Java tutorial
package org.bouncycastle.asn1; import java.io.IOException; /** * DER TaggedObject - in ASN.1 notation this is any object preceded by * a [n] where n is some number - these are assumed to follow the construction * rules (as with sequences). */ public class DERTaggedObject extends ASN1TaggedObject { /** * @param explicit true if an explicitly tagged object. * @param tagNo the tag number for this object. * @param obj the tagged object. */ public DERTaggedObject(boolean explicit, int tagNo, ASN1Encodable obj) { super(explicit, tagNo, obj); } public DERTaggedObject(int tagNo, ASN1Encodable encodable) { super(true, tagNo, encodable); } boolean isConstructed() { return explicit || obj.toASN1Primitive().toDERObject().isConstructed(); } int encodedLength() throws IOException { ASN1Primitive primitive = obj.toASN1Primitive().toDERObject(); int length = primitive.encodedLength(); if (explicit) { return StreamUtil.calculateTagLength(tagNo) + StreamUtil.calculateBodyLength(length) + length; } else { // header length already in calculation length = length - 1; return StreamUtil.calculateTagLength(tagNo) + length; } } void encode(ASN1OutputStream out, boolean withTag) throws IOException { ASN1Primitive primitive = obj.toASN1Primitive().toDERObject(); int flags = BERTags.TAGGED; if (explicit || primitive.isConstructed()) { flags |= BERTags.CONSTRUCTED; } out.writeTag(withTag, flags, tagNo); if (explicit) { out.writeLength(primitive.encodedLength()); } primitive.encode(out.getDERSubStream(), explicit); } ASN1Primitive toDERObject() { return this; } ASN1Primitive toDLObject() { return this; } }