https://openjdk.java.net/ 
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package sun.security.pkcs;

import java.io.*;
import java.util.Properties;
import java.math.*;
import java.security.Key;
import java.security.KeyRep;
import java.security.PrivateKey;
import java.security.KeyFactory;
import java.security.MessageDigest;
import java.security.Security;
import java.security.Provider;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;

import sun.security.util.HexDumpEncoder;
import sun.security.x509.*;
import sun.security.util.*;


Holds a PKCS#8 key, for example a private key

Author:Dave Brownell, Benjamin Renaud
/**
 * Holds a PKCS#8 key, for example a private key
 *
 * @author Dave Brownell
 * @author Benjamin Renaud
 */
public class PKCS8Key implements PrivateKey {

    
use serialVersionUID from JDK 1.1. for interoperability 
/** use serialVersionUID from JDK 1.1. for interoperability */
    private static final long serialVersionUID = -3836890099307167124L;

    /* The algorithm information (name, parameters, etc). */
    protected AlgorithmId algid;

    /* The key bytes, without the algorithm information */
    protected byte[] key;

    /* The encoded for the key. */
    protected byte[] encodedKey;

    /* The version for this key */
    public static final BigInteger version = BigInteger.ZERO;

    
Default constructor.  The key constructed must have its key
and algorithm initialized before it may be used, for example
by using decode.

/**
     * Default constructor.  The key constructed must have its key
     * and algorithm initialized before it may be used, for example
     * by using <code>decode</code>.
     */
    public PKCS8Key() { }

    /*
     * Build and initialize as a "default" key.  All PKCS#8 key
     * data is stored and transmitted losslessly, but no knowledge
     * about this particular algorithm is available.
     */
    private PKCS8Key (AlgorithmId algid, byte[] key)
    throws InvalidKeyException {
        this.algid = algid;
        this.key = key;
        encode();
    }

    /*
     * Binary backwards compatibility. New uses should call parseKey().
     */
    public static PKCS8Key parse (DerValue in) throws IOException {
        PrivateKey key;

        key = parseKey(in);
        if (key instanceof PKCS8Key)
            return (PKCS8Key)key;

        throw new IOException("Provider did not return PKCS8Key");
    }

    
Construct PKCS#8 subject public key from a DER value.  If
the runtime environment is configured with a specific class for
this kind of key, a subclass is returned.  Otherwise, a generic
PKCS8Key object is returned.

This mechanism gurantees that keys (and algorithms) may be
freely manipulated and transferred, without risk of losing
information.  Also, when a key (or algorithm) needs some special
handling, that specific need can be accomodated.

Params:
  • in – the DER-encoded SubjectPublicKeyInfo value
Throws:
/**
     * Construct PKCS#8 subject public key from a DER value.  If
     * the runtime environment is configured with a specific class for
     * this kind of key, a subclass is returned.  Otherwise, a generic
     * PKCS8Key object is returned.
     *
     * <P>This mechanism gurantees that keys (and algorithms) may be
     * freely manipulated and transferred, without risk of losing
     * information.  Also, when a key (or algorithm) needs some special
     * handling, that specific need can be accomodated.
     *
     * @param in the DER-encoded SubjectPublicKeyInfo value
     * @exception IOException on data format errors
     */
    public static PrivateKey parseKey (DerValue in) throws IOException
    {
        AlgorithmId algorithm;
        PrivateKey privKey;

        if (in.tag != DerValue.tag_Sequence)
            throw new IOException ("corrupt private key");

        BigInteger parsedVersion = in.data.getBigInteger();
        if (!version.equals(parsedVersion)) {
            throw new IOException("version mismatch: (supported: " +
                                  Debug.toHexString(version) +
                                  ", parsed: " +
                                  Debug.toHexString(parsedVersion));
        }

        algorithm = AlgorithmId.parse (in.data.getDerValue ());

        try {
            privKey = buildPKCS8Key (algorithm, in.data.getOctetString ());

        } catch (InvalidKeyException e) {
            throw new IOException("corrupt private key");
        }

        if (in.data.available () != 0)
            throw new IOException ("excess private key");
        return privKey;
    }

    
Parse the key bits.  This may be redefined by subclasses to take
advantage of structure within the key.  For example, RSA public
keys encapsulate two unsigned integers (modulus and exponent) as
DER values within the key bits; Diffie-Hellman and
DSS/DSA keys encapsulate a single unsigned integer.

This function is called when creating PKCS#8 SubjectPublicKeyInfo
values using the PKCS8Key member functions, such as parse
and decode.

