Node.js crypto.publicEncrypt() Method

The crypto.publicEncrypt() method is an inbuilt application programming interface of the crypto module which is used to encrypt the stated content of the buffer with the parameter 'key'. Syntax:

crypto.publicEncrypt( key, buffer )

Parameters: This method accept two parameters as mentioned above and described below:

key: This parameter holds Object, string, Buffer, or KeyObject type of data and contains five parameters which are as follows:
1. key: It is a 'PEM' encoded public key or private key. It is of type string, Buffer, and KeyObject.
2. oaepHash: It is the hash function of type string which is used for 'OAEP' padding. And the default value is 'sha1'.
3. oaepLabel: It is the label which is used for 'OAEP' padding. And if it's not specified, then no label is used. It is of type Buffer, TypedArray or DataView.
4. passphrase: It is an optional passphrase for the private key which is either string or buffer.
5. padding: It is an optional padding value which is defined in crypto.constants, which can be crypto.constants.RSA_NO_PADDING, crypto.constants.RSA_PKCS1_PADDING, or crypto.constants.RSA_PKCS1_OAEP_PADDING. It is of type crypto.constants.
buffer: It is of type Buffer, TypedArray, or DataView.

Return Value: It returns a new Buffer with the encrypted content. Below example illustrate the use of crypto.publicEncrypt() method in Node.js: Example 1:

javascript

// Node.js program to demonstrate the 
// crypto.publicEncrypt() method

// Including crypto and fs module
const crypto = require('crypto');
const fs = require("fs");

// Using a function generateKeyFiles
function generateKeyFiles() {

    const keyPair = crypto.generateKeyPairSync('rsa', {
        modulusLength: 520,
        publicKeyEncoding: {
            type: 'spki',
            format: 'pem'
        },
        privateKeyEncoding: {
        type: 'pkcs8',
        format: 'pem',
        cipher: 'aes-256-cbc',
        passphrase: ''
        }
    });
     
    // Creating public key file 
    fs.writeFileSync("public_key", keyPair.publicKey);
}

// Generate keys
generateKeyFiles();

// Creating a function to encrypt string
function encryptString (plaintext, publicKeyFile) {
    const publicKey = fs.readFileSync(publicKeyFile, "utf8");

    // publicEncrypt() method with its parameters
    const encrypted = crypto.publicEncrypt(
         publicKey, Buffer.from(plaintext));
    return encrypted.toString("base64");
}

// Defining a text to be encrypted
const plainText = "GfG";

// Defining encrypted text
const encrypted = encryptString(plainText, "./public_key");

// Prints plain text
console.log("Plaintext:", plainText);

// Prints encrypted text
console.log("Encrypted: ", encrypted);

Output:

Plaintext: GfG
Encrypted:  l0touwFaNv1DIgPE365VQD0G4rg+IbRD5G6IBQ1arLgWtFOStKO7duYJ6/JzlOJl3eBG7obqzAEJ0V2WrxtYRTg=

Example 2:

javascript

// Node.js program to demonstrate the 
// crypto.publicEncrypt() method

// Including crypto and fs module
const crypto = require('crypto');
const fs = require("fs");

// Using a function generateKeyFiles
function generateKeyFiles() {

    const keyPair = crypto.generateKeyPairSync('rsa', {
        modulusLength: 520,
        publicKeyEncoding: {
            type: 'spki',
            format: 'pem'
        },
        privateKeyEncoding: {
        type: 'pkcs8',
        format: 'pem',
        cipher: 'aes-256-cbc',
        passphrase: ''
        }
    });
     
    // Creating public key file 
    fs.writeFileSync("public_key", keyPair.publicKey);
}

// Generate keys
generateKeyFiles();

// Creating a function to encrypt string
function encryptString (plaintext, publicKeyFile) {
    const publicKey = fs.readFileSync(publicKeyFile, "utf8");

    // publicEncrypt() method with its parameters
    const encrypted = crypto.publicEncrypt(
             publicKey, Buffer.from(plaintext));
    return encrypted;
}

// Defining a text to be encrypted
const plainText = "Hello!";

// Defining encrypted text
const encrypted = encryptString(plainText, "./public_key");

// Prints plain text
console.log("Plaintext:", plainText);

// Prints buffer
console.log("Buffer: ", encrypted);

Output:

Plaintext: Hello!
Buffer:

Reference: https://nodejs.org/api/crypto.html#crypto_crypto_publicencrypt_key_buffer

Node.js crypto.publicEncrypt() Method

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