org.cryptimeleon.craco.kem

Class AbstractHybridConstructionKEM

java.lang.Object

org.cryptimeleon.craco.kem.AbstractHybridConstructionKEM

All Implemented Interfaces:

KeyEncapsulationMechanism<SymmetricKey>, org.cryptimeleon.math.serialization.annotations.RepresentationRestorer, org.cryptimeleon.math.serialization.Representable, org.cryptimeleon.math.serialization.StandaloneRepresentable

public abstract class AbstractHybridConstructionKEM
extends java.lang.Object
implements KeyEncapsulationMechanism<SymmetricKey>

A KEM that implements encaps(EncryptionKey) by generating a random key and encrypting it afterwards with some encryption scheme.

Implementations of this abstract class need to define how to generate random plaintexts for the encryption scheme and how to derive a secret key (for a symmetric scheme) from the random plaintext (key derivation function).

Nested Class Summary

Nested classes/interfaces inherited from interface org.cryptimeleon.craco.kem.KeyEncapsulationMechanism

KeyEncapsulationMechanism.KeyAndCiphertext<T>

Field Summary

Fields

Modifier and Type	Field and Description
protected KeyDerivationFunction<? extends SymmetricKey>	kdf
protected EncryptionScheme	scheme

Constructor Summary

Constructors

Constructor and Description
AbstractHybridConstructionKEM(EncryptionScheme scheme, KeyDerivationFunction<? extends SymmetricKey> kdf)

Method Summary

Modifier and Type	Method and Description
SymmetricKey	decaps(CipherText encapsulatedKey, DecryptionKey sk) Takes an encapsulated key that was created by encaps() and decrypts it with sk.
KeyEncapsulationMechanism.KeyAndCiphertext<SymmetricKey>	encaps(EncryptionKey pk) Randomly chooses a key k and encrypts it using the given pk.
protected abstract PlainText	generateRandomPlaintext() Generates random plaintexts for the underlying scheme.
protected abstract int	getPlaintextMinEntropyInBit() Returns the min entropy, of generateRandomPlaintext i.e.
DecryptionKey	restoreDecapsulationKey(org.cryptimeleon.math.serialization.Representation repr)
CipherText	restoreEncapsulatedKey(org.cryptimeleon.math.serialization.Representation repr)
EncryptionKey	restoreEncapsulationKey(org.cryptimeleon.math.serialization.Representation repr)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.cryptimeleon.craco.kem.KeyEncapsulationMechanism

restoreFromRepresentation

Methods inherited from interface org.cryptimeleon.math.serialization.Representable

getRepresentation

Field Detail

scheme

protected EncryptionScheme scheme

kdf

protected KeyDerivationFunction<? extends SymmetricKey> kdf

Constructor Detail

AbstractHybridConstructionKEM

public AbstractHybridConstructionKEM(EncryptionScheme scheme,
                                     KeyDerivationFunction<? extends SymmetricKey> kdf)

Method Detail

generateRandomPlaintext

protected abstract PlainText generateRandomPlaintext()

Generates random plaintexts for the underlying scheme.

getPlaintextMinEntropyInBit

protected abstract int getPlaintextMinEntropyInBit()

Returns the min entropy, of generateRandomPlaintext i.e. -log2( max{Pr[Plaintext = m]} ) (where the maximum is over all possible m). Rounded down to an integer.

(if you choose uniformly random among n plaintexts, it's just floor(log2(n)))

encaps

public KeyEncapsulationMechanism.KeyAndCiphertext<SymmetricKey> encaps(EncryptionKey pk)

Description copied from interface: KeyEncapsulationMechanism

Randomly chooses a key k and encrypts it using the given pk. The result is (key, encapsulatedKey).

Specified by:

encaps in interface KeyEncapsulationMechanism<SymmetricKey>

Parameters:

pk - public key used for encrypting k

decaps

public SymmetricKey decaps(CipherText encapsulatedKey,
                           DecryptionKey sk)

Description copied from interface: KeyEncapsulationMechanism

Takes an encapsulated key that was created by encaps() and decrypts it with sk. That is, if (key, encapsulatedKey) = encaps(pk), then decrypt(encapsulatedKey, sk) == key.

Specified by:

decaps in interface KeyEncapsulationMechanism<SymmetricKey>

restoreEncapsulatedKey

public CipherText restoreEncapsulatedKey(org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restoreEncapsulatedKey in interface KeyEncapsulationMechanism<SymmetricKey>

restoreEncapsulationKey

public EncryptionKey restoreEncapsulationKey(org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restoreEncapsulationKey in interface KeyEncapsulationMechanism<SymmetricKey>

restoreDecapsulationKey

public DecryptionKey restoreDecapsulationKey(org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restoreDecapsulationKey in interface KeyEncapsulationMechanism<SymmetricKey>