Force 1 in the verifier

README

@@ -1,107 +0,0 @@
-# javascript implementation of zkSnark
-
-This is a javascript implementation of zkSnarks.
-
-This library allows to do the trusted setup,  generate proofs and verify the proofs.
-
-This library uses the compiled circuits generated by the jaz compiler.
-
-## Install
-
-```
-npm install zkSnark
-```
-
-## Usage
-
-### import
-
-```
-const zkSnark = require("zksnark");
-```
-
-### Load a circuit.
-
-```
-// "myCircuit.cir" is the output of the jaz compiler
-
-const circuitDef = JSON.parse(fs.readFileSync("myCircuit.cir", "utf8"));
-const circuit = new zkSnark.Circuit(circuitDef);
-```
-
-### Inspect the circuit.
-
-```
-    // `signalId` can always be a number or an alias string
-
-    circuit.m; // number of constrains
-    circuit.n; // number of signals
-    circuit.p; // number of public signals (nPublicInputs + nOutputs)
-
-    // The array of signals is always sorted in this order:
-    // [ outputs, publicInputs, privedInputs, internalSignals, constants]
-
-    // returns a,b and c coeficients of the `signalId` on a given `constrain`
-    circuit.a(constrain, signalId)
-    circuit.b(constrain, signalId)
-    circuit.c(constrain, signalId)
-
-    circuit.nOutputs           // number of public outputs
-    circuit.nPublicInputs      // number of public inputs
-    circuit.nPrivateInputs     // number of private inputs
-    circuit.nInputs            // number of inputs ( nPublicInputs + nPrivateInputs)
-
-    circuit.outputIdx(i)       // returns the index of the i'th output
-    circuit.inputIdx(i)        // returns the index of the i'th input
-    circuit.inputPublicIdx(i)  // returns the index of the i'th public input
-    circuit.inputPrivateIdx(i) // returns the index of the i'th private input
-
-    // returns signal Idx given a signalId
-    // if the idx >= n , it is a constant
-    // if the idx == -1, the signal does not exist
-    circuit.signalId2idx(signalId);
-
-    // returns an array aliases names for a given signalId
-    circuit.signalNames(signalId)
-
-    // input is a key value object where keys are the signal names
-    //   of all the inputs (public and private)
-    // returns an array of values that represent the witness
-    circuit.generateWitness(input)
-```
-
-### Trusted setup
-
-```
-const setup = zkSnark.setup(circuit);
-fs.writeFileSink("myCircuit.vk_proof", JSON.stringify(setup.vk_proof), "utf8");
-fs.writeFileSink("myCircuit.vk_verifier", JSON.stringify(setup.vk_verifier), "utf8");
-setup.toxic  // Must be discarded.
-```
-
-### Generate proof
-
-```
-const circuitDef = JSON.parse(fs.readFileSync("myCircuit.cir", "utf8"));
-const circuit = new zkSnark.Circuit(circuitDef);
-const input = {
-    "main.pubIn1": "123",
-    "main.out1": "456"
-}
-const witness = circuit.generateWitness(input);
-const vk_proof = JSON.parse(fs.readFileSync("myCircuit.vk_proof", "utf8"));
-
-const {proof, publicSignals} = zkSnark.genProof(vk_proof, witness);
-```
-
-### Verifier
-
-```
-const vk_verifier = JSON.parse(fs.readFileSync("myCircuit.vk_verifier", "utf8"));
-
-if (zkSnark.isValid(vk_verifier, proof, publicSignals)) {
-    console.log("The proof is valid");
-} else {
-    console.log("The proof is not valid");
-}
-```

README.md

@@ -39,7 +39,7 @@ const circuit = new zkSnark.Circuit(circuitDef);
     circuit.nPublic; // number of public signals (nOutputs + nPublicInputs)
 
     // The array of signals is always sorted in this order:
-    // [ outputs, publicInputs, privedInputs, internalSignals, constants]
+    // [ outputs, publicInputs, 1, privedInputs, internalSignals, constants]
 
     // returns a,b and c coeficients of the `signalId` on a given `constrain`
     circuit.a(constrain, signalId)

src/prover.js

@@ -25,7 +25,8 @@ module.exports = function genProof(vk_proof, witness) {
     proof.pi_h = G1.zero();
 
 
-    for (let s= vk_proof.nPublic; s< vk_proof.nSignals; s++) {
+    // Skip public entries and the "1" signal that are forced by the verifier
+    for (let s= vk_proof.nPublic+1; s< vk_proof.nSignals; s++) {
 
         // pi_a  = pi_a  + A[s]  * witness[s];
         proof.pi_a  = G1.add( proof.pi_a, G1.mulEscalar( vk_proof.A[s], witness[s]));

src/verifier.js

@@ -10,12 +10,12 @@ const pairing = require("./pairing");
 
 module.exports = function isValid(vk_verifier, proof, publicSignals) {
 
-    let  full_pi_a = proof.pi_a;
     for (let s= 0; s< vk_verifier.nPublic; s++) {
-
         full_pi_a  = G1.add( full_pi_a, G1.mulEscalar( vk_verifier.A[s], publicSignals[s]));
     }
 
+    let  full_pi_a = G1.add(proof.pi_a, vk_verifier.A[vk_verifier.nPublic]);
+
     if (! Gt.equal(
         pairing( proof.pi_a , vk_verifier.vk_a ),
         pairing( proof.pi_ap , G2.g )))