| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291 | /* * Copyright 2018 Scytl Secure Electronic Voting SA * * All rights reserved * * See our extended copyright notice in *file 'Copyright.txt' which is part of this source code package *//* jshint node:true */'use strict';var ZeroKnowledgeProofProver = require('../prover');var ZeroKnowledgeProofVerifier = require('../verifier');var ZeroKnowledgeProof = require('../proof');var ZeroKnowledgeProofPreComputation = require('../pre-computation');var PhiFunction = require('../phi-function');var ProgressMeter = require('../progress-meter');var validator = require('../input-validator');module.exports = SchnorrProofHandler;/** * @class SchnorrProofHandler * @classdesc Encapsulates a handler for the Schnorr zero-knowledge proof of *            knowledge generation, pre-computation and verification processes. *            To instantiate this object, use the method {@link *            ZeroKnowledgeProofService.newSchnorrProofHandler}. * @param {ZpSubgroup} *            group The Zp subgroup to which all exponents and Zp group elements *            required for the proof generation are associated or belong, *            respectively. * @param {MessageDigestService} *            messageDigestService The message digest service. * @param {MathematicalService} *            mathematicalService The mathematical service. */function SchnorrProofHandler(group, messageDigestService, mathematicalService) {  var NUM_PHI_INPUTS = 1;  var NUM_PHI_OUTPUTS = 1;  var COMPUTATION_RULES = [[[1, 1]]];  var DEFAULT_AUXILIARY_DATA = 'SchnorrProof';  var VOTER_ID_PREFIX = 'SchnorrProof:VoterID=';  var ELECTION_ID_PREFIX = 'ElectionEventID=';  var prover_ =      new ZeroKnowledgeProofProver(messageDigestService, mathematicalService);  var verifier_ =      new ZeroKnowledgeProofVerifier(messageDigestService, mathematicalService);  var progressCallback_;  var progressPercentMinCheckInterval_;  var measureProgress_ = false;  /**   * Generates a Schnorr zero-knowledge proof of knowledge.   *   * @function generate   * @memberof SchnorrProofHandler   * @param {Exponent}   *            secret The secret exponent used to generate the gamma element,   *            the knowledge of which must be proven   * @param {ZpGroupElement}   *            gamma The Zp subgroup generator exponentiated to the secret   *            exponent.   * @param {Object}   *            [options] An object containing optional arguments.   * @param {Uint8Array|string}   *            [options.data=''] Auxiliary data.   * @param {ZeroKnowledgeProofPreComputation}   *            [options.preComputation=Generated internally] A   *            pre-computation of the Schnorr zero-knowledge proof of   *            knowledge.   * @param {string}   *            [options.voterId] The voter ID. If this value is set then the   *            <code>electionId</code> option must also be set. In this   *            case, the <code>data</code> parameter will be ignored.   * @param {string}   *            [options.electionId] The election ID. If this value is set   *            then the <code>voterId</code> option must also be set. In   *            this case, the <code>data</code> parameter will be ignored.   * @returns {ZeroKnowledgeProof} The Schnorr zero-knowledge proof of   *          knowledge.   * @throws {Error}   *             If the input data validation fails.   */  this.generate = function(secret, gamma, options) {    options = options || {};    checkGenerationData(secret, gamma, options);    var data = options.data;    if (typeof data === 'undefined') {      data = DEFAULT_AUXILIARY_DATA;    }    var voterId = options.voterId;    var electionId = options.electionId;    if (voterId && electionId) {      data = VOTER_ID_PREFIX + voterId + ELECTION_ID_PREFIX + electionId;    }    var preComputation = options.preComputation;    var privateValues = [secret];    var publicValues = [gamma];    if (typeof preComputation === 'undefined') {      preComputation = this.preCompute();    }    return prover_.prove(        group, privateValues, publicValues, data, preComputation);  };  /**   * Pre-computes a Schnorr zero-knowledge proof of knowledge. IMPORTANT: The   * same pre-computed values must not be used twice.   *   * @function preCompute   * @memberof SchnorrProofHandler   * @returns {ZeroKnowledgeProofPreComputation} The Schnorr zero-knowledge   *          proof of knowledge pre-computation.   */  this.preCompute = function() {    var phiFunction = newPhiFunction(group);    if (!measureProgress_) {      return prover_.preCompute(group, phiFunction);    } else {      var preComputation =          prover_.preCompute(group, phiFunction, newProgressMeter());      measureProgress_ = false;      return preComputation;    }  };  /**   * Verifies a Schnorr zero-knowledge proof of knowledge.   *   * @function verify   * @memberof SchnorrProofHandler   * @param {ZeroKnowledgeProof}   *            proof The Schnorr zero-knowledge proof of knowledge to verify.   * @param {ZpGroupElement}   *            gamma The Zp subgroup generator exponentiated to the secret   *            exponent, the knowledge of which must be verified.   * @param {Object}   *            [options] An object containing optional arguments.   * @param {Uint8Array|string}   *            [options.data=''] Auxiliary data. It must be the same as that   *            used to generate the proof.   * @returns {boolean} <code>true</code> if the Schnorr zero-knowledge   *          proof of knowledge was verified, <code>false</code> otherwise.   * @throws {Error}   *             If the input data validation fails.   */  this.verify = function(proof, gamma, options) {    options = options || {};    checkVerificationData(proof, gamma, options);    var data = options.data;    if (typeof data === 'undefined') {      data = DEFAULT_AUXILIARY_DATA;    }    var voterId = options.voterId;    var electionId = options.electionId;    if (voterId && electionId) {      data = VOTER_ID_PREFIX + voterId + ELECTION_ID_PREFIX + electionId;    }    var phiFunction = newPhiFunction(group);    var publicValues = [gamma];    if (!measureProgress_) {      return verifier_.verify(group, proof, phiFunction, publicValues, data);    } else {      var verified = verifier_.verify(          group, proof, phiFunction, publicValues, data, newProgressMeter());      measureProgress_ = false;      return verified;    }  };  /**   * Indicates that a progress meter is to be used for the next Schnorr   * zero-knowledge proof of knowledge operation to be performed.   *   * @function measureProgress   * @memberof SchnorrProofHandler   * @param {function}   *            callback The callback function for the progress meter.   * @param {Object}   *            [options] An object containing optional arguments.   * @param {number}   *            [minCheckInterval=10] The minimum interval used to check   *            progress, as a percentage of the expected final progress   *            value..   * @returns {SchnorrProofHandler} A reference to this object, to facilitate   *          method chaining.   * @throws {Error}   *             If the input data validation fails.   */  this.measureProgress = function(callback, minCheckInterval) {    validator.checkProgressMeterData(        callback, minCheckInterval, 'Schnorr zero-knowledge proof');    progressCallback_ = callback;    progressPercentMinCheckInterval_ = minCheckInterval;    measureProgress_ = true;    return this;  };  function newPhiFunction(group) {    var baseElements = [group.generator];    return new PhiFunction(        NUM_PHI_INPUTS, NUM_PHI_OUTPUTS, COMPUTATION_RULES, baseElements);  }  function newProgressMeter() {    return new ProgressMeter(        NUM_PHI_OUTPUTS, progressCallback_, progressPercentMinCheckInterval_);  }  function checkGenerationData(secret, gamma, options) {    validator.checkExponent(        secret, 'Secret exponent for Schnorr proof generation', group.q);    validator.checkZpGroupElement(        gamma, 'ElGamal gamma Zp group element for Schnorr proof generation',        group);    if (typeof options.data !== 'undefined' &&        typeof options.data !== 'string') {        validator.checkIsInstanceOf(            options.data, Uint8Array, 'Uint8Array',            'Non-string auxiliary data for Schnorr proof generation');    }    if (typeof options.voterId !== 'undefined') {      validator.checkIsNonEmptyString(          options.voterId, 'Voter ID for Schnorr proof generation');      if (typeof options.electionId === 'undefined') {        throw new Error(            'Voter ID was provided but no election ID was provided for Schnorr proof generation');      }    }    if (typeof options.electionId !== 'undefined') {      validator.checkIsNonEmptyString(          options.electionId, 'Election ID for Schnorr proof generation');      if (typeof options.voterId === 'undefined') {        throw new Error(            'Election ID was provided but no voter ID was provided for Schnorr proof generation');      }    }    if (typeof options.preComputation !== 'undefined') {      validator.checkIsInstanceOf(          options.preComputation, ZeroKnowledgeProofPreComputation,          'ZeroKnowledgeProofPreComputation',          'Pre-computation for Schnorr proof generation');    }  }  function checkVerificationData(proof, gamma, options) {    validator.checkIsInstanceOf(        proof, ZeroKnowledgeProof, 'ZeroKnowledgeProof',        'Schnorr zero-knowledge proof');    validator.checkZpGroupElement(        gamma, 'ElGamal gamma Zp group element for Schnorr proof verification',        group);    if (typeof options.data !== 'undefined' &&        typeof options.data !== 'string') {        validator.checkIsInstanceOf(            options.data, Uint8Array, 'Uint8Array',            'Non-string auxiliary data for Schnorr proof verification');    }    if (typeof options.voterId !== 'undefined') {      validator.checkIsNonEmptyString(          options.voterId, 'Voter ID for Schnorr proof verification');      if (typeof options.electionId === 'undefined') {        throw new Error(            'Voter ID was provided but no election ID was provided for Schnorr proof verification');      }    }    if (typeof options.electionId !== 'undefined') {      validator.checkIsNonEmptyString(          options.electionId, 'Election ID for Schnorr proof verification');      if (typeof options.voterId === 'undefined') {        throw new Error(            'Election ID was provided but no voter ID was provided for Schnorr proof verification');      }    }  }}
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