opensource free pure JavaScript cryptographic library supports RSA/RSAPSS/ECDSA/DSA signing/validation, ASN.1, PKCS#1/5/8 private/public key, X.509 certificate, CRL, OCSP, CMS SignedData, TimeStamp and CAdES and JSON Web Signature(JWS)/Token(JWT)/Key(JWK)

Usage no npm install needed!

<script type="module">
  import jsrsasign from 'https://cdn.skypack.dev/jsrsasign';



license bower npm version npm downloads jsdeliver downloads CDNJS githubsponsors cryptocurrency

The 'jsrsasign' (RSA-Sign JavaScript Library) is an opensource free cryptography library supporting RSA/RSAPSS/ECDSA/DSA signing/validation, ASN.1, PKCS#1/5/8 private/public key, X.509 certificate, CRL, OCSP, CMS SignedData, TimeStamp, CAdES JSON Web Signature/Token/Key in pure JavaScript.

Public page is https://kjur.github.io/jsrsasign .

Your bugfix and pull request contribution are always welcomed :)


  • 2021-Nov-21: 10.5.0 Release. Now supports secp521r1(P-521) ECDSA.
  • 2021-Apr-14: Security advisory and update for CVE-2021-30246 RSA signature validation vulnerability published
  • 2020-Oct-05: jsrsasign won Google Open Source Peer Bonus Award. Thank you Google.
  • 2020-Sep-23: 10.0.0 released for CMS SignedData related class including timestamp and CAdES architecture update
  • 2020-Aug-24: 9.1.0 released to new CRL APIs align with certificate
  • 2020-Aug-19: 9.0.0 released for major update of certificate and CSR generation and parsing without backward compatibility. Please see migration guide in detail.
  • 2020-Aug-02: twitter account @jsrsasign started for announcement. please follow.


  • Swiss Army Knife style all in one package crypto and PKI library
  • available on Node.js and browsers
  • Long live open source software from 2010
  • very easy API to use
  • powerful various format key loader and ASN.1 API
  • rich document and samples
  • no dependency to other library
  • no dependency to W3C Web Cryptography API nor OpenSSL
  • no dependency on newer ECMAScirpt function. So old browsers also supported.
  • very popular crypto library with 0.6M+ npm downloads/month


Node NPM

> npm install jsrsasign jsrsasign-util


> bower install jsrsasign

Or include in HTML from many CDN sites

> <script src="https://cdnjs.cloudflare.com/ajax/libs/jsrsasign/8.0.20/jsrsasign-all-min.js"></script>


Loading encrypted PKCS#5 private key:

> var rs = require('jsrsasign');
> var rsu = require('jsrsasign-util');
> var pem = rsu.readFile('z1.prv.p5e.pem');
> var prvKey = rs.KEYUTIL.getKey(pem, 'passwd');

Sign string 'aaa' with the loaded private key:

> var sig = new a.Signature({alg: 'SHA1withRSA'});
> sig.init(prvKey);
> sig.updateString('aaa');
> var sigVal = sig.sign();
> sigVal



published fixed version title/advisory CVE CVSS
2021Apr14 10.2.0 RSA signature validation vulnerability on maleable encoded message CVE-2021-30246 9.1
2020Jun22 8.0.19 ECDSA signature validation vulnerability by accepting wrong ASN.1 encoding CVE-2020-14966 5.5
2020Jun22 8.0.18 RSA RSAES-PKCS1-v1_5 and RSA-OAEP decryption vulnerability with prepending zeros CVE-2020-14967 4.8
2020Jun22 8.0.17 RSA-PSS signature validation vulnerability by prepending zeros CVE-2020-14968 4.2

Here is full published security advisory list.


If you like jsrsasign and my other project, you can support their development by donation through any of the platform/services below. Thank you as always.

Github Sponsors

You can sponsor jsrsasign with the GitHub Sponsors program.


You can donate cryptocurrency to jsrsasign using the following addresses:


Silver Sponsors