DataVerifier

The DataVerifier circuit is a zkSNARKs circuit is responsible for verifying certain constraints over the provided data and returning hash values for further usage.

Template Parameters

The circuit is defined with two parameters:

• tLevel: Total number of data entries.

• nLevel: Number of data entries with constraints.

template DataVerifier (tLevel, nLevel) { /*...*/ }

Input Signals

The circuit takes in the following input signals:

• data: An array of tLevel + nLevel size, which contains the data entries that the circuit will process.

• code: An array of tLevel + nLevel size, which serves as a form of mask for the data.

• constraint_upper: An array of nLevel size, which specifies the upper bound for the respective data entry.

• constraint_lower: An array of nLevel size, which specifies the lower bound for the respective data entry.

signal input data[tLevel + nLevel];
signal input code[tLevel + nLevel];
signal input constraint_upper[nLevel];
signal input constraint_lower[nLevel];

Output Signals

The circuit produces two output signals:

• idHash: A 2-element array which holds the hash of the data input signal.

• constraintHash: A 2-element array which holds the hash of the data entries with constraints.

signal output idHash[2];
signal output constraintHash[2];

Components

• comp_upper: An array of GreaterEqThan components of nLevel size that checks if each constrained data entry is greater or equal to its respective upper constraint.

• comp_lower: An array of LessEqThan components of nLevel size that checks if each constrained data entry is less or equal to its respective lower constraint.

• hasher: A Pedersen hashing component that hashes the data input signal.

• chasher: A Pedersen hashing component that hashes the data entries with constraints.

component comp_upper[nLevel];
component comp_lower[nLevel];
component hasher = Pedersen(tLevel + nLevel);
component chasher = Pedersen(tLevel);

Inclusion of External Circuits

The circuit makes use of the comparators and pedersen circuits from the circomlib library.

include "../../node_modules/circomlib/circuits/comparators.circom";
include "../../node_modules/circomlib/circuits/pedersen.circom";

BitSize Variable

A variable bitSize is declared and initialized with 36. This bitSize is the maximum bit length of data the GreaterEqThan and LessEqThan components can handle.

// max size = 68,719,476,735 (68.7b)
var bitSize = 36;