120 lines
4.5 KiB
Java
120 lines
4.5 KiB
Java
package org.bouncycastle.pqc.crypto.mceliece;
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import java.math.BigInteger;
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import org.bouncycastle.pqc.math.linearalgebra.BigIntUtils;
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import org.bouncycastle.pqc.math.linearalgebra.GF2Vector;
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import org.bouncycastle.pqc.math.linearalgebra.IntegerFunctions;
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/* loaded from: classes6.dex */
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final class Conversions {
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private static final BigInteger ZERO = BigInteger.valueOf(0);
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private static final BigInteger ONE = BigInteger.valueOf(1);
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public static byte[] signConversion(int i, int i2, byte[] bArr) {
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if (i < i2) {
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throw new IllegalArgumentException("n < t");
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}
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BigInteger binomial = IntegerFunctions.binomial(i, i2);
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int bitLength = binomial.bitLength() - 1;
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int i3 = bitLength >> 3;
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int i4 = bitLength & 7;
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int i5 = 8;
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if (i4 == 0) {
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i3--;
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i4 = 8;
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}
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int i6 = i >> 3;
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int i7 = i & 7;
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if (i7 == 0) {
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i6--;
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} else {
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i5 = i7;
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}
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int i8 = i6 + 1;
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byte[] bArr2 = new byte[i8];
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if (bArr.length < i8) {
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System.arraycopy(bArr, 0, bArr2, 0, bArr.length);
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for (int length = bArr.length; length < i8; length++) {
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bArr2[length] = 0;
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}
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} else {
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System.arraycopy(bArr, 0, bArr2, 0, i6);
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bArr2[i6] = (byte) (bArr[i6] & ((1 << i5) - 1));
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}
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BigInteger bigInteger = ZERO;
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int i9 = i;
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for (int i10 = 0; i10 < i; i10++) {
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binomial = binomial.multiply(new BigInteger(Integer.toString(i9 - i2))).divide(new BigInteger(Integer.toString(i9)));
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i9--;
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if (((byte) (bArr2[i10 >>> 3] & (1 << (i10 & 7)))) != 0) {
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bigInteger = bigInteger.add(binomial);
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int i11 = i2 - 1;
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binomial = i9 == i11 ? ONE : binomial.multiply(new BigInteger(Integer.toString(i2))).divide(new BigInteger(Integer.toString(i9 - i11)));
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i2 = i11;
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}
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}
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int i12 = i3 + 1;
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byte[] bArr3 = new byte[i12];
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byte[] byteArray = bigInteger.toByteArray();
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if (byteArray.length < i12) {
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System.arraycopy(byteArray, 0, bArr3, 0, byteArray.length);
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for (int length2 = byteArray.length; length2 < i12; length2++) {
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bArr3[length2] = 0;
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}
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} else {
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System.arraycopy(byteArray, 0, bArr3, 0, i3);
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bArr3[i3] = (byte) (((1 << i4) - 1) & byteArray[i3]);
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}
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return bArr3;
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}
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public static GF2Vector encode(int i, int i2, byte[] bArr) {
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if (i < i2) {
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throw new IllegalArgumentException("n < t");
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}
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BigInteger binomial = IntegerFunctions.binomial(i, i2);
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BigInteger bigInteger = new BigInteger(1, bArr);
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if (bigInteger.compareTo(binomial) >= 0) {
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throw new IllegalArgumentException("Encoded number too large.");
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}
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GF2Vector gF2Vector = new GF2Vector(i);
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int i3 = i;
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for (int i4 = 0; i4 < i; i4++) {
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binomial = binomial.multiply(BigInteger.valueOf(i3 - i2)).divide(BigInteger.valueOf(i3));
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i3--;
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if (binomial.compareTo(bigInteger) <= 0) {
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gF2Vector.setBit(i4);
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bigInteger = bigInteger.subtract(binomial);
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int i5 = i2 - 1;
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binomial = i3 == i5 ? ONE : binomial.multiply(BigInteger.valueOf(i2)).divide(BigInteger.valueOf(i3 - i5));
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i2 = i5;
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}
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}
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return gF2Vector;
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}
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public static byte[] decode(int i, int i2, GF2Vector gF2Vector) {
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if (gF2Vector.getLength() != i || gF2Vector.getHammingWeight() != i2) {
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throw new IllegalArgumentException("vector has wrong length or hamming weight");
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}
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int[] vecArray = gF2Vector.getVecArray();
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BigInteger binomial = IntegerFunctions.binomial(i, i2);
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BigInteger bigInteger = ZERO;
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int i3 = i;
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for (int i4 = 0; i4 < i; i4++) {
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binomial = binomial.multiply(BigInteger.valueOf(i3 - i2)).divide(BigInteger.valueOf(i3));
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i3--;
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if ((vecArray[i4 >> 5] & (1 << (i4 & 31))) != 0) {
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bigInteger = bigInteger.add(binomial);
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int i5 = i2 - 1;
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binomial = i3 == i5 ? ONE : binomial.multiply(BigInteger.valueOf(i2)).divide(BigInteger.valueOf(i3 - i5));
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i2 = i5;
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}
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}
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return BigIntUtils.toMinimalByteArray(bigInteger);
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}
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private Conversions() {
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}
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}
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