Node-RSA
RSA library for Node.js and browsers.
- Pure TypeScript
- Works in Node.js and modern browsers (no Buffer/crypto polyfills needed)
- Generating keys
- Encrypting and decrypting, with long-message support
- Signing and verifying
Table of contents
Example
import NodeRSA from 'node-rsa';
const key = new NodeRSA({ b: 2048 });
const text = 'Hello RSA!';
const encrypted = key.encrypt(text, 'base64');
console.log('encrypted:', encrypted);
const decrypted = key.decrypt(encrypted, 'utf8');
console.log('decrypted:', decrypted);
Installing
npm install node-rsa
Requires Node.js >= 20. For browsers, any bundler with conditional-exports support (Vite, Webpack 5, Rollup, esbuild, Parcel) picks the browser entry automatically.
Testing
npm test
Usage
Create instance
import NodeRSA from 'node-rsa';
const key = new NodeRSA([keyData, [format]], [options]);
keyData — string | Uint8Array | object — key data in one of the supported formats, or a generation spec.format — string — format id for importing the key. See Import/Export.options — object — additional settings (below).
Options
You can pass options as the second/third constructor argument, or later via key.setOptions().
environment — 'node' or 'browser'. Auto-detected from the loaded bundle; the option mainly exists to force the pure-JS engine on Node (setOptions({ environment: 'browser' })), bypassing the node:crypto fast path — useful if you need PSS with a custom MGF.bigIntImpl — 'native' or 'jsbn'. The browser bundle defaults to native ES2020 BigInt; the Node bundle uses jsbn. Switch only before importing/generating a key; switching on a populated instance throws.signingScheme — scheme used for sign / verify. One of 'pss' (default), 'pkcs1', or a 'scheme-hash' shorthand (e.g. 'pkcs1-sha512'). Object form is also accepted: { scheme: 'pss', hash: 'sha256', saltLength?: number, mgf?: MaskGenerationFunction }. Default hash is sha256.encryptionScheme — padding scheme for encrypt / decrypt. One of 'pkcs1_oaep' (default) or 'pkcs1'. Object form: { scheme: 'pkcs1_oaep', hash: 'sha1', mgf?, label? }. Default OAEP hash is sha1.
Note: Supported hash algorithms are 'md5', 'ripemd160', 'sha1', 'sha256', 'sha512' in both environments, plus 'md4', 'sha224', 'sha384' on Node. 'md4' additionally requires running Node with --openssl-legacy-provider.
Creating an "empty" key
const key = new NodeRSA();
Generate new 2048-bit key
const key = new NodeRSA({ b: 2048 });
Or:
key.generateKeyPair([bits], [exp]);
bits — number — key size in bits. 2048 by default.exp — number — public exponent. 65537 by default.
Load key from PEM string
const key = new NodeRSA(
'-----BEGIN RSA PRIVATE KEY-----\n' +
'MIIBOQIBAAJAVY6quuzCwyOWzymJ7C4zXjeV/232wt2ZgJZ1kHzjI73wnhQ3WQcL\n' +
'DFCSoi2lPUW8/zspk0qWvPdtp6Jg5Lu7hwIDAQABAkBEws9mQahZ6r1mq2zEm3D/\n' +
'VM9BpV//xtd6p/G+eRCYBT2qshGx42ucdgZCYJptFoW+HEx/jtzWe74yK6jGIkWJ\n' +
'AiEAoNAMsPqwWwTyjDZCo9iKvfIQvd3MWnmtFmjiHoPtjx0CIQCIMypAEEkZuQUi\n' +
'pMoreJrOlLJWdc0bfhzNAJjxsTv/8wIgQG0ZqI3GubBxu9rBOAM5EoA4VNjXVigJ\n' +
'QEEk1jTkp8ECIQCHhsoq90mWM/p9L5cQzLDWkTYoPI49Ji+Iemi2T5MRqwIgQl07\n' +
'Es+KCn25OKXR/FJ5fu6A6A+MptABL3r8SEjlpLc=\n' +
'-----END RSA PRIVATE KEY-----',
);
Import/Export keys
key.importKey(keyData, [format]);
key.exportKey([format]);
keyData — may be:
- PEM string (or a
Uint8Array/Buffer containing one)
Uint8Array containing raw DER- object with raw key components
format — string — format id for import/export.
