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package com.sun.crypto.provider;

import java.io.IOException;
import java.security.AlgorithmParametersSpi;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidParameterSpecException;
import javax.crypto.spec.IvParameterSpec;
import sun.security.util.*;


This class implements the parameter set used with the ChaCha20-Poly1305
algorithm.  The parameter definition comes from
RFC 8103
and is defined according to the following ASN.1:

id-alg-AEADChaCha20Poly1305 OBJECT IDENTIFIER ::=
       { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
         pkcs9(9) smime(16) alg(3) 18 }
AEADChaCha20Poly1305Nonce ::= OCTET STRING (SIZE(12))


The AlgorithmParameters may be instantiated either by its name
("ChaCha20-Poly1305") or via its OID (1.2.840.113549.1.9.16.3.18)

/**
 * This class implements the parameter set used with the ChaCha20-Poly1305
 * algorithm.  The parameter definition comes from
 * <a href="https://tools.ietf.org/html/rfc8103"><i>RFC 8103</i></a>
 * and is defined according to the following ASN.1:
 *
 * <pre>
 * id-alg-AEADChaCha20Poly1305 OBJECT IDENTIFIER ::=
 *        { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
 *          pkcs9(9) smime(16) alg(3) 18 }
 *
 * AEADChaCha20Poly1305Nonce ::= OCTET STRING (SIZE(12))
 * </pre>
 *
 * The AlgorithmParameters may be instantiated either by its name
 * ("ChaCha20-Poly1305") or via its OID (1.2.840.113549.1.9.16.3.18)
 */
public final class ChaCha20Poly1305Parameters extends AlgorithmParametersSpi {

    private static final String DEFAULT_FMT = "ASN.1";
    private byte[] nonce;

    public ChaCha20Poly1305Parameters() {}

    
Initialize the ChaCha20Poly1305Parameters using an IvParameterSpec.

Params:
  • paramSpec – the IvParameterSpec used to configure this object.
Throws:
/**
     * Initialize the ChaCha20Poly1305Parameters using an IvParameterSpec.
     *
     * @param paramSpec the {@code IvParameterSpec} used to configure
     *      this object.
     *
     * @throws InvalidParameterSpecException if an object of a type other
     *      than {@code IvParameterSpec} is used.
     */
    @Override
    protected void engineInit(AlgorithmParameterSpec paramSpec)
        throws InvalidParameterSpecException {

        if (!(paramSpec instanceof IvParameterSpec)) {
            throw new InvalidParameterSpecException
                ("Inappropriate parameter specification");
        }
        IvParameterSpec ivps = (IvParameterSpec)paramSpec;

        // Obtain the nonce
        nonce = ivps.getIV();
        if (nonce.length != 12) {
            throw new InvalidParameterSpecException("ChaCha20-Poly1305 nonce" +
                    " must be 12 bytes in length");
        }
    }

    
Initialize the ChaCha20Poly1305Parameters from a DER encoded
parameter block.

Params:
  • encoded – the DER encoding of the nonce as an OCTET STRING.
Throws:
  • IOException – if the encoded nonce is not 12 bytes long or a DER
     decoding error occurs.
/**
     * Initialize the ChaCha20Poly1305Parameters from a DER encoded
     * parameter block.
     *
     * @param encoded the DER encoding of the nonce as an OCTET STRING.
     *
     * @throws IOException if the encoded nonce is not 12 bytes long or a DER
     *      decoding error occurs.
     */
    @Override
    protected void engineInit(byte[] encoded) throws IOException {
        DerValue val = new DerValue(encoded);

        // Get the nonce value
        nonce = val.getOctetString();
        if (nonce.length != 12) {
           throw new IOException(
                   "ChaCha20-Poly1305 nonce must be 12 bytes in length");
        }
    }

    
Initialize the ChaCha20Poly1305Parameters from a DER encoded
parameter block.

