| 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.Nat128; |
| import org.bouncycastle.util.Arrays; |
| |
| public class SecP128R1FieldElement extends ECFieldElement.AbstractFp |
| { |
| public static final BigInteger Q = SecP128R1Curve.q; |
| |
| protected int[] x; |
| |
| public SecP128R1FieldElement(BigInteger x) |
| { |
| if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0) |
| { |
| throw new IllegalArgumentException("x value invalid for SecP128R1FieldElement"); |
| } |
| |
| this.x = SecP128R1Field.fromBigInteger(x); |
| } |
| |
| public SecP128R1FieldElement() |
| { |
| this.x = Nat128.create(); |
| } |
| |
| protected SecP128R1FieldElement(int[] x) |
| { |
| this.x = x; |
| } |
| |
| public boolean isZero() |
| { |
| return Nat128.isZero(x); |
| } |
| |
| public boolean isOne() |
| { |
| return Nat128.isOne(x); |
| } |
| |
| public boolean testBitZero() |
| { |
| return Nat128.getBit(x, 0) == 1; |
| } |
| |
| public BigInteger toBigInteger() |
| { |
| return Nat128.toBigInteger(x); |
| } |
| |
| public String getFieldName() |
| { |
| return "SecP128R1Field"; |
| } |
| |
| public int getFieldSize() |
| { |
| return Q.bitLength(); |
| } |
| |
| public ECFieldElement add(ECFieldElement b) |
| { |
| int[] z = Nat128.create(); |
| SecP128R1Field.add(x, ((SecP128R1FieldElement)b).x, z); |
| return new SecP128R1FieldElement(z); |
| } |
| |
| public ECFieldElement addOne() |
| { |
| int[] z = Nat128.create(); |
| SecP128R1Field.addOne(x, z); |
| return new SecP128R1FieldElement(z); |
| } |
| |
| public ECFieldElement subtract(ECFieldElement b) |
| { |
| int[] z = Nat128.create(); |
| SecP128R1Field.subtract(x, ((SecP128R1FieldElement)b).x, z); |
| return new SecP128R1FieldElement(z); |
| } |
| |
| public ECFieldElement multiply(ECFieldElement b) |
| { |
| int[] z = Nat128.create(); |
| SecP128R1Field.multiply(x, ((SecP128R1FieldElement)b).x, z); |
| return new SecP128R1FieldElement(z); |
| } |
| |
| public ECFieldElement divide(ECFieldElement b) |
| { |
| // return multiply(b.invert()); |
| int[] z = Nat128.create(); |
| Mod.invert(SecP128R1Field.P, ((SecP128R1FieldElement)b).x, z); |
| SecP128R1Field.multiply(z, x, z); |
| return new SecP128R1FieldElement(z); |
| } |
| |
| public ECFieldElement negate() |
| { |
| int[] z = Nat128.create(); |
| SecP128R1Field.negate(x, z); |
| return new SecP128R1FieldElement(z); |
| } |
| |
| public ECFieldElement square() |
| { |
| int[] z = Nat128.create(); |
| SecP128R1Field.square(x, z); |
| return new SecP128R1FieldElement(z); |
| } |
| |
| public ECFieldElement invert() |
| { |
| // return new SecP128R1FieldElement(toBigInteger().modInverse(Q)); |
| int[] z = Nat128.create(); |
| Mod.invert(SecP128R1Field.P, x, z); |
| return new SecP128R1FieldElement(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 2^126 - 2^95 |
| * |
| * Breaking up the exponent's binary representation into "repunits", we get: |
| * { 31 1s } { 95 0s } |
| * |
| * Therefore we need an addition chain containing 31 (the length of the repunit) We use: |
| * 1, 2, 4, 8, 10, 20, 30, [31] |
| */ |
| |
| int[] x1 = this.x; |
| if (Nat128.isZero(x1) || Nat128.isOne(x1)) |
| { |
| return this; |
| } |
| |
| int[] x2 = Nat128.create(); |
| SecP128R1Field.square(x1, x2); |
| SecP128R1Field.multiply(x2, x1, x2); |
| int[] x4 = Nat128.create(); |
| SecP128R1Field.squareN(x2, 2, x4); |
| SecP128R1Field.multiply(x4, x2, x4); |
| int[] x8 = Nat128.create(); |
| SecP128R1Field.squareN(x4, 4, x8); |
| SecP128R1Field.multiply(x8, x4, x8); |
| int[] x10 = x4; |
| SecP128R1Field.squareN(x8, 2, x10); |
| SecP128R1Field.multiply(x10, x2, x10); |
| int[] x20 = x2; |
| SecP128R1Field.squareN(x10, 10, x20); |
| SecP128R1Field.multiply(x20, x10, x20); |
| int[] x30 = x8; |
| SecP128R1Field.squareN(x20, 10, x30); |
| SecP128R1Field.multiply(x30, x10, x30); |
| int[] x31 = x10; |
| SecP128R1Field.square(x30, x31); |
| SecP128R1Field.multiply(x31, x1, x31); |
| |
| int[] t1 = x31; |
| SecP128R1Field.squareN(t1, 95, t1); |
| |
| int[] t2 = x30; |
| SecP128R1Field.square(t1, t2); |
| |
| return Nat128.eq(x1, t2) ? new SecP128R1FieldElement(t1) : null; |
| } |
| |
| public boolean equals(Object other) |
| { |
| if (other == this) |
| { |
| return true; |
| } |
| |
| if (!(other instanceof SecP128R1FieldElement)) |
| { |
| return false; |
| } |
| |
| SecP128R1FieldElement o = (SecP128R1FieldElement)other; |
| return Nat128.eq(x, o.x); |
| } |
| |
| public int hashCode() |
| { |
| return Q.hashCode() ^ Arrays.hashCode(x, 0, 4); |
| } |
| } |