Format string syntax
scheme-[key_type]-[output_type]
Scheme — node-rsa supports several:
'pkcs1' — public PEM starts with -----BEGIN RSA PUBLIC KEY-----, private with -----BEGIN RSA PRIVATE KEY-----.'pkcs8' — public PEM starts with -----BEGIN PUBLIC KEY-----, private with -----BEGIN PRIVATE KEY-----.'openssh' — public starts with ssh-rsa, private with -----BEGIN OPENSSH PRIVATE KEY-----.'components' — raw modulus/exponent and CRT params. For a private key all components must be present; for a public key only n and e. All components are Uint8Array except e, which may be Uint8Array or a plain number.
Key type — 'private' (default) or 'public'.
Output type:
'pem' — base64 PEM string with header/footer. Used by default.'der' — Uint8Array of binary DER.
Note: For import, if keyData is a PEM string (or a Uint8Array containing PEM), you can omit format. If it's raw DER, you must specify the format string.
Shortcuts and examples
'private' ≡ 'pkcs1' ≡ 'pkcs1-private' ≡ 'pkcs1-private-pem' — private key, PKCS#1, PEM.'public' ≡ 'pkcs8-public' ≡ 'pkcs8-public-pem' — public key, PKCS#8, PEM.'pkcs8' ≡ 'pkcs8-private' ≡ 'pkcs8-private-pem' — private key, PKCS#8, PEM.'pkcs1-der' ≡ 'pkcs1-private-der' — private key, PKCS#1, binary DER.'pkcs8-public-der' — public key, PKCS#8, binary DER.
Code example
const keyData = '-----BEGIN PUBLIC KEY----- ... -----END PUBLIC KEY-----';
key.importKey(keyData, 'pkcs8');
const publicDer = key.exportKey('pkcs8-public-der');
const privateDer = key.exportKey('pkcs1-der');
const hex = (s: string) =>
Uint8Array.from(s.match(/.{2}/g)!.map((b) => parseInt(b, 16)));
key.importKey({
n: hex('0086fa9ba066685845fc03833a9699c8baefb53cfbf19052a7f10f1eaa30488cec1ceb752bdff2df9fad6c64b3498956e7dbab4035b4823c99a44cc57088a23783'),
e: 65537,
d: hex('5d2f0dd982596ef781affb1cab73a77c46985c6da2aafc252cea3f4546e80f40c0e247d7d9467750ea1321cc5aa638871b3ed96d19dcc124916b0bcb296f35e1'),
p: hex('00c59419db615e56b9805cc45673a32d278917534804171edcf925ab1df203927f'),
q: hex('00aee3f86b66087abc069b8b1736e38ad6af624f7ea80e70b95f4ff2bf77cd90fd'),
dmp1: hex('008112f5a969fcb56f4e3a4c51a60dcdebec157ee4a7376b843487b53844e8ac85'),
dmq1: hex('1a7370470e0f8a4095df40922a430fe498720e03e1f70d257c3ce34202249d21'),
coeff: hex('00b399675e5e81506b729a777cc03026f0b2119853dfc5eb124610c0ab82999e45'),
}, 'components');
const publicComponents = key.exportKey('components-public');
console.log(publicComponents);
/*
{ n: Uint8Array(65) [0, 134, 250, 155, 160, 102, 104, 88, 69, 252, 3, 131, 58, ... ],
e: 65537 }
*/
To import only the public part use 'components-public':
key.importKey({
n: hex('0086fa9ba066685845fc03833a9699c8baefb53cfbf19052a7f10f1eaa30488cec1ceb752bdff2df9fad6c64b3498956e7dbab4035b4823c99a44cc57088a23783'),
e: 65537,
}, 'components-public');
Note: Buffer is a Uint8Array subclass on Node, so any code that passes Buffer.from(...) still works — the types document the cross-platform shape.
