# snarkjs-backup > zkSNARKs implementation in JavaScript Latest version **0.1.21** (published 2022-08-11) · GPL-3.0 license · 0 weekly downloads ## Install ```sh npm install snarkjs-backup pnpm add snarkjs-backup yarn add snarkjs-backup bun add snarkjs-backup ``` Provides the command `snarkjs`. ## Health **Score 30/100 (F)** — status: abandoned. Positive: no vulnerabilities; high maintenance score. Warnings: low downloads; no types; no esm support; pre 1.0. Negative: abandoned. ## Facts | | | |---|---| | Version | 0.1.21 | | Published | 2022-08-11 | | First published | 2022-08-11 | | Weekly downloads | 0 | | License | GPL-3.0 | | TypeScript types | none | | Module format | CommonJS | | Dependencies | 6 | | Unpacked size | 291.9 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 2040 | | Author | Jordi Baylina | | Maintainers | carole | | Keywords | zksnark, zcash, ethereum, zero, knowlage, cryptography, circuit | ## Links - npm: https://www.npmjs.com/package/snarkjs-backup - Repository: https://github.com/iden3/snarkjs - Homepage: https://github.com/iden3/snarkjs#readme - Issues: https://github.com/iden3/snarkjs/issues - npm.io page: https://npm.io/package/snarkjs-backup ## Dependencies (6) - [chai](https://npm.io/package/chai.md) ^4.2.0 - [yargs](https://npm.io/package/yargs.md) ^12.0.5 - [eslint](https://npm.io/package/eslint.md) ^5.16.0 - [keccak](https://npm.io/package/keccak.md) ^2.0.0 - [big-integer](https://npm.io/package/big-integer.md) ^1.6.43 - [escape-string-regexp](https://npm.io/package/escape-string-regexp.md) ^1.0.5 ## Alternatives - [@gemini-wallet/core](https://npm.io/package/@gemini-wallet/core.md) — 515.6K weekly downloads - [utility](https://npm.io/package/utility.md) — 416.6K weekly downloads - [@primno/dpapi](https://npm.io/package/@primno/dpapi.md) — 7.2K weekly downloads - [pi-readseek](https://npm.io/package/pi-readseek.md) — 3.7K weekly downloads - [@emilia-protocol/verify](https://npm.io/package/@emilia-protocol/verify.md) — 1.1K weekly downloads ## Recent versions - 0.1.21 (latest) — 2022-08-11 - 0.1.20 — 2022-08-11 ## README # snarkjs: JavaScript implementation of zkSNARKs. This is a JavaScript implementation of zkSNARK schemes. It allows the original 8points protocol and the Groth Protocol (3 point only and 3 pairings) 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. ### Tutorial. A good starting point [is this tutorial](https://github.com/iden3/circom/blob/master/TUTORIAL.md) Also this [video](https://www.youtube.com/watch?v=-9TJa1hVsKA) is a good starting point. ## Install. ```sh npm install snarkjs ``` ## Usage from command line. ```sh snarkjs --help ``` Will show all the info in how to use the cli. ## Usage from javascript ### Import. ```js const zkSnark = require("snarkjs"); ``` ### Load a circuit. ```js // "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. ```js // `signalId` can always be a number or an alias string circuit.nConstraints; // number of constraints circuit.nSignals; // number of signals circuit.nPublic; // number of public signals (nOutputs + nPublicInputs) // The array of signals is always sorted in this order: // [ 1, outputs, publicInputs, privateInputs, internalSignals, constants] // returns a,b and c coeficients of the `signalId` on a given `constraint` circuit.a(constraint, signalId) circuit.b(constraint, signalId) circuit.c(constraint, signalId) circuit.nOutputs // number of public outputs circuit.pubInputs // number of public inputs circuit.nPrvInputs // number of private inputs circuit.nInputs // number of inputs ( nPublicInputs + nPrivateInputs) circuit.nVars // number of variables ( not including constants (one is a variable) ) circuit.nSignals // number of signals ( including constants ) circuit.outputIdx(i) // returns the index of the i'th output circuit.inputIdx(i) // returns the index of the i'th input circuit.pubInputIdx(i) // returns the index of the i'th public input circuit.prvInputIdx(i) // returns the index of the i'th private input circuit.varIdx(i) // returns the index of the i'th variable circuit.constantIdx(i) // returns the index of the i'th constant circuit.signalIdx(i) // returns the index of the i'th signal // returns signal Idx given a signalId // if the idx >= n , it is a constant // if the idx == -1, the signal does not exist circuit.getSignalIdx(name); // returns an array aliases names of the i'th signal circuit.signalNames(i) // input is a key value object where keys are the signal names // of all the inputs (public and private) // returns an array of values representing the witness circuit.calculateWitness(input) ``` ### Trusted setup. ```js const setup = zkSnark.setup(circuit); fs.writeFileSync("myCircuit.vk_proof", JSON.stringify(setup.vk_proof), "utf8"); fs.writeFileSync("myCircuit.vk_verifier", JSON.stringify(setup.vk_verifier), "utf8"); setup.toxic // Must be discarded. ``` ### Generate proof. ```js 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.calculateWitness(input); const vk_proof = JSON.parse(fs.readFileSync("myCircuit.vk_proof", "utf8")); const {proof, publicSignals} = zkSnark.genProof(vk_proof, witness); ``` ### Verifier. ```js 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"); } ``` ## License snarkjs is part of the iden3 project copyright 2018 0KIMS association and published with GPL-3 license. Please check the COPYING file for more details. --- _Source: https://npm.io/package/snarkjs-backup · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._