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The Bouncy Castle Java APIs for CMS, PKCS, EAC, TSP, CMP, CRMF, OCSP, and certificate generation. This jar contains APIs for JDK 1.5 and up. The APIs can be used in conjunction with a JCE/JCA provider such as the one provided with the Bouncy Castle Cryptography APIs.

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package org.bouncycastle.pqc.jcajce.provider.mceliece;

import java.io.IOException;
import java.security.PublicKey;

import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.crypto.params.AsymmetricKeyParameter;
import org.bouncycastle.pqc.asn1.McEliecePublicKey;
import org.bouncycastle.pqc.asn1.PQCObjectIdentifiers;
import org.bouncycastle.pqc.crypto.mceliece.McElieceKeyPairGenerator;
import org.bouncycastle.pqc.crypto.mceliece.McEliecePublicKeyParameters;
import org.bouncycastle.pqc.math.linearalgebra.GF2Matrix;

/**
 * This class implements a McEliece public key and is usually instantiated by
 * the {@link McElieceKeyPairGenerator} or {@link McElieceKeyFactorySpi}.
 */
public class BCMcEliecePublicKey
    implements PublicKey
{
    private static final long serialVersionUID = 1L;

    private McEliecePublicKeyParameters params;

    public BCMcEliecePublicKey(McEliecePublicKeyParameters params)
    {
        this.params = params;
    }

    /**
     * Return the name of the algorithm.
     *
     * @return "McEliece"
     */
    public String getAlgorithm()
    {
        return "McEliece";
    }

    /**
     * @return the length of the code
     */
    public int getN()
    {
        return params.getN();
    }

    /**
     * @return the dimension of the code
     */
    public int getK()
    {
        return params.getK();
    }

    /**
     * @return the error correction capability of the code
     */
    public int getT()
    {
        return params.getT();
    }

    /**
     * @return the generator matrix
     */
    public GF2Matrix getG()
    {
        return params.getG();
    }

    /**
     * @return a human readable form of the key
     */
    public String toString()
    {
        String result = "McEliecePublicKey:\n";
        result += " length of the code         : " + params.getN() + "\n";
        result += " error correction capability: " + params.getT() + "\n";
        result += " generator matrix           : " + params.getG();
        return result;
    }

    /**
     * Compare this key with another object.
     *
     * @param other the other object
     * @return the result of the comparison
     */
    public boolean equals(Object other)
    {
        if (other instanceof BCMcEliecePublicKey)
        {
            BCMcEliecePublicKey otherKey = (BCMcEliecePublicKey)other;

            return (params.getN() == otherKey.getN()) && (params.getT() == otherKey.getT()) && (params.getG().equals(otherKey.getG()));
        }

        return false;
    }

    /**
     * @return the hash code of this key
     */
    public int hashCode()
    {
        return 37 * (params.getN() + 37 * params.getT()) + params.getG().hashCode();
    }

    /**
     * Return the keyData to encode in the SubjectPublicKeyInfo structure.
     * 
     * The ASN.1 definition of the key structure is
     * 
     *      *       McEliecePublicKey ::= SEQUENCE {
     *         n           Integer      -- length of the code
     *         t           Integer      -- error correcting capability
     *         matrixG     OctetString  -- generator matrix as octet string
     *       }
     * 
     * @return the keyData to encode in the SubjectPublicKeyInfo structure
     */
    public byte[] getEncoded()
    {
        McEliecePublicKey key = new McEliecePublicKey(params.getN(), params.getT(), params.getG());
        AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(PQCObjectIdentifiers.mcEliece);

        try
        {
            SubjectPublicKeyInfo subjectPublicKeyInfo = new SubjectPublicKeyInfo(algorithmIdentifier, key);

            return subjectPublicKeyInfo.getEncoded();
        }
        catch (IOException e)
        {
            return null;
        }
    }

    public String getFormat()
    {
        return "X.509";
    }

    AsymmetricKeyParameter getKeyParams()
    {
        return params;
    }
}