/**
* Constructs an instance of Checksum from an ASN.1 encoded representation.
*
* @param encoding a single DER-encoded value.
* @exception Asn1Exception if an error occurs while decoding an ASN1 encoded data.
* @exception IOException if an I/O error occurs while reading encoded data.
*/
private Checksum(DerValue encoding) throws Asn1Exception, IOException {
DerValue der;
if (encoding.getTag() != DerValue.tag_Sequence) {
throw new Asn1Exception(Krb5.ASN1_BAD_ID);
}
der = encoding.getData().getDerValue();
if ((der.getTag() & (byte) 0x1F) == (byte) 0x00) {
cksumType = der.getData().getBigInteger().intValue();
} else throw new Asn1Exception(Krb5.ASN1_BAD_ID);
der = encoding.getData().getDerValue();
if ((der.getTag() & (byte) 0x1F) == (byte) 0x01) {
checksum = der.getData().getOctetString();
} else throw new Asn1Exception(Krb5.ASN1_BAD_ID);
if (encoding.getData().available() > 0) {
throw new Asn1Exception(Krb5.ASN1_BAD_ID);
}
}
/**
* Parse (unmarshal) a checksum object from a DER input stream. This form parsing might be used
* when expanding a value which is part of a constructed sequence and uses explicitly tagged type.
*
* @exception Asn1Exception if an error occurs while decoding an ASN1 encoded data.
* @exception IOException if an I/O error occurs while reading encoded data.
* @param data the Der input stream value, which contains one or more marshaled value.
* @param explicitTag tag number.
* @param optional indicates if this data field is optional
* @return an instance of Checksum.
*/
public static Checksum parse(DerInputStream data, byte explicitTag, boolean optional)
throws Asn1Exception, IOException {
if ((optional) && (((byte) data.peekByte() & (byte) 0x1F) != explicitTag)) {
return null;
}
DerValue der = data.getDerValue();
if (explicitTag != (der.getTag() & (byte) 0x1F)) {
throw new Asn1Exception(Krb5.ASN1_BAD_ID);
} else {
DerValue subDer = der.getData().getDerValue();
return new Checksum(subDer);
}
}