Params:
  • encoded – the DER encoding of the nonce and initial block counter.
  • decodingMethod – the decoding method.  The only currently accepted
     value is "ASN.1"
Throws:
  • IOException – if the encoded nonce is not 12 bytes long, a DER
     decoding error occurs, or an unsupported decoding method is
     provided.
/**
     * Initialize the ChaCha20Poly1305Parameters from a DER encoded
     * parameter block.
     *
     * @param encoded the DER encoding of the nonce and initial block counter.
     * @param decodingMethod the decoding method.  The only currently accepted
     *      value is "ASN.1"
     *
     * @throws IOException if the encoded nonce is not 12 bytes long, a DER
     *      decoding error occurs, or an unsupported decoding method is
     *      provided.
     */
    @Override
    protected void engineInit(byte[] encoded, String decodingMethod)
            throws IOException {
        if (decodingMethod == null ||
                decodingMethod.equalsIgnoreCase(DEFAULT_FMT)) {
            engineInit(encoded);
        } else {
            throw new IOException("Unsupported parameter format: " +
                    decodingMethod);
        }
    }

    
Return an IvParameterSpec with the same parameters as those
held in this object.

Params:
  • paramSpec – the class name of the spec. In this case it should be IvParameterSpec.class.
Throws:
Returns:a IvParameterSpec object containing the nonce value held in this object.
/**
     * Return an IvParameterSpec with the same parameters as those
     * held in this object.
     *
     * @param paramSpec the class name of the spec.  In this case it should
     *      be {@code IvParameterSpec.class}.
     *
     * @return a {@code IvParameterSpec} object containing the nonce
     *      value held in this object.
     *
     * @throws InvalidParameterSpecException if a class other than
     *      {@code IvParameterSpec.class} was specified in the paramSpec
     *      parameter.
     */
    @Override
    protected <T extends AlgorithmParameterSpec>
            T engineGetParameterSpec(Class<T> paramSpec)
        throws InvalidParameterSpecException {

        if (IvParameterSpec.class.isAssignableFrom(paramSpec)) {
            return paramSpec.cast(new IvParameterSpec(nonce));
        } else {
            throw new InvalidParameterSpecException
                ("Inappropriate parameter specification");
        }
    }

    
Return the encoded parameters in ASN.1 form.

Throws:
Returns:a byte array containing the DER-encoding for the
     ChaCha20-Poly1305 parameters.  This will be the nonce
     encoded as a DER OCTET STRING.
/**
     * Return the encoded parameters in ASN.1 form.
     *
     * @return a byte array containing the DER-encoding for the
     *      ChaCha20-Poly1305 parameters.  This will be the nonce
     *      encoded as a DER OCTET STRING.
     *
     * @throws IOException if any DER encoding error occurs.
     */
    @Override
    protected byte[] engineGetEncoded() throws IOException {
        DerOutputStream out = new DerOutputStream();
        out.write(DerValue.tag_OctetString, nonce);
        return out.toByteArray();
    }

    
Return the encoded parameters in ASN.1 form.

Params:
  • encodingMethod – the encoding method to be used. This parameter must be "ASN.1" as it is the only currently supported encoding format. If the parameter is null then the default encoding format will be used.
Throws:
  • IOException – if any DER encoding error occurs or an unsupported
     encoding method is provided.
Returns:a byte array containing the DER-encoding for the
     ChaCha20-Poly1305 parameters.
/**
     * Return the encoded parameters in ASN.1 form.
     *
     * @param encodingMethod the encoding method to be used.  This parameter
     *      must be "ASN.1" as it is the only currently supported encoding
     *      format.  If the parameter is {@code null} then the default
     *      encoding format will be used.
     *
     * @return a byte array containing the DER-encoding for the
     *      ChaCha20-Poly1305 parameters.
     *
     * @throws IOException if any DER encoding error occurs or an unsupported
     *      encoding method is provided.
     */
    @Override
    protected byte[] engineGetEncoded(String encodingMethod)
        throws IOException {
        if (encodingMethod == null ||
                encodingMethod.equalsIgnoreCase(DEFAULT_FMT)) {
            return engineGetEncoded();
        } else {
            throw new IOException("Unsupported encoding format: " +
                    encodingMethod);
        }
    }

    
Creates a formatted string describing the parameters.

Returns:a string representation of the ChaCha20 parameters.
/**
     * Creates a formatted string describing the parameters.
     *
     * @return a string representation of the ChaCha20 parameters.
     */
    @Override
    protected String engineToString() {
        String LINE_SEP = System.lineSeparator();
        HexDumpEncoder encoder = new HexDumpEncoder();
        StringBuilder sb = new StringBuilder(LINE_SEP + "nonce:" +
                LINE_SEP + "[" + encoder.encodeBuffer(nonce) + "]");
        return sb.toString();
    }
}