| /* 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.Nat224; |
| import com.android.org.bouncycastle.util.Arrays; |
| import com.android.org.bouncycastle.util.encoders.Hex; |
| |
| /** |
| * @hide This class is not part of the Android public SDK API |
| */ |
| public class SecP224K1FieldElement extends ECFieldElement.AbstractFp |
| { |
| public static final BigInteger Q = new BigInteger(1, |
| Hex.decodeStrict("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFE56D")); |
| |
| // Calculated as ECConstants.TWO.modPow(Q.shiftRight(2), Q) |
| private static final int[] PRECOMP_POW2 = new int[]{ 0x33bfd202, 0xdcfad133, 0x2287624a, 0xc3811ba8, |
| 0xa85558fc, 0x1eaef5d7, 0x8edf154c }; |
| |
| protected int[] x; |
| |
| public SecP224K1FieldElement(BigInteger x) |
| { |
| if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0) |
| { |
| throw new IllegalArgumentException("x value invalid for SecP224K1FieldElement"); |
| } |
| |
| this.x = SecP224K1Field.fromBigInteger(x); |
| } |
| |
| public SecP224K1FieldElement() |
| { |
| this.x = Nat224.create(); |
| } |
| |
| protected SecP224K1FieldElement(int[] x) |
| { |
| this.x = x; |
| } |
| |
| public boolean isZero() |
| { |
| return Nat224.isZero(x); |
| } |
| |
| public boolean isOne() |
| { |
| return Nat224.isOne(x); |
| } |
| |
| public boolean testBitZero() |
| { |
| return Nat224.getBit(x, 0) == 1; |
| } |
| |
| public BigInteger toBigInteger() |
| { |
| return Nat224.toBigInteger(x); |
| } |
| |
| public String getFieldName() |
| { |
| return "SecP224K1Field"; |
| } |
| |
| public int getFieldSize() |
| { |
| return Q.bitLength(); |
| } |
| |
| public ECFieldElement add(ECFieldElement b) |
| { |
| int[] z = Nat224.create(); |
| SecP224K1Field.add(x, ((SecP224K1FieldElement)b).x, z); |
| return new SecP224K1FieldElement(z); |
| } |
| |
| public ECFieldElement addOne() |
| { |
| int[] z = Nat224.create(); |
| SecP224K1Field.addOne(x, z); |
| return new SecP224K1FieldElement(z); |
| } |
| |
| public ECFieldElement subtract(ECFieldElement b) |
| { |
| int[] z = Nat224.create(); |
| SecP224K1Field.subtract(x, ((SecP224K1FieldElement)b).x, z); |
| return new SecP224K1FieldElement(z); |
| } |
| |
| public ECFieldElement multiply(ECFieldElement b) |
| { |
| int[] z = Nat224.create(); |
| SecP224K1Field.multiply(x, ((SecP224K1FieldElement)b).x, z); |
| return new SecP224K1FieldElement(z); |
| } |
| |
| public ECFieldElement divide(ECFieldElement b) |
| { |
| // return multiply(b.invert()); |
| int[] z = Nat224.create(); |
| SecP224K1Field.inv(((SecP224K1FieldElement)b).x, z); |
| SecP224K1Field.multiply(z, x, z); |
| return new SecP224K1FieldElement(z); |
| } |
| |
| public ECFieldElement negate() |
| { |
| int[] z = Nat224.create(); |
| SecP224K1Field.negate(x, z); |
| return new SecP224K1FieldElement(z); |
| } |
| |
| public ECFieldElement square() |
| { |
| int[] z = Nat224.create(); |
| SecP224K1Field.square(x, z); |
| return new SecP224K1FieldElement(z); |
| } |
| |
| public ECFieldElement invert() |
| { |
| // return new SecP224K1FieldElement(toBigInteger().modInverse(Q)); |
| int[] z = Nat224.create(); |
| SecP224K1Field.inv(x, z); |
