| 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.Nat160; |
| import org.bouncycastle.util.Arrays; |
| |
| public class SecP160R2FieldElement extends ECFieldElement |
| { |
| public static final BigInteger Q = SecP160R2Curve.q; |
| |
| protected int[] x; |
| |
| public SecP160R2FieldElement(BigInteger x) |
| { |
| if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0) |
| { |
| throw new IllegalArgumentException("x value invalid for SecP160R2FieldElement"); |
| } |
| |
| this.x = SecP160R2Field.fromBigInteger(x); |
| } |
| |
| public SecP160R2FieldElement() |
| { |
| this.x = Nat160.create(); |
| } |
| |
| protected SecP160R2FieldElement(int[] x) |
| { |
| this.x = x; |
| } |
| |
| public boolean isZero() |
| { |
| return Nat160.isZero(x); |
| } |
| |
| public boolean isOne() |
| { |
| return Nat160.isOne(x); |
| } |
| |
| public boolean testBitZero() |
| { |
| return Nat160.getBit(x, 0) == 1; |
| } |
| |
| public BigInteger toBigInteger() |
| { |
| return Nat160.toBigInteger(x); |
| } |
| |
| public String getFieldName() |
| { |
| return "SecP160R2Field"; |
| } |
| |
| public int getFieldSize() |
| { |
| return Q.bitLength(); |
| } |
| |
| public ECFieldElement add(ECFieldElement b) |
| { |
| int[] z = Nat160.create(); |
| SecP160R2Field.add(x, ((SecP160R2FieldElement)b).x, z); |
| return new SecP160R2FieldElement(z); |
| } |
| |
| public ECFieldElement addOne() |
| { |
| int[] z = Nat160.create(); |
| SecP160R2Field.addOne(x, z); |
| return new SecP160R2FieldElement(z); |
| } |
| |
| public ECFieldElement subtract(ECFieldElement b) |
| { |
| int[] z = Nat160.create(); |
| SecP160R2Field.subtract(x, ((SecP160R2FieldElement)b).x, z); |
| return new SecP160R2FieldElement(z); |
| } |
| |
| public ECFieldElement multiply(ECFieldElement b) |
| { |
| int[] z = Nat160.create(); |
| SecP160R2Field.multiply(x, ((SecP160R2FieldElement)b).x, z); |
| return new SecP160R2FieldElement(z); |
| } |
| |
| public ECFieldElement divide(ECFieldElement b) |
| { |
| // return multiply(b.invert()); |
| int[] z = Nat160.create(); |
| Mod.invert(SecP160R2Field.P, ((SecP160R2FieldElement)b).x, z); |
| SecP160R2Field.multiply(z, x, z); |
| return new SecP160R2FieldElement(z); |
| } |
| |
| public ECFieldElement negate() |
| { |
| int[] z = Nat160.create(); |
| SecP160R2Field.negate(x, z); |
| return new SecP160R2FieldElement(z); |
| } |
| |
| public ECFieldElement square() |
| { |
| int[] z = Nat160.create(); |
| SecP160R2Field.square(x, z); |
| return new SecP160R2FieldElement(z); |
| } |
| |
| public ECFieldElement invert() |
| { |
| // return new SecP160R2FieldElement(toBigInteger().modInverse(Q)); |
| int[] z = Nat160.create(); |
| Mod.invert(SecP160R2Field.P, x, z); |
| return new SecP160R2FieldElement(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 2^158 - 2^30 - 2^12 - 2^10 - 2^7 - 2^6 - 2^5 - 2^1 - 2^0 |
| * |
| * Breaking up the exponent's binary representation into "repunits", we get: { 127 1s } { 1 |
| * 0s } { 17 1s } { 1 0s } { 1 1s } { 1 0s } { 2 1s } { 3 0s } { 3 1s } { 1 0s } { 1 1s } |
| * |
| * Therefore we need an addition chain containing 1, 2, 3, 17, 127 (the lengths of the repunits) |
| * We use: [1], [2], [3], 4, 7, 14, [17], 31, 62, 124, [127] |
| */ |
| |
| int[] x1 = this.x; |
| if (Nat160.isZero(x1) || Nat160.isOne(x1)) |
| { |
| return this; |
| } |
| |
| int[] x2 = Nat160.create(); |
| SecP160R2Field.square(x1, x2); |
| SecP160R2Field.multiply(x2, x1, x2); |
| int[] x3 = Nat160.create(); |
| SecP160R2Field.square(x2, x3); |
| SecP160R2Field.multiply(x3, x1, x3); |
| int[] x4 = Nat160.create(); |
| SecP160R2Field.square(x3, x4); |
| SecP160R2Field.multiply(x4, x1, x4); |
| int[] x7 = Nat160.create(); |
| SecP160R2Field.squareN(x4, 3, x7); |
| SecP160R2Field.multiply(x7, x3, x7); |
| int[] x14 = x4; |
| SecP160R2Field.squareN(x7, 7, x14); |
| SecP160R2Field.multiply(x14, x7, x14); |
| int[] x17 = x7; |
| SecP160R2Field.squareN(x14, 3, x17); |
| SecP160R2Field.multiply(x17, x3, x17); |
| int[] x31 = Nat160.create(); |
| SecP160R2Field.squareN(x17, 14, x31); |
| SecP160R2Field.multiply(x31, x14, x31); |
| int[] x62 = x14; |
| SecP160R2Field.squareN(x31, 31, x62); |
| SecP160R2Field.multiply(x62, x31, x62); |
| int[] x124 = x31; |
| SecP160R2Field.squareN(x62, 62, x124); |
| SecP160R2Field.multiply(x124, x62, x124); |
| int[] x127 = x62; |
| SecP160R2Field.squareN(x124, 3, x127); |
| SecP160R2Field.multiply(x127, x3, x127); |
| |
| int[] t1 = x127; |
| SecP160R2Field.squareN(t1, 18, t1); |
| SecP160R2Field.multiply(t1, x17, t1); |
| SecP160R2Field.squareN(t1, 2, t1); |
| SecP160R2Field.multiply(t1, x1, t1); |
| SecP160R2Field.squareN(t1, 3, t1); |
| SecP160R2Field.multiply(t1, x2, t1); |
| SecP160R2Field.squareN(t1, 6, t1); |
| SecP160R2Field.multiply(t1, x3, t1); |
| SecP160R2Field.squareN(t1, 2, t1); |
| SecP160R2Field.multiply(t1, x1, t1); |
| |
| int[] t2 = x2; |
| SecP160R2Field.square(t1, t2); |
| |
| return Nat160.eq(x1, t2) ? new SecP160R2FieldElement(t1) : null; |
| } |
| |
| public boolean equals(Object other) |
| { |
| if (other == this) |
| { |
| return true; |
| } |
| |
| if (!(other instanceof SecP160R2FieldElement)) |
| { |
| return false; |
| } |
| |
| SecP160R2FieldElement o = (SecP160R2FieldElement)other; |
| return Nat160.eq(x, o.x); |
| } |
| |
| public int hashCode() |
| { |
| return Q.hashCode() ^ Arrays.hashCode(x, 0, 5); |
| } |
| } |