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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.

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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/security/cert/Extension.html