test.java

import java.util.Base64;
import org.bouncycastle.asn1.util.*;
import org.bouncycastle.asn1.*;

class Test {
  static DERSequence makeSalt(int type, String salt) throws Exception {
    return new DERSequence(new ASN1Encodable[]{
        new DERTaggedObject(true, 0, new DERInteger(type)),
        new DERTaggedObject(true, 1, new DEROctetString(salt.getBytes("UTF-8")))
      });
  }
  
  static DERSequence makeEncryptionKey(int enctype, byte[] value) {
    return new DERSequence(new ASN1Encodable[]{
        new DERTaggedObject(true, 0, new DERInteger(enctype)),
        new DERTaggedObject(true, 1, new DEROctetString(value))
      });
  }
  
  static DERSequence makeKrbKey(DERSequence salt, DERSequence key) {
    return new DERSequence(new ASN1Encodable[]{
      new DERTaggedObject(true, 0, salt),
      new DERTaggedObject(true, 1, key)
    });
  }
  
  public static void main(String[] args) throws Exception {  
    DERSequence krbKeys = new DERSequence(new ASN1Encodable[]{
        makeKrbKey(makeSalt(4, "foo"), makeEncryptionKey(17, new byte[16])),
        makeKrbKey(makeSalt(4, "foo"), makeEncryptionKey(18, new byte[32]))
      });;
    
    DERSequence krbKeySet = new DERSequence(new ASN1Encodable[]{
        new DERTaggedObject(true, 0, new DERInteger(1)),
        new DERTaggedObject(true, 1, new DERInteger(1)),
        new DERTaggedObject(true, 2, new DERInteger(1)),
        new DERTaggedObject(true, 3, new DERInteger(1)),
        new DERTaggedObject(true, 4, krbKeys)
      });

    System.out.println(Base64.getEncoder().encodeToString(krbKeySet.getEncoded()));
  }
}