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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8. Note: this package includes the NTRU encryption algorithms.

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package org.bouncycastle.asn1;

import java.io.IOException;
import java.math.BigInteger;

import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.Properties;

/**
 * Class representing the ASN.1 INTEGER type.
 */
public class ASN1Integer
    extends ASN1Primitive
{
    private final byte[] bytes;

    /**
     * Return an integer from the passed in object.
     *
     * @param obj an ASN1Integer or an object that can be converted into one.
     * @return an ASN1Integer instance.
     * @throws IllegalArgumentException if the object cannot be converted.
     */
    public static ASN1Integer getInstance(
        Object obj)
    {
        if (obj == null || obj instanceof ASN1Integer)
        {
            return (ASN1Integer)obj;
        }

        if (obj instanceof byte[])
        {
            try
            {
                return (ASN1Integer)fromByteArray((byte[])obj);
            }
            catch (Exception e)
            {
                throw new IllegalArgumentException("encoding error in getInstance: " + e.toString());
            }
        }

        throw new IllegalArgumentException("illegal object in getInstance: " + obj.getClass().getName());
    }

    /**
     * Return an Integer from a tagged object.
     *
     * @param obj      the tagged object holding the object we want
     * @param explicit true if the object is meant to be explicitly
     *                 tagged false otherwise.
     * @return an ASN1Integer instance.
     * @throws IllegalArgumentException if the tagged object cannot
     * be converted.
     */
    public static ASN1Integer getInstance(
        ASN1TaggedObject obj,
        boolean explicit)
    {
        ASN1Primitive o = obj.getObject();

        if (explicit || o instanceof ASN1Integer)
        {
            return getInstance(o);
        }
        else
        {
            return new ASN1Integer(ASN1OctetString.getInstance(o).getOctets());
        }
    }

    /**
     * Construct an INTEGER from the passed in long value.
     *
     * @param value the long representing the value desired.
     */
    public ASN1Integer(
        long value)
    {
        bytes = BigInteger.valueOf(value).toByteArray();
    }

    /**
     * Construct an INTEGER from the passed in BigInteger value.
     *
     * @param value the BigInteger representing the value desired.
     */
    public ASN1Integer(
        BigInteger value)
    {
        bytes = value.toByteArray();
    }

    /**
     * Construct an INTEGER from the passed in byte array.
     *
     * 

* NB: Strict Validation applied by default. *

*

* It has turned out that there are still a few applications that struggle with * the ASN.1 BER encoding rules for an INTEGER as described in: * * https://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf * Section 8.3.2. *

*

* Users can set the 'org.bouncycastle.asn1.allow_unsafe_integer' to 'true' * and a looser validation will be applied. Users must recognise that this is * not ideal and may pave the way for an exploit based around a faulty encoding * in the future. *

* * @param bytes the byte array representing a 2's complement encoding of a BigInteger. */ public ASN1Integer( byte[] bytes) { this(bytes, true); } ASN1Integer(byte[] bytes, boolean clone) { // Apply loose validation, see note in public constructor ANS1Integer(byte[]) if (!Properties.isOverrideSet("org.bouncycastle.asn1.allow_unsafe_integer")) { if (isMalformed(bytes)) { throw new IllegalArgumentException("malformed integer"); } } this.bytes = (clone) ? Arrays.clone(bytes) : bytes; } /** * Apply the correct validation for an INTEGER primitive following the BER rules. * * @param bytes The raw encoding of the integer. * @return true if the (in)put fails this validation. */ static boolean isMalformed(byte[] bytes) { if (bytes.length > 1) { if (bytes[0] == 0 && (bytes[1] & 0x80) == 0) { return true; } if (bytes[0] == (byte)0xff && (bytes[1] & 0x80) != 0) { return true; } } return false; } public BigInteger getValue() { return new BigInteger(bytes); } /** * in some cases positive values get crammed into a space, * that's not quite big enough... * * @return the BigInteger that results from treating this ASN.1 INTEGER as unsigned. */ public BigInteger getPositiveValue() { return new BigInteger(1, bytes); } boolean isConstructed() { return false; } int encodedLength() { return 1 + StreamUtil.calculateBodyLength(bytes.length) + bytes.length; } void encode( ASN1OutputStream out) throws IOException { out.writeEncoded(BERTags.INTEGER, bytes); } public int hashCode() { int value = 0; for (int i = 0; i != bytes.length; i++) { value ^= (bytes[i] & 0xff) << (i % 4); } return value; } boolean asn1Equals( ASN1Primitive o) { if (!(o instanceof ASN1Integer)) { return false; } ASN1Integer other = (ASN1Integer)o; return Arrays.areEqual(bytes, other.bytes); } public String toString() { return getValue().toString(); } }




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