Module java.base
Package java.security.cert

Interface Extension

public interface Extension
This interface represents an X.509 extension.

Extensions provide a means of associating additional attributes with users or public keys and for managing a certification hierarchy. The extension format also allows communities to define private extensions to carry information unique to those communities.

Each extension contains an object identifier, a criticality setting indicating whether it is a critical or a non-critical extension, and an ASN.1 DER-encoded value. Its ASN.1 definition is: 


     Extension ::= SEQUENCE {
         extnId        OBJECT IDENTIFIER,
         critical      BOOLEAN DEFAULT FALSE,
         extnValue     OCTET STRING
                 -- contains a DER encoding of a value
                 -- of the type registered for use with
                 -- the extnId object identifier value
     }

This interface is designed to provide access to a single extension, unlike X509Extension which is more suitable for accessing a set of extensions.

Since:
1.7

  • Method Summary

    Modifier and Type Method Description
    void encode​(OutputStream out)
    Generates the extension's DER encoding and writes it to the output stream.
    String getId()
    Gets the extensions's object identifier.
    byte[] getValue()
    Gets the extensions's DER-encoded value.
    boolean isCritical()
    Gets the extension's criticality setting.

  • Method Details

    • getId

      String getId()
      Gets the extensions's object identifier.
      Returns:
      the object identifier as a String

    • isCritical

      boolean isCritical()
      Gets the extension's criticality setting.
      Returns:
      true if this is a critical extension.

    • getValue

      byte[] getValue()
      Gets the extensions's DER-encoded value. Note, this is the bytes that are encoded as an OCTET STRING. It does not include the OCTET STRING tag and length.
      Returns:
      a copy of the extension's value, or null if no extension value is present.

    • encode

      void encode​(OutputStream out) throws IOException
      Generates the extension's DER encoding and writes it to the output stream.
      Parameters:
      out - the output stream
      Throws:
      IOException - on encoding or output error.
      NullPointerException - if out is null.