat256.create(); |
| } |
| |
| protected SecP256K1FieldElement(int[] x) |
| { |
| this.x = x; |
| } |
| |
| public boolean isZero() |
| { |
| return Nat256.isZero(x); |
| } |
| |
| public boolean isOne() |
| { |
| return Nat256.isOne(x); |
| } |
| |
| public boolean testBitZero() |
| { |
| return Nat256.getBit(x, 0) == 1; |
| } |
| |
| public BigInteger toBigInteger() |
| { |
| return Nat256.toBigInteger(x); |
| } |
| |
| public String getFieldName() |
| { |
| return "SecP256K1Field"; |
| } |
| |
| public int getFieldSize() |
| { |
| return Q.bitLength(); |
| } |
| |
| public ECFieldElement add(ECFieldElement b) |
| { |
| int[] z = Nat256.create(); |
| SecP256K1Field.add(x, ((SecP256K1FieldElement)b).x, z); |
| return new SecP256K1FieldElement(z); |
| } |
| |
| public ECFieldElement addOne() |
| { |
| int[] z = Nat256.create(); |
| SecP256K1Field.addOne(x, z); |
| return new SecP256K1FieldElement(z); |
| } |
| |
| public ECFieldElement subtract(ECFieldElement b) |
| { |
| int[] z = Nat256.create(); |
| SecP256K1Field.subtract(x, ((SecP256K1FieldElement)b).x, z); |
| return new SecP256K1FieldElement(z); |
| } |
| |
| public ECFieldElement multiply(ECFieldElement b) |
| { |
| int[] z = Nat256.create(); |
| SecP256K1Field.multiply(x, ((SecP256K1FieldElement)b).x, z); |
| return new SecP256K1FieldElement(z); |
| } |
| |
| public ECFieldElement divide(ECFieldElement b) |
| { |
| // return multiply(b.invert()); |
| int[] z = Nat256.create(); |
| Mod.invert(SecP256K1Field.P, ((SecP256K1FieldElement)b).x, z); |
| SecP256K1Field.multiply(z, x, z); |
| return new SecP256K1FieldElement(z); |
| } |
| |
| public ECFieldElement negate() |
| { |
| int[] z = Nat256.create(); |
| SecP256K1Field.negate(x, z); |
| return new SecP256K1FieldElement(z); |
| } |
| |
| public ECFieldElement square() |
| { |
| int[] z = Nat256.create(); |
| SecP256K1Field.square(x, z); |
| return new SecP256K1FieldElement(z); |
| } |
| |
| public ECFieldElement invert() |
| { |
| // return new SecP256K1FieldElement(toBigInteger().modInverse(Q)); |
| int[] z = Nat256.create(); |
| Mod.invert(SecP256K1Field.P, x, z); |
| return new SecP256K1FieldElement(z); |
| } |
| |
| // D.1.4 91 |
| /** |
| * 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 2^254 - 2^30 - 2^7 - 2^6 - 2^5 - 2^4 - 2^2 |
| * |
| * Breaking up the exponent's binary representation into "repunits", we get: |
| * { 223 1s } { 1 0s } { 22 1s } { 4 0s } { 2 1s } { 2 0s} |
| * |
| * Therefore we need an addition chain containing 2, 22, 223 (the lengths of the repunits) |
| * We use: 1, [2], 3, 6, 9, 11, [22], 44, 88, 176, 220, [223] |
| */ |
| |
| int[] x1 = this.x; |
| if (Nat256.isZero(x1) || Nat256.isOne(x1)) |
| { |
| return this; |
| } |
| |
| int[] x2 = Nat256.create(); |
| SecP256K1Field.square(x1, x2); |
| SecP256K1Field.multiply(x2, x1, x2); |
| int[] x3 = Nat256.create(); |
| SecP256K1Field.square(x2, x3); |
| SecP256K1Field.multiply(x3, x1, x3); |
| int[] x6 = Nat256.create(); |
| SecP256K1Field.squareN(x3, 3, x6); |
| SecP256K1Field.multiply(x6, x3, x6); |
| int[] x9 = x6; |
| SecP256K1Field.squareN(x6, 3, x9); |
| SecP256K1Field.multiply(x9, x3, x9); |
| int[] x11 = x9; |
| SecP256K1Field.squareN(x9, 2, x11); |
| SecP256K1Field.multiply(x11, x2, x11); |
| int[] x22 = Nat256.create(); |
| SecP256K1Field.squareN(x11, 11, x22); |
| SecP256K1Field.multiply(x22, x11, x22); |
| int[] x44 = x11; |
| SecP256K1Field.squareN(x22, 22, x44); |
| SecP256K1Field.multiply(x44, x22, x44); |
| int[] x88 = Nat256.create(); |
| SecP256K1Field.squareN(x44, 44, x88); |
| SecP256K1Field.multiply(x88, x44, x88); |
| int[] x176 = Nat256.create(); |
| SecP256K1Field.squareN(x88, 88, x176); |
| SecP256K1Field.multiply(x176, x88, x176); |
| int[] x220 = x88; |
| SecP256K1Field.squareN(x176, 44, x220); |
| SecP256K1Field.multiply(x220, x44, x220); |
| int[] x223 = x44; |
| SecP256K1Field.squareN(x220, 3, x223); |
| SecP256K1Field.multiply(x223, x3, x223); |
| |
| int[] t1 = x223; |
| SecP256K1Field.squareN(t1, 23, t1); |
| SecP256K1Field.multiply(t1, x22, t1); |
| SecP256K1Field.squareN(t1, 6, t1); |
| SecP256K1Field.multiply(t1, x2, t1); |
| SecP256K1Field.squareN(t1, 2, t1); |
| |
| int[] t2 = x2; |
| SecP256K1Field.square(t1, t2); |
| |
| return Nat256.eq(x1, t2) ? new SecP256K1FieldElement(t1) : null; |
| } |
| |
| public boolean equals(Object other) |
| { |
| if (other == this) |
| { |
| return true; |
| } |
| |
| if (!(other instanceof SecP256K1FieldElement)) |
| { |
| return false; |
| } |
| |
| SecP256K1FieldElement o = (SecP256K1FieldElement)other; |
| return Nat256.eq(x, o.x); |
| } |
| |
| public int hashCode() |
| { |
| return Q.hashCode() ^ Arrays.hashCode(x, 0, 8); |
| } |
| } |