Properties
Key testing
key.isPrivate();
key.isPublic([strict]);
strict — boolean — if true, returns false when the key pair also contains a private exponent. Default false.
key.isEmpty();
Returns true if the instance has no key data.
Key info
key.getKeySize();
Returns key size in bits.
key.getMaxMessageSize();
Returns the max data size for a single encrypt operation, in bytes (scheme-dependent).
Encrypting/Decrypting
key.encrypt(buffer, [encoding], [source_encoding]);
key.encryptPrivate(buffer, [encoding], [source_encoding]); // encrypt with private key
Returns the encrypted data.
buffer — data to encrypt. May be string, Uint8Array (or Buffer on Node), number, plain object, or array. Objects and arrays are JSON-stringified first.encoding — output encoding: 'buffer' (default — returns Uint8Array), 'binary', 'hex', or 'base64'.source_encoding — only used when buffer is a string; how to interpret its bytes. Accepts 'utf8' (default), 'hex', 'base64', 'binary'.
key.decrypt(buffer, [encoding]);
key.decryptPublic(buffer, [encoding]); // decrypt with public key
Returns the decrypted data.
buffer — Uint8Array or base64-encoded string.encoding — output: 'buffer' (default, raw Uint8Array), 'utf8', 'hex', 'base64', 'binary', or 'json' (UTF-8 decoded + JSON.parse).
Note: encryptPrivate / decryptPublic always use PKCS#1 v1.5 type-1 padding (deterministic), regardless of the configured encryptionScheme.
Signing/Verifying
key.sign(buffer, [encoding], [source_encoding]);
Returns the signature. All arguments behave like encrypt.
key.verify(buffer, signature, [source_encoding], [signature_encoding]);
Returns true / false.
buffer — data that was signed; same shape as for encrypt.signature — Uint8Array or string, as produced by sign.source_encoding — encoding for buffer if it's a string. Default 'utf8'.signature_encoding — encoding of signature. One of 'buffer' (default), 'binary', 'hex', 'base64'.
Browser usage
The browser bundle (dist/index.browser.js) is published as ESM only and contains no Node-builtin imports — you don't need to polyfill Buffer, crypto, or process. Bundlers that honour the "browser" export condition (Vite, Webpack 5, Rollup, esbuild, Parcel) pick it up automatically. The bundle weighs ~114 KB raw / ~28 KB gzipped.
If your bundler doesn't resolve conditional exports, import the browser entry directly:
import NodeRSA from 'node-rsa/dist/index.browser.js';
Security notes
- PKCS#1 v1.5 encryption (
encryptionScheme: 'pkcs1') is vulnerable to Bleichenbacher-style padding-oracle attacks when used to decrypt attacker-controlled ciphertexts. The library closes the internal differential timing channel but cannot eliminate the binary valid/invalid oracle inherent to the scheme. Use the default 'pkcs1_oaep' for new code and for any path that touches attacker-controlled ciphertext.
Migrating
Migrating from 1.x? See MIGRATION.md for the behaviour-change summary and step-by-step walkthrough.
Changelog
Release notes and per-version changes are tracked in CHANGELOG.md.
License
Copyright (c) 2014 rzcoder
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Licensing for code used in rsa.ts and jsbn
Copyright (c) 2003-2005 Tom Wu
All Rights Reserved.
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
IN NO EVENT SHALL TOM WU BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER
RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER OR NOT ADVISED OF
THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT
OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
In addition, the following condition applies:
All redistributions must retain an intact copy of this copyright notice
and disclaimer.
Acknowledgements
- Tom Wu — original jsbn BigInteger and RSA implementations
- Paul Miller — @noble/hashes v2.x, audited synchronous hash functions (MD5, RIPEMD-160, SHA-1/2 family) used by the browser bundle
