RSAKEY Class: Secure Signing and Verification with RSA-PSS

This document explains the RSAKEY class, which provides functionalities for signing and verifying data using the RSA public-key cryptography algorithm with Probabilistic Signature Scheme (PSS) padding. It supports SHA-256, SHA-384, and SHA-512 hashing algorithms and allows customization of the salt length.

Functionality

  • Signing: Creates a digital signature for a given message using a provided private key.
  • Verification: Validates a signature for a message using a corresponding public key.

Supported Features

  • RSA-PSS padding for enhanced security.
  • SHA-256, SHA-384, and SHA-512 hashing algorithms.
  • Customizable salt length for PSS padding (optional).

Usage

1. Constructor:

import { RSAKEY } from './dist/RSAKEY.js'
const rsaKey = new RSAKEY(privateKeyPemString, options);
  • privateKeyPemString: A string containing the private key in PEM format.
  • options (optional): An object with the following properties (defaults provided):
    • sha: {number} The desired hashing algorithm (256, 384, or 512; defaults to 256).
    • saltLength: {number} The salt length for PSS padding (defaults to hash.length/8).

2. Signing:

const signature = rsaKey.sign(message);
  • message: {Uint8Array} The data to be signed.
  • Returns: {Uint8Array} The generated signature.

3. Verification:

const isValid = rsaKey.verify(publicKeyObject, message, signature);
  • message: {Uint8Array} The data that was signed.
  • signature: {Uint8Array} The signature to be verified (byte array).
  • publicKeyObject: {n:bigInt, e:bigInt} An object containing modulus - n and public exponent - e.
  • Returns: consistent if the signature is valid, inconsistent otherwise.

Example

const privateKeyPem = '-----BEGIN RSA PRIVATE KEY-----...\n-----END RSA PRIVATE KEY-----';
const message = new TextEncoder().encode('This is the message to be signed');

const rsaKey = new RSAKEY(privateKeyPem); // Use default options (SHA-256)

const signature = rsaKey.sign(message);

// ... (send the message and signature to another party)

const publicKeyPem = '-----BEGIN RSA PUBLIC KEY-----...\n-----END RSA PUBLIC KEY-----';
const isValid = rsaKey.verify(message, signature, publicKeyPem);

if (isValid=='consistent