org.bouncycastle.pqc.crypto.ntruplus

Class NTRUPlusKEMExtractor

java.lang.Object

org.bouncycastle.pqc.crypto.ntruplus.NTRUPlusKEMExtractor

All Implemented Interfaces:

EncapsulatedSecretExtractor

public class NTRUPlusKEMExtractor
extends java.lang.Object
implements EncapsulatedSecretExtractor

NTRU+ decapsulation.

Not thread safe. The NTRUPlusEngine built here keeps one SHAKE instance in a field, so two threads sharing an extractor interleave its absorb and squeeze phases: the secrets they recover do not match the sender's, and an IllegalStateException from the digest is also possible. Give each thread its own extractor - construction is cheap, roughly a thousandth of a decapsulation. The KEM.Decapsulator that javax.crypto.KEM builds does exactly that, since that API requires decapsulate to be safe for concurrent use.

Constructor Summary

Constructors

Constructor and Description
NTRUPlusKEMExtractor(NTRUPlusPrivateKeyParameters privateKey)

Method Summary

Modifier and Type	Method and Description
byte[]	extractSecret(byte[] encapsulation) Extract the shared secret from an NTRU+ encapsulation.
int	getEncapsulationLength() Return the length in bytes of the encapsulation.

Methods inherited from class java.lang.Object

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

Constructor Detail

NTRUPlusKEMExtractor

public NTRUPlusKEMExtractor(NTRUPlusPrivateKeyParameters privateKey)

Method Detail

extractSecret

public byte[] extractSecret(byte[] encapsulation)

Extract the shared secret from an NTRU+ encapsulation.

NTRU+ rejects an invalid encapsulation explicitly rather than implicitly: there is no pseudorandom rejection secret, so an encapsulation that fails the re-encryption check, or is not a canonical encoding, is refused with an exception instead of yielding a secret.

Specified by:

extractSecret in interface EncapsulatedSecretExtractor

Parameters:

encapsulation - the encapsulated secret.

Returns:

the shared secret.

Throws:

java.lang.IllegalArgumentException - if the encapsulation is the wrong length or is rejected.

getEncapsulationLength

public int getEncapsulationLength()

Description copied from interface: EncapsulatedSecretExtractor

Return the length in bytes of the encapsulation.

Specified by:

getEncapsulationLength in interface EncapsulatedSecretExtractor

Returns:

length in bytes of an encapsulation for this parameter set.