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()	Creates and returns a copy of this object.
boolean	equals(Object obj)	Indicates whether some other object is "equal to" this one.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
final Class<?>	getClass()	Returns the runtime class of this Object.
int	hashCode()	Returns a hash code value for this object.
final void	notify()	Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll()	Wakes up all threads that are waiting on this object's monitor.
String	toString()	Returns a string representation of the object.
final void	wait()	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
final void	wait(long timeoutMillis)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
final void	wait(long timeoutMillis, int nanos)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

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 {code 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