The authority key identifier extension provides a means of * identifying the particular public key used to sign a certificate. * This extension would be used where an issuer has multiple signing * keys (either due to multiple concurrent key pairs or due to * changeover). *
* The ASN.1 syntax for this is: *
* AuthorityKeyIdentifier ::= SEQUENCE {
* keyIdentifier [0] KeyIdentifier OPTIONAL,
* authorityCertIssuer [1] GeneralNames OPTIONAL,
* authorityCertSerialNumber [2] CertificateSerialNumber OPTIONAL
* }
* KeyIdentifier ::= OCTET STRING
*
* @author Amit Kapoor
* @author Hemma Prafullchandra
* @see Extension
*/
public class AuthorityKeyIdentifierExtension extends Extension {
public static final String NAME = "AuthorityKeyIdentifier";
// Private data members
private static final byte TAG_ID = 0;
private static final byte TAG_NAMES = 1;
private static final byte TAG_SERIAL_NUM = 2;
private KeyIdentifier id = null;
private GeneralNames names = null;
private SerialNumber serialNum = null;
// Encode only the extension value
private void encodeThis() {
if (id == null && names == null && serialNum == null) {
this.extensionValue = null;
return;
}
DerOutputStream seq = new DerOutputStream();
DerOutputStream tmp = new DerOutputStream();
if (id != null) {
DerOutputStream tmp1 = new DerOutputStream();
id.encode(tmp1);
tmp.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
false, TAG_ID), tmp1);
}
if (names != null) {
DerOutputStream tmp1 = new DerOutputStream();
names.encode(tmp1);
tmp.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
true, TAG_NAMES), tmp1);
}
if (serialNum != null) {
DerOutputStream tmp1 = new DerOutputStream();
serialNum.encode(tmp1);
tmp.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
false, TAG_SERIAL_NUM), tmp1);
}
seq.write(DerValue.tag_Sequence, tmp);
this.extensionValue = seq.toByteArray();
}
/**
* The default constructor for this extension. At least one parameter
* must be non null. Null parameters make the element optional (not present).
*
* @param kid the KeyIdentifier associated with this extension.
* @param names the GeneralNames associated with this extension
* @param sn the CertificateSerialNumber associated with
* this extension.
*/
public AuthorityKeyIdentifierExtension(KeyIdentifier kid, GeneralNames names,
SerialNumber sn) {
if (kid == null && names == null && sn == null) {
throw new IllegalArgumentException(
"AuthorityKeyIdentifierExtension cannot be empty");
}
this.id = kid;
this.names = names;
this.serialNum = sn;
this.extensionId = PKIXExtensions.AuthorityKey_Id;
this.critical = false;
encodeThis();
}
/**
* Create the extension from the passed DER encoded value of the same.
*
* @param critical true if the extension is to be treated as critical.
* @param value an array of DER encoded bytes of the actual value.
* @exception ClassCastException if value is not an array of bytes
* @exception IOException on error.
*/
public AuthorityKeyIdentifierExtension(Boolean critical, Object value)
throws IOException {
this.extensionId = PKIXExtensions.AuthorityKey_Id;
this.critical = critical.booleanValue();
this.extensionValue = (byte[]) value;
DerValue val = new DerValue(this.extensionValue);
if (val.tag != DerValue.tag_Sequence) {
throw new IOException("Invalid encoding for " +
"AuthorityKeyIdentifierExtension.");
}
// Note that all the fields in AuthorityKeyIdentifier are defined as
// being OPTIONAL, i.e., there could be an empty SEQUENCE, resulting
// in val.data being null.
while ((val.data != null) && (val.data.available() != 0)) {
DerValue opt = val.data.getDerValue();
// NB. this is always encoded with the IMPLICIT tag
// The checks only make sense if we assume implicit tagging,
// with explicit tagging the form is always constructed.
if (opt.isContextSpecific(TAG_ID) && !opt.isConstructed()) {
if (id != null)
throw new IOException("Duplicate KeyIdentifier in " +
"AuthorityKeyIdentifier.");
opt.resetTag(DerValue.tag_OctetString);
id = new KeyIdentifier(opt);
} else if (opt.isContextSpecific(TAG_NAMES) &&
opt.isConstructed()) {
if (names != null)
throw new IOException("Duplicate GeneralNames in " +
"AuthorityKeyIdentifier.");
opt.resetTag(DerValue.tag_Sequence);
names = new GeneralNames(opt);
} else if (opt.isContextSpecific(TAG_SERIAL_NUM) &&
!opt.isConstructed()) {
if (serialNum != null)
throw new IOException("Duplicate SerialNumber in " +
"AuthorityKeyIdentifier.");
opt.resetTag(DerValue.tag_Integer);
serialNum = new SerialNumber(opt);
} else
throw new IOException("Invalid encoding of " +
"AuthorityKeyIdentifierExtension.");
}
}
/**
* Return the object as a string.
*/
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append(super.toString())
.append("AuthorityKeyIdentifier [\n");
if (id != null) {
sb.append(id); // id already has a newline
}
if (names != null) {
sb.append(names).append('\n');
}
if (serialNum != null) {
sb.append(serialNum).append('\n');
}
sb.append("]\n");
return sb.toString();
}
/**
* Write the extension to the OutputStream.
*
* @param out the DerOutputStream to write the extension to.
*/
@Override
public void encode(DerOutputStream out) {
if (this.extensionValue == null) {
extensionId = PKIXExtensions.AuthorityKey_Id;
critical = false;
encodeThis();
}
super.encode(out);
}
public KeyIdentifier getKeyIdentifier() {
return id;
}
public GeneralNames getAuthName() {
return names;
}
public SerialNumber getSerialNumber() {
return serialNum;
}
/**
* Return the name of this extension.
*/
@Override
public String getName() {
return NAME;
}
/**
* Return the encoded key identifier, or null if not specified.
*/
public byte[] getEncodedKeyIdentifier() throws IOException {
if (id != null) {
DerOutputStream derOut = new DerOutputStream();
id.encode(derOut);
return derOut.toByteArray();
}
return null;
}
}