Throws:
  • IOException – if a parsing error occurs.
  • InvalidKeyException – if the key encoding is invalid.
/**
     * Parse the key bits.  This may be redefined by subclasses to take
     * advantage of structure within the key.  For example, RSA public
     * keys encapsulate two unsigned integers (modulus and exponent) as
     * DER values within the <code>key</code> bits; Diffie-Hellman and
     * DSS/DSA keys encapsulate a single unsigned integer.
     *
     * <P>This function is called when creating PKCS#8 SubjectPublicKeyInfo
     * values using the PKCS8Key member functions, such as <code>parse</code>
     * and <code>decode</code>.
     *
     * @exception IOException if a parsing error occurs.
     * @exception InvalidKeyException if the key encoding is invalid.
     */
    protected void parseKeyBits () throws IOException, InvalidKeyException {
        encode();
    }

    /*
     * Factory interface, building the kind of key associated with this
     * specific algorithm ID or else returning this generic base class.
     * See the description above.
     */
    static PrivateKey buildPKCS8Key (AlgorithmId algid, byte[] key)
    throws IOException, InvalidKeyException
    {
        /*
         * Use the algid and key parameters to produce the ASN.1 encoding
         * of the key, which will then be used as the input to the
         * key factory.
         */
        DerOutputStream pkcs8EncodedKeyStream = new DerOutputStream();
        encode(pkcs8EncodedKeyStream, algid, key);
        PKCS8EncodedKeySpec pkcs8KeySpec
            = new PKCS8EncodedKeySpec(pkcs8EncodedKeyStream.toByteArray());

        try {
            // Instantiate the key factory of the appropriate algorithm
            KeyFactory keyFac = KeyFactory.getInstance(algid.getName());

            // Generate the private key
            return keyFac.generatePrivate(pkcs8KeySpec);
        } catch (NoSuchAlgorithmException e) {
            // Return generic PKCS8Key with opaque key data (see below)
        } catch (InvalidKeySpecException e) {
            // Return generic PKCS8Key with opaque key data (see below)
        }

        /*
         * Try again using JDK1.1-style for backwards compatibility.
         */
        String classname = "";
        try {
            Properties props;
            String keytype;
            Provider sunProvider;

            sunProvider = Security.getProvider("SUN");
            if (sunProvider == null)
                throw new InstantiationException();
            classname = sunProvider.getProperty("PrivateKey.PKCS#8." +
              algid.getName());
            if (classname == null) {
                throw new InstantiationException();
            }

            Class<?> keyClass = null;
            try {
                keyClass = Class.forName(classname);
            } catch (ClassNotFoundException e) {
                ClassLoader cl = ClassLoader.getSystemClassLoader();
                if (cl != null) {
                    keyClass = cl.loadClass(classname);
                }
            }

            @SuppressWarnings("deprecation")
            Object      inst = (keyClass != null) ? keyClass.newInstance() : null;
            PKCS8Key    result;

            if (inst instanceof PKCS8Key) {
                result = (PKCS8Key) inst;
                result.algid = algid;
                result.key = key;
                result.parseKeyBits();
                return result;
            }
        } catch (ClassNotFoundException e) {
        } catch (InstantiationException e) {
        } catch (IllegalAccessException e) {
            // this should not happen.
            throw new IOException (classname + " [internal error]");
        }

        PKCS8Key result = new PKCS8Key();
        result.algid = algid;
        result.key = key;
        return result;
    }

    
Returns the algorithm to be used with this key.

/**
     * Returns the algorithm to be used with this key.
     */
    public String getAlgorithm() {
        return algid.getName();
    }

    
Returns the algorithm ID to be used with this key.

/**
     * Returns the algorithm ID to be used with this key.
     */
    public AlgorithmId  getAlgorithmId () { return algid; }

    
PKCS#8 sequence on the DER output stream.

/**
     * PKCS#8 sequence on the DER output stream.
     */
    public final void encode(DerOutputStream out) throws IOException
    {
        encode(out, this.algid, this.key);
    }

    
Returns the DER-encoded form of the key as a byte array.

/**
     * Returns the DER-encoded form of the key as a byte array.
     */
    public synchronized byte[] getEncoded() {
        byte[] result = null;
        try {
            result = encode();
        } catch (InvalidKeyException e) {
        }
        return result;
    }

    
Returns the format for this key: "PKCS#8"

/**
     * Returns the format for this key: "PKCS#8"
     */
    public String getFormat() {
        return "PKCS#8";
    }

    
Returns the DER-encoded form of the key as a byte array.

Throws:
  • InvalidKeyException – if an encoding error occurs.
/**
     * Returns the DER-encoded form of the key as a byte array.
     *
     * @exception InvalidKeyException if an encoding error occurs.
     */
    public byte[] encode() throws InvalidKeyException {
        if (encodedKey == null) {
            try {
                DerOutputStream out;

                out = new DerOutputStream ();
                encode (out);
                encodedKey = out.toByteArray();

            } catch (IOException e) {
                throw new InvalidKeyException ("IOException : " +
                                               e.getMessage());
            }
        }
        return encodedKey.clone();
    }

    
Initialize an PKCS8Key object from an input stream.  The data
on that input stream must be encoded using DER, obeying the
PKCS#8 format: a sequence consisting of a version, an algorithm
ID and a bit string which holds the key.  (That bit string is
often used to encapsulate another DER encoded sequence.)

