org.cryptimeleon.craco.kem

Interface KeyEncapsulationMechanism<T>

Type Parameters:

T - type of the encapsulated key

All Superinterfaces:

org.cryptimeleon.math.serialization.Representable, org.cryptimeleon.math.serialization.annotations.RepresentationRestorer, org.cryptimeleon.math.serialization.StandaloneRepresentable

All Known Subinterfaces:

AsymmetricKEM<T>

All Known Implementing Classes:

AbstractHybridConstructionKEM, ElgamalKEM, SymmetricKeyKEM

public interface KeyEncapsulationMechanism<T>
extends org.cryptimeleon.math.serialization.StandaloneRepresentable, org.cryptimeleon.math.serialization.annotations.RepresentationRestorer

A mechanism that is able to generate random symmetric keys and encrypt/decrypt them to build hybrid encryption schemes. For this purpose, encrypt and decrypt are called encaps and decaps, respectively.

The usual use case is:

1. call encaps(EncryptionKey) with the public key of the receiver to get a random symmetric key k and an encrypted version c
2. hand c to the receiver
3. the receiver calls decaps(CipherText, DecryptionKey) on c and their secret decryption key, which yields k
4. the receiver now has the same random key k as you

Cramer, Ronald, and Victor Shoup. Design and Analysis of Practical Public-Key Encryption Schemes Secure against Adaptive Chosen Ciphertext Attack. SIAM Journal on Computing 33, no. 1 (2003): 167-226. Page 201.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	KeyEncapsulationMechanism.KeyAndCiphertext<T>

Method Summary

Modifier and Type	Method and Description
T	decaps(CipherText encapsulatedKey, DecryptionKey sk) Takes an encapsulated key that was created by encaps() and decrypts it with sk.
KeyEncapsulationMechanism.KeyAndCiphertext<T>	encaps(EncryptionKey pk) Randomly chooses a key k and encrypts it using the given pk.
DecryptionKey	restoreDecapsulationKey(org.cryptimeleon.math.serialization.Representation repr)
CipherText	restoreEncapsulatedKey(org.cryptimeleon.math.serialization.Representation repr)
EncryptionKey	restoreEncapsulationKey(org.cryptimeleon.math.serialization.Representation repr)
default java.lang.Object	restoreFromRepresentation(java.lang.reflect.Type type, org.cryptimeleon.math.serialization.Representation repr)

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

getRepresentation

Method Detail

encaps

KeyEncapsulationMechanism.KeyAndCiphertext<T> encaps(EncryptionKey pk)

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

Parameters:

pk - public key used for encrypting k

decaps

T decaps(CipherText encapsulatedKey,
         DecryptionKey sk)
  throws java.lang.IllegalArgumentException

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.

Throws:

java.lang.IllegalArgumentException

restoreEncapsulatedKey

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

restoreEncapsulationKey

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

restoreDecapsulationKey

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

restoreFromRepresentation

default java.lang.Object restoreFromRepresentation(java.lang.reflect.Type type,
                                                   org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restoreFromRepresentation in interface org.cryptimeleon.math.serialization.annotations.RepresentationRestorer