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    1.0.4 • Public • Published

    Universal Module for Elliptic Curve Cryptography (ECDSA and ECDH) in JavaScript

    npm version License: MIT

    WARNING: At this time this solution should be considered suitable for research and experimentation, further code and security review is needed before utilization in a production application.

    Introduction and Overview

    This library is designed to 'universally' provide an elliptic curve cryptography functions, i.e., it works both on most modern browsers and on Node.js just by importing from NPM/source code. Note that in the design principle, the library fully utilizes native APIs like WebCrypto API to accelerate its operation if available. This library provides APIs to employ ECDSA, ECDH and their key generation, i.e., sign, verify, generateKey and deriveSecret.


    At your project directory, do either one of the following.

    • From npm/yarn:
      $ npm install --save js-crypto-ec // npm
      $ yarn add js-crypto-ec // yarn
    • From GitHub:
      $ git clone
      $ cd js-crypto-utils/packages/js-crypto-ec
      & yarn build

    Then you should import the package as follows.

    import ec from 'js-crypto-ec'; // for npm
    import ec from 'path/to/js-crypto-ec/dist/index.js'; // for github

    The bundled file is also given as js-crypto-ec/dist/jscec.bundle.js for a use case where the module is imported as a window.jscec object via script tags.


    This library always uses JWK-formatted keys (RFC7517) to do any operations. If you utilize keys of other format, like PEM, please use js-crypto-key-utils to convert them to JWK.

    Key generation

    elliptic.generateKey('P-256').then( (key) => {
      // now you get the JWK public and private keys
      const publicKey = key.publicKey;
      const privateKey = key.privateKey;

    Sign and verify

    const publicJwk = {kty: 'EC', crv: 'P-256', x: '...', y: '...'}; // public key
    const privateJwk = {ktyp: 'EC', crv: 'P-256', x: '...', y: '...', d: '...'}; // paired private key
    const msg = ...; // Uint8Array
    // sign
      'raw' // output signature is not formatted. DER-encoded signature is available with 'der'.
      ).then( (signature) => {
      // now you get the signature in Uint8Array
      return ec.verify(
        'raw' // input signature is not formatted. DER-encoded signature is available with 'der'.
    }).then( (valid) => {
      // now you get the result of verification in boolean

    Derive shared secret

    const publicJwkA = {kty: 'EC', crv: 'P-256', x: '...', y: '...'}; // public key of player A
    const privateJwkA = {ktyp: 'EC', crv: 'P-256', x: '...', y: '...', d: '...'}; // paired private key of player A
    const publicJwkB = {kty: 'EC', crv: 'P-256', x: '...', y: '...'}; // public key of player B
    const privateJwkB = {ktyp: 'EC', crv: 'P-256', x: '...', y: '...', d: '...'}; // paired private key of player B
    // At A's side
    const sharedAtPlayerA = ec.deriveSecret(publicJwkB, privateJwkA).then( (secretAtA) => {
      // now you get the shared secret from my (player A's) private key and player B's public key
    // At B's side
    const sharedAtPlayerB = ec.deriveSecret(publicJwkA, privateJwkB).then( (secretAtB) => {
      // now you get the shared secret from my (player B's) private key and player A's public key

    NOTE: We SHOULD NOT use the derived secret as an encryption key directly. We should employ an appropriate key derivation procedure like HKDF to use the secret for symmetric key encryption.


    At this point, this library supports the following curve for elliptic curve cryptography.

    • P-256 (secp256r1)
    • P-384 (secp384r1)
    • P-521 (secp521r1)
    • P-256K (secp256k1)


    Licensed under the MIT license, see LICENSE file.


    npm i js-crypto-ec

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