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Class KEM.Encapsulator

java.lang.Object

javax.crypto.KEM.Encapsulator

Enclosing class:: KEM

public static final class KEM.Encapsulator extends Object

An encapsulator, generated by KEM.newEncapsulator(java.security.PublicKey) on the KEM sender side.

This class represents the key encapsulation function of a KEM. Each invocation of the encapsulate method generates a new secret key and key encapsulation message that is returned in an KEM.Encapsulated object.

Since:: 21

Method Summary

Modifier and Type	Method	Description
`KEM.Encapsulated`	`encapsulate()`	The key encapsulation function.
`KEM.Encapsulated`	`encapsulate(int from, int to, String algorithm)`	The key encapsulation function.
`int`	`encapsulationSize()`	Returns the size of the key encapsulation message.
`String`	`providerName()`	Returns the name of the provider.
`int`	`secretSize()`	Returns the size of the shared secret.

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

providerName

public String providerName()

Returns the name of the provider.

Returns:: the name of the provider

encapsulate

public KEM.Encapsulated encapsulate()

The key encapsulation function.

This method is equivalent to encapsulate(0, secretSize(), "Generic"). This combination of arguments must be supported by every implementation.

The generated secret key is usually passed to a key derivation function (KDF) as the input keying material.

Returns:: a KEM.Encapsulated object containing the shared secret, key encapsulation message, and optional parameters. The shared secret is a SecretKey containing all of the bytes of the secret, and an algorithm name of "Generic".

encapsulate

public KEM.Encapsulated encapsulate(int from, int to, String algorithm)

The key encapsulation function.

Each invocation of this method generates a new secret key and key encapsulation message that is returned in an KEM.Encapsulated object.

An implementation may choose to not support arbitrary combinations of from, to, and algorithm.

Parameters:: from - the initial index of the shared secret byte array to be returned, inclusive; to - the final index of the shared secret byte array to be returned, exclusive; algorithm - the algorithm name for the secret key that is returned
Returns:: a KEM.Encapsulated object containing a portion of the shared secret, key encapsulation message, and optional parameters. The portion of the shared secret is a SecretKey containing the bytes of the secret ranging from from to to, exclusive, and an algorithm name as specified. For example, encapsulate(0, 16, "AES") uses the first 16 bytes of the shared secret as a 128-bit AES key.
Throws:: IndexOutOfBoundsException - if from < 0, from > to, or to > secretSize(); NullPointerException - if algorithm is null; UnsupportedOperationException - if the combination of from, to, and algorithm is not supported by the encapsulator

secretSize

public int secretSize()

Returns the size of the shared secret.

This method can be called to find out the length of the shared secret before encapsulate is called or if the obtained SecretKey is not extractable.

Returns:: the size of the shared secret

encapsulationSize

public int encapsulationSize()

Returns the size of the key encapsulation message.

This method can be called to find out the length of the encapsulation message before encapsulate is called.

Returns:: the size of the key encapsulation message

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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/javax/crypto/KEM.Encapsulator.html