pkenc_elgamal85

ElGamal Public Key Encryption Scheme (ElGamal85)

Authors: T. ElGamal

Title: “A Public Key Cryptosystem and a Signature Scheme Based on Discrete Logarithms”

Published in: CRYPTO 1984

Available from: http://en.wikipedia.org/wiki/ElGamal_encryption

Notes:

Scheme Properties

• Type: encryption (public key)

• Setting: DDH-hard prime order group

• Assumption: DDH

Implementation

Authors:

10. Ayo Akinyele

Date:

3/2011

class pkenc_elgamal85.ElGamal(groupObj, p=0, q=0)

Bases: PKEnc

>>> from charm.toolbox.eccurve import prime192v2
>>> from charm.toolbox.ecgroup import ECGroup
>>> groupObj = ECGroup(prime192v2)
>>> el = ElGamal(groupObj)    
>>> (public_key, secret_key) = el.keygen()
>>> msg = b"hello world!12345678"
>>> cipher_text = el.encrypt(public_key, msg)
>>> decrypted_msg = el.decrypt(public_key, secret_key, cipher_text)    
>>> decrypted_msg == msg
True
>>> from charm.toolbox.integergroup import IntegerGroupQ, integer
>>> p = integer(148829018183496626261556856344710600327516732500226144177322012998064772051982752493460332138204351040296264880017943408846937646702376203733370973197019636813306480144595809796154634625021213611577190781215296823124523899584781302512549499802030946698512327294159881907114777803654670044046376468983244647367)
>>> q = integer(74414509091748313130778428172355300163758366250113072088661006499032386025991376246730166069102175520148132440008971704423468823351188101866685486598509818406653240072297904898077317312510606805788595390607648411562261949792390651256274749901015473349256163647079940953557388901827335022023188234491622323683)
>>> groupObj = IntegerGroupQ()
>>> el = ElGamal(groupObj, p, q)    
>>> (public_key, secret_key) = el.keygen()
>>> msg = b"hello world!"
>>> cipher_text = el.encrypt(public_key, msg)
>>> decrypted_msg = el.decrypt(public_key, secret_key, cipher_text)    
>>> decrypted_msg == msg
True

decrypt(pk, sk, c)

encrypt(pk, M)

keygen(secparam=1024)

class pkenc_elgamal85.ElGamalCipher(ct)

Bases: dict