* SubjectPublicKeyInfo ::= SEQUENCE {
* algorithm AlgorithmIdentifier,
* subjectPublicKey BIT STRING
* }
*
* AlgorithmIdentifier ::= SEQUENCE {
* algorithm OBJECT IDENTIFIER,
* parameters ANY DEFINED BY algorithm OPTIONAL
* }
*
* DhParams ::= SEQUENCE {
* p INTEGER, -- odd prime, p=jq +1
* g INTEGER, -- generator, g
* q INTEGER -- factor of p-1
* }
*
*
* The subjectPublicKey field, which is a BIT STRING, contains the * DER-encoded form of the DH public key as an INTEGER.
* ** DHPublicKey ::= INTEGER -- public key, y = g^x mod p **
* IMPORTANT: with RI's {@link javax.crypto.spec.DHGenParameterSpec}
* and {@link javax.crypto.spec.DHParameterSpec} classes, we may end up with
* Diffie-Hellman keys that have a null for the q
* parameter. RFC-2631 DOES NOT allow for an optional value for that
* parameter, hence we replace such null values with 0, and do
* the reverse in the corresponding decode method.
*
* @param key the {@link PublicKey} instance to encode. MUST be an instance of
* {@link GnuDHPublicKey}.
* @return the DER-encoded form of the ASN.1 representation of the
* SubjectPublicKeyInfo in an X.509 certificate.
* @throw InvalidParameterException if key is not an instance
* of {@link GnuDHPublicKey} or if an exception occurs during the
* marshalling process.
*/
public byte[] encodePublicKey(PublicKey key)
{
if (! (key instanceof GnuDHPublicKey))
throw new InvalidParameterException("Wrong key type");
DERValue derOID = new DERValue(DER.OBJECT_IDENTIFIER, DH_ALG_OID);
GnuDHPublicKey dhKey = (GnuDHPublicKey) key;
BigInteger p = dhKey.getParams().getP();
BigInteger g = dhKey.getParams().getG();
BigInteger q = dhKey.getQ();
if (q == null)
q = BigInteger.ZERO;
BigInteger y = dhKey.getY();
DERValue derP = new DERValue(DER.INTEGER, p);
DERValue derG = new DERValue(DER.INTEGER, g);
DERValue derQ = new DERValue(DER.INTEGER, q);
ArrayList params = new ArrayList(3);
params.add(derP);
params.add(derG);
params.add(derQ);
DERValue derParams = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE, params);
ArrayList algorithmID = new ArrayList(2);
algorithmID.add(derOID);
algorithmID.add(derParams);
DERValue derAlgorithmID = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE,
algorithmID);
DERValue derDHPublicKey = new DERValue(DER.INTEGER, y);
byte[] yBytes = derDHPublicKey.getEncoded();
DERValue derSPK = new DERValue(DER.BIT_STRING, new BitString(yBytes));
ArrayList spki = new ArrayList(2);
spki.add(derAlgorithmID);
spki.add(derSPK);
DERValue derSPKI = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE, spki);
byte[] result;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try
{
DERWriter.write(baos, derSPKI);
result = baos.toByteArray();
}
catch (IOException x)
{
InvalidParameterException e = new InvalidParameterException();
e.initCause(x);
throw e;
}
return result;
}
/**
* @throws InvalidParameterException ALWAYS.
*/
public byte[] encodePrivateKey(PrivateKey key)
{
throw new InvalidParameterException("Wrong format for private keys");
}
/**
* @param input the byte array to unmarshall into a valid DH
* {@link PublicKey} instance. MUST NOT be null.
* @return a new instance of a {@link GnuDHPublicKey} decoded from the
* SubjectPublicKeyInfo material in an X.509 certificate.
* @throw InvalidParameterException if an exception occurs during the
* unmarshalling process.
*/
public PublicKey decodePublicKey(byte[] input)
{
if (input == null)
throw new InvalidParameterException("Input bytes MUST NOT be null");
BigInteger p, g, q, y;
DERReader der = new DERReader(input);
try
{
DERValue derSPKI = der.read();
DerUtil.checkIsConstructed(derSPKI, "Wrong SubjectPublicKeyInfo field");
DERValue derAlgorithmID = der.read();
DerUtil.checkIsConstructed(derAlgorithmID, "Wrong AlgorithmIdentifier field");
DERValue derOID = der.read();
if (! (derOID.getValue() instanceof OID))
throw new InvalidParameterException("Wrong Algorithm field");
OID algOID = (OID) derOID.getValue();
if (! algOID.equals(DH_ALG_OID))
throw new InvalidParameterException("Unexpected OID: " + algOID);
DERValue derParams = der.read();
DerUtil.checkIsConstructed(derParams, "Wrong DH Parameters field");
DERValue val = der.read();
DerUtil.checkIsBigInteger(val, "Wrong P field");
p = (BigInteger) val.getValue();
val = der.read();
DerUtil.checkIsBigInteger(val, "Wrong G field");
g = (BigInteger) val.getValue();
val = der.read();
DerUtil.checkIsBigInteger(val, "Wrong Q field");
q = (BigInteger) val.getValue();
if (q.compareTo(BigInteger.ZERO) == 0)
q = null;
val = der.read();
if (! (val.getValue() instanceof BitString))
throw new InvalidParameterException("Wrong SubjectPublicKey field");
byte[] yBytes = ((BitString) val.getValue()).toByteArray();
DERReader dhPub = new DERReader(yBytes);
val = dhPub.read();
DerUtil.checkIsBigInteger(val, "Wrong Y field");
y = (BigInteger) val.getValue();
}
catch (IOException x)
{
InvalidParameterException e = new InvalidParameterException();
e.initCause(x);
throw e;
}
return new GnuDHPublicKey(Registry.X509_ENCODING_ID, q, p, g, y);
}
/**
* @throws InvalidParameterException ALWAYS.
*/
public PrivateKey decodePrivateKey(byte[] input)
{
throw new InvalidParameterException("Wrong format for private keys");
}
}