Subclasses should not normally redefine this method; they should
instead provide a parseKeyBits method to parse any
fields inside the key member.

Params:
  • in – an input stream with a DER-encoded PKCS#8
SubjectPublicKeyInfo value
Throws:
/**
     * Initialize an PKCS8Key object from an input stream.  The data
     * on that input stream must be encoded using DER, obeying the
     * PKCS#8 format: a sequence consisting of a version, an algorithm
     * ID and a bit string which holds the key.  (That bit string is
     * often used to encapsulate another DER encoded sequence.)
     *
     * <P>Subclasses should not normally redefine this method; they should
     * instead provide a <code>parseKeyBits</code> method to parse any
     * fields inside the <code>key</code> member.
     *
     * @param in an input stream with a DER-encoded PKCS#8
     * SubjectPublicKeyInfo value
     *
     * @exception InvalidKeyException if a parsing error occurs.
     */
    public void decode(InputStream in) throws InvalidKeyException
    {
        DerValue        val;

        try {
            val = new DerValue (in);
            if (val.tag != DerValue.tag_Sequence)
                throw new InvalidKeyException ("invalid key format");


            BigInteger version = val.data.getBigInteger();
            if (!version.equals(PKCS8Key.version)) {
                throw new IOException("version mismatch: (supported: " +
                                      Debug.toHexString(PKCS8Key.version) +
                                      ", parsed: " +
                                      Debug.toHexString(version));
            }
            algid = AlgorithmId.parse (val.data.getDerValue ());
            key = val.data.getOctetString ();
            parseKeyBits ();

            if (val.data.available () != 0)  {
                // OPTIONAL attributes not supported yet
            }

        } catch (IOException e) {
            throw new InvalidKeyException("IOException : " +
                                          e.getMessage());
        }
    }

    public void decode(byte[] encodedKey) throws InvalidKeyException {
        decode(new ByteArrayInputStream(encodedKey));
    }

    protected Object writeReplace() throws java.io.ObjectStreamException {
        return new KeyRep(KeyRep.Type.PRIVATE,
                        getAlgorithm(),
                        getFormat(),
                        getEncoded());
    }

    
Serialization read ... PKCS#8 keys serialize as
themselves, and they're parsed when they get read back.

/**
     * Serialization read ... PKCS#8 keys serialize as
     * themselves, and they're parsed when they get read back.
     */
    private void readObject (ObjectInputStream stream)
    throws IOException {

        try {
            decode(stream);

        } catch (InvalidKeyException e) {
            e.printStackTrace();
            throw new IOException("deserialized key is invalid: " +
                                  e.getMessage());
        }
    }

    /*
     * Produce PKCS#8 encoding from algorithm id and key material.
     */
    static void encode(DerOutputStream out, AlgorithmId algid, byte[] key)
        throws IOException {
            DerOutputStream tmp = new DerOutputStream();
            tmp.putInteger(version);
            algid.encode(tmp);
            tmp.putOctetString(key);
            out.write(DerValue.tag_Sequence, tmp);
    }

    
Compares two private keys. This returns false if the object with which
to compare is not of type Key.
Otherwise, the encoding of this key object is compared with the
encoding of the given key object.

Params:
  • object – the object with which to compare
Returns:true if this key has the same encoding as the
object argument; false otherwise.
/**
     * Compares two private keys. This returns false if the object with which
     * to compare is not of type <code>Key</code>.
     * Otherwise, the encoding of this key object is compared with the
     * encoding of the given key object.
     *
     * @param object the object with which to compare
     * @return <code>true</code> if this key has the same encoding as the
     * object argument; <code>false</code> otherwise.
     */
    public boolean equals(Object object) {
        if (this == object) {
            return true;
        }

        if (object instanceof Key) {

            // this encoding
            byte[] b1;
            if (encodedKey != null) {
                b1 = encodedKey;
            } else {
                b1 = getEncoded();
            }

            // that encoding
            byte[] b2 = ((Key)object).getEncoded();

            // time-constant comparison
            return MessageDigest.isEqual(b1, b2);
        }
        return false;
    }

    
Calculates a hash code value for this object. Objects
which are equal will also have the same hashcode.

/**
     * Calculates a hash code value for this object. Objects
     * which are equal will also have the same hashcode.
     */
    public int hashCode() {
        int retval = 0;
        byte[] b1 = getEncoded();

        for (int i = 1; i < b1.length; i++) {
            retval += b1[i] * i;
        }
        return(retval);
    }
}