| return new SecP224K1FieldElement(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() |
| { |
| /* |
| * Q == 8m + 5, so we use Pocklington's method for this case. |
| * |
| * First, raise this element to the exponent 2^221 - 2^29 - 2^9 - 2^8 - 2^6 - 2^4 - 2^1 (i.e. m + 1) |
| * |
| * Breaking up the exponent's binary representation into "repunits", we get: |
| * { 191 1s } { 1 0s } { 19 1s } { 2 0s } { 1 1s } { 1 0s } { 1 1s } { 1 0s } { 3 1s } { 1 0s } |
| * |
| * Therefore we need an addition chain containing 1, 3, 19, 191 (the lengths of the repunits) |
| * We use: [1], 2, [3], 4, 8, 11, [19], 23, 42, 84, 107, [191] |
| */ |
| |
| int[] x1 = this.x; |
| if (Nat224.isZero(x1) || Nat224.isOne(x1)) |
| { |
| return this; |
| } |
| |
| int[] x2 = Nat224.create(); |
| SecP224K1Field.square(x1, x2); |
| SecP224K1Field.multiply(x2, x1, x2); |
| int[] x3 = x2; |
| SecP224K1Field.square(x2, x3); |
| SecP224K1Field.multiply(x3, x1, x3); |
| int[] x4 = Nat224.create(); |
| SecP224K1Field.square(x3, x4); |
| SecP224K1Field.multiply(x4, x1, x4); |
| int[] x8 = Nat224.create(); |
| SecP224K1Field.squareN(x4, 4, x8); |
| SecP224K1Field.multiply(x8, x4, x8); |
| int[] x11 = Nat224.create(); |
| SecP224K1Field.squareN(x8, 3, x11); |
| SecP224K1Field.multiply(x11, x3, x11); |
| int[] x19 = x11; |
| SecP224K1Field.squareN(x11, 8, x19); |
| SecP224K1Field.multiply(x19, x8, x19); |
| int[] x23 = x8; |
| SecP224K1Field.squareN(x19, 4, x23); |
| SecP224K1Field.multiply(x23, x4, x23); |
| int[] x42 = x4; |
| SecP224K1Field.squareN(x23, 19, x42); |
| SecP224K1Field.multiply(x42, x19, x42); |
| int[] x84 = Nat224.create(); |
| SecP224K1Field.squareN(x42, 42, x84); |
| SecP224K1Field.multiply(x84, x42, x84); |
| int[] x107 = x42; |
| SecP224K1Field.squareN(x84, 23, x107); |
| SecP224K1Field.multiply(x107, x23, x107); |
| int[] x191 = x23; |
| SecP224K1Field.squareN(x107, 84, x191); |
| SecP224K1Field.multiply(x191, x84, x191); |
| |
| int[] t1 = x191; |
| SecP224K1Field.squareN(t1, 20, t1); |
| SecP224K1Field.multiply(t1, x19, t1); |
| SecP224K1Field.squareN(t1, 3, t1); |
| SecP224K1Field.multiply(t1, x1, t1); |
| SecP224K1Field.squareN(t1, 2, t1); |
| SecP224K1Field.multiply(t1, x1, t1); |
| SecP224K1Field.squareN(t1, 4, t1); |
| SecP224K1Field.multiply(t1, x3, t1); |
| SecP224K1Field.square(t1, t1); |
| |
| int[] t2 = x84; |
| SecP224K1Field.square(t1, t2); |
| |
| if (Nat224.eq(x1, t2)) |
| { |
| return new SecP224K1FieldElement(t1); |
| } |
| |
| /* |
| * If the first guess is incorrect, we multiply by a precomputed power of 2 to get the second guess, |
| * which is ((4x)^(m + 1))/2 mod Q |
| */ |
| SecP224K1Field.multiply(t1, PRECOMP_POW2, t1); |
| |
| SecP224K1Field.square(t1, t2); |
| |
| if (Nat224.eq(x1, t2)) |
| { |
| return new SecP224K1FieldElement(t1); |
| } |
| |
| return null; |
| } |
| |
| public boolean equals(Object other) |
| { |
| if (other == this) |
| { |
| return true; |
| } |
| |
| if (!(other instanceof SecP224K1FieldElement)) |
| { |
| return false; |
| } |
| |
| SecP224K1FieldElement o = (SecP224K1FieldElement)other; |
| return Nat224.eq(x, o.x); |
| } |
| |
| public int hashCode() |
| { |
| return Q.hashCode() ^ Arrays.hashCode(x, 0, 7); |
| } |
| } |