Class HKDFParameterSpec.Builder

java.lang.Object

javax.crypto.spec.HKDFParameterSpec.Builder

Enclosing interface:

HKDFParameterSpec

public static final class HKDFParameterSpec.Builder
extends Object

This Builder builds Extract and ExtractThenExpand objects.

The Builder is initialized via the ofExtract method of HKDFParameterSpec. As stated in the class description, addIKM and/or addSalt may be called as needed. Finally, an object is "built" by calling either extractOnly or thenExpand for Extract and ExtractThenExpand use-cases respectively. Note that the Builder is not thread-safe.

Since:

25

Method Summary

Modifier and Type	Method	Description
HKDFParameterSpec.Builder	addIKM(byte[] ikm)	Adds input keying material (IKM) to the builder.
HKDFParameterSpec.Builder	addIKM(SecretKey ikm)	Adds input keying material (IKM) to the builder.
HKDFParameterSpec.Builder	addSalt(byte[] salt)	Adds a salt to the builder.
HKDFParameterSpec.Builder	addSalt(SecretKey salt)	Adds a salt to the builder.
HKDFParameterSpec.Extract	extractOnly()	Builds an Extract object from the current state of the Builder.
HKDFParameterSpec.ExtractThenExpand	thenExpand(byte[] info, int length)	Builds an ExtractThenExpand object from the current state of the Builder.

Methods declared in class Object

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

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
String	toString()	Answers a string containing a concise, human-readable description of the receiver.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

Method Details

extractOnly

public HKDFParameterSpec.Extract extractOnly()

Builds an Extract object from the current state of the Builder.

Returns:

an immutable Extract object

thenExpand

public HKDFParameterSpec.ExtractThenExpand thenExpand(byte[] info,
 int length)

Builds an ExtractThenExpand object from the current state of the Builder.

Implementation Note:

HKDF implementations will enforce that the length is not greater than 255 * HMAC length. HKDF implementations will also enforce that a null info value is treated as zero-length byte array.

Parameters:

info - the optional context and application specific information (may be null); the byte array is cloned to prevent subsequent modification

length - the length of the output keying material (must be greater than 0)

Returns:

an immutable ExtractThenExpand object

Throws:

IllegalArgumentException - if length is not greater than 0

addIKM

public HKDFParameterSpec.Builder addIKM(SecretKey ikm)

Adds input keying material (IKM) to the builder.

Users may call addIKM multiple times when the input keying material value is to be assembled piece-meal or if part of the IKM is to be supplied by a hardware crypto device. The ikms() method of the Extract or ExtractThenExpand object that is subsequently built returns the assembled input keying material as a list of SecretKey objects.

Parameters:

ikm - the input keying material (IKM) value

Returns:

this builder

Throws:

NullPointerException - if the ikm argument is null

addIKM

public HKDFParameterSpec.Builder addIKM(byte[] ikm)

Adds input keying material (IKM) to the builder. Note that an ikm byte array of length zero will be discarded.

Users may call addIKM multiple times when the input keying material value is to be assembled piece-meal or if part of the IKM is to be supplied by a hardware crypto device. The ikms() method of the Extract or ExtractThenExpand object that is subsequently built returns the assembled input keying material as a list of SecretKey objects.

Parameters:

ikm - the input keying material (IKM) value; the ikm byte array will be converted to a SecretKeySpec, which means that the byte array will be cloned inside the SecretKeySpec constructor

Returns:

this builder

Throws:

NullPointerException - if the ikm argument is null

addSalt

public HKDFParameterSpec.Builder addSalt(SecretKey salt)

Adds a salt to the builder.

Users may call addSalt multiple times when the salt value is to be assembled piece-meal or if part of the salt is to be supplied by a hardware crypto device. The salts() method of the Extract or ExtractThenExpand object that is subsequently built returns the assembled salt as a list of SecretKey objects.

Parameters:

salt - the salt value

Returns:

this builder

Throws:

NullPointerException - if the salt is null

addSalt

public HKDFParameterSpec.Builder addSalt(byte[] salt)

Adds a salt to the builder. Note that a salt byte array of length zero will be discarded.

Users may call addSalt multiple times when the salt value is to be assembled piece-meal or if part of the salt is to be supplied by a hardware crypto device. The salts() method of the Extract or ExtractThenExpand object that is subsequently built returns the assembled salt as a list of SecretKey objects.

Parameters:

salt - the salt value; the salt byte array will be converted to a SecretKeySpec, which means that the byte array will be cloned inside the SecretKeySpec constructor

Returns:

this builder

Throws:

NullPointerException - if the salt is null