proofs::ProofOfCorrectDecryption Class Reference

Performs a proof of shuffle of commitments. It is an implementation of the Verfication class. More...

#include <proofofcorrectdecryption.hpp>

Inheritance diagram for proofs::ProofOfCorrectDecryption:

Collaboration diagram for proofs::ProofOfCorrectDecryption:

Public Member Functions
	ProofOfCorrectDecryption (bool &readingWasOK, XmlConfig *config, std::vector< uint8_t > prefix, unsigned int N, arithm::Elmt partialJointKey, elGamal::CipherGroup cipherTextsGrp, arithm::Group *plainTextGrp, elGamal::ArrayOfCiphers inputCiphers, arithm::ArrayOfElmts decryptionFactors, verifierUtils::ByteTree *commitmentFSproof, verifierUtils::ByteTree *replyFSproof)
	Creates an instance of the ProofOfCorrectDecryption class by setting its attributes.
bool	isEverythingOK ()
	Checks that the joint decryption of the re-encrypted and permuted vote went as expected.
Public Member Functions inherited from proofs::Verification
	Verification (XmlConfig *config, std::vector< uint8_t > prefix, unsigned int nZero)
	Creates an instance of a Verification class by setting its two attributes.
arithm::ArrayOfElmts	randomExponents (verifierUtils::ByteTree *bts, std::vector< uint8_t > &s)
	Used to compute a random exponents vector according to the specification.
arithm::Elmt	getChallenge (std::vector< uint8_t > s)
	Returns a challenge computed from the original seed s and a bytetree.
arithm::ArrayOfElmts	getGenerators ()
	Returns the h attribute.

Private Attributes
arithm::Elmt	y
	The partial public key .
elGamal::CipherGroup	C
	The ciphertexts group .
arithm::Group *	M
	The plaintexts group .
elGamal::ArrayOfCiphers	w
	The array of input ciphertexts in .
arithm::ArrayOfElmts	f
	Array of decryption factors in .

Additional Inherited Members
Protected Attributes inherited from proofs::Verification
XmlConfig *	protocolFile
	A class containing the information in the protocol info file.
cryptoTools::SHAx *	H
	The hashfunction to be used by the random oracles.
cryptoTools::RO *	ROs
	The random oracle to use to seed the PRG.
cryptoTools::RO *	ROv
	The random oracle to use to generate challenges.
std::vector< uint8_t >	rho
	, a prefix for the random oracle.
unsigned int	n0
	(or ), the size of the arrays.
unsigned int	ne
	, number of bits in each component of random vectors used for batching.
unsigned int	nr
	, acceptable "statistical error" when deriving independent generators.
unsigned int	nv
	, number of bits in challenges.
cryptoTools::PRG *	prg
	Pseudo-random generator used to derive random vectors for batching.
arithm::Group *	gq
	a group of prime order with characteristic .
arithm::Field *	zq
	The field in which the exponent live, .
arithm::ArrayOfElmts	h
	An array of independant generators .
verifierUtils::ByteTree *	tau
	The commitment of the Fiat-Shamir proof, .
verifierUtils::ByteTree *	sigma
	The reply of the Fiat-Shamir proof, .

Detailed Description

Performs a proof of shuffle of commitments. It is an implementation of the Verfication class.

The operation performed in this class are just implementation of the verificatum verifier specification, namely page 17.

Definition at line 30 of file proofofcorrectdecryption.hpp.

Constructor & Destructor Documentation

ProofOfCorrectDecryption::ProofOfCorrectDecryption	(	bool &	readingWasOK,
		XmlConfig *	config,
		std::vector< uint8_t >	prefix,
		unsigned int	N,
		arithm::Elmt	partialJointKey,
		elGamal::CipherGroup	cipherTextsGrp,
		arithm::Group *	plainTextGrp,
		elGamal::ArrayOfCiphers	inputCiphers,
		arithm::ArrayOfElmts	decryptionFactors,
		verifierUtils::ByteTree *	commitmentFSproof,
		verifierUtils::ByteTree *	replyFSproof
	)

Creates an instance of the ProofOfCorrectDecryption class by setting its attributes.

If any variable is wrong, readingWasOK takes the value false. Otherwise, this variable is equal to true at the end of the construction.

Parameters

[out]	readingWasOK	Is false at the end of the construction if there was a problem.
	config	The protocol info file to use.
	prefix	The value to give to the rho attribute.
	N	The actual number of ciphers.
	partialJointKey	The partial joint El Gamal public key.
	cipherTextsGrp	The field in which live ciphertexts.
	plainTextGrp	The field in which live plaintexts.
	inputCiphers	The ciphers to check.
	decryptionFactors	The decryption factors.
	commitmentFSproof	Commitments of the Fiat-Shamir proof.
	replyFSproof	Reply of the Fiat-Shamir proof.

Returns

Definition at line 21 of file proofofcorrectdecryption.cpp.

        :
        Verification(config,prefix,N),
        y(partialJointKey),
        C(cipherTextsGrp),
        M(plainTextGrp),
        w(inputCiphers),
        f(decryptionFactors)
{
        readingWasOK = true;

        // checking arrays' sizes
        if (w.size() != n0)
        {
                std::cout<<"ERROR: in ProofOfCorrectDecryption:"
                         <<"number of input ciphers does not match N:"
                         <<"\nN="<<n0
                         <<"\nw->getSize()="<<w.size()<<std::endl;
                readingWasOK = false;
        }
        if (f.size() != n0)
        {
                std::cout<<"ERROR: in ProofOfCorrectDecryption:"
                         <<"number of decryption factors does not match N:"
                         <<"\nN="<<n0
                         <<"\nf->getSize()="<<f.size()<<std::endl;
                readingWasOK = false;
        }

        // Assigning bytetrees
        tau = commitmentFSproof;
        if ((tau->size()<2) || (!tau->isNode())
            || (!tau->getChild(0)->isLeaf())
            || (!tau->getChild(1)->isNode())
            || (!tau->getChild(1)->getChild(0)->isLeaf())
                )
        {
                std::cout<<"ERROR: in ProofOfCorrectDecryption:"
                         <<"tau is not valid.\ntau="
                         <<tau->toString()<<std::endl;
                readingWasOK = false;
        }
        sigma = replyFSproof;
        if (!sigma->isLeaf())
        {
                std::cout<<"ERROR: in ProofOfCorrectDecryption:"
                         <<"sigma is not valid.\nsigma="
                         <<sigma->toString()<<std::endl;
                readingWasOK = false;
        }