react-native-rsa-oaep

React Native RSA-OAEP (SHA-256) encryption and decryption for iOS and Android. Compatible with Node.js crypto.privateDecrypt using RSA_PKCS1_OAEP_PADDING and oaepHash: 'sha256'.

Features

• RSA-OAEP with SHA-256 – Modern, secure padding (not PKCS#1 v1.5)
• Node.js 22+ compatible – Works with current Node.js without security reverts
• PEM support – PKCS#1 and PKCS#8/X.509 formats for public and private keys
• TypeScript – Includes type definitions

Installation

npm install react-native-rsa-oaep
# or
yarn add react-native-rsa-oaep

iOS

cd ios
pod install
cd ..

Android

No extra steps. The library uses React Native autolinking.

Usage

import { encryptOaep, decryptOaep } from 'react-native-rsa-oaep';

// Encrypt with public key (PEM)
const cipherB64 = await encryptOaep('hello world', publicKeyPem);

// Decrypt with private key (PEM)
const plainText = await decryptOaep(cipherB64, privateKeyPem);

Supported PEM formats

| Format | Header | |--------|--------| | Public (X.509/SPKI) | -----BEGIN PUBLIC KEY----- | | Public (PKCS#1) | -----BEGIN RSA PUBLIC KEY----- | | Private (PKCS#8) | -----BEGIN PRIVATE KEY----- | | Private (PKCS#1) | -----BEGIN RSA PRIVATE KEY----- |

Backend (Node.js)

Decrypt ciphertext produced by the mobile app:

const crypto = require('crypto');
const fs = require('fs');

const privateKey = fs.readFileSync('private.pem', 'utf8');
const cipherB64 = '...'; // from mobile encryptOaep()

const decrypted = crypto.privateDecrypt(
  {
    key: privateKey,
    passphrase: process.env.KEY_PASSPHRASE || '',
    padding: crypto.constants.RSA_PKCS1_OAEP_PADDING,
    oaepHash: 'sha256',  // required to match mobile
  },
  Buffer.from(cipherB64, 'base64')
);

console.log(decrypted.toString('utf8'));

API

encryptOaep(plainText: string, publicKeyPem: string): Promise<string>

Encrypts UTF-8 plaintext with an RSA public key. Returns base64-encoded ciphertext.

• plainText – String to encrypt
• publicKeyPem – PEM-encoded public key
• Returns – Base64 ciphertext
• Throws – On invalid input or encryption failure

decryptOaep(cipherB64: string, privateKeyPem: string): Promise<string>

Decrypts base64 ciphertext with an RSA private key. Returns UTF-8 plaintext.

• cipherB64 – Base64-encoded ciphertext
• privateKeyPem – PEM-encoded private key
• Returns – Decrypted string
• Throws – On invalid input or decryption failure

Requirements

• React Native >= 0.68
• iOS 11+
• Android API 21+ (minSdkVersion 21)

Troubleshooting

"RsaOaep native module not linked"

• Run pod install in ios/ and rebuild
• Ensure the package is in node_modules and autolinking is enabled

"Invalid public key" / "Invalid private key"

• Ensure the PEM includes headers (e.g. -----BEGIN PUBLIC KEY-----)
• Check that the key is valid and not corrupted

Backend decryption fails with OAEP error

• Use oaepHash: 'sha256' in crypto.privateDecrypt options
• Ensure the private key matches the public key used for encryption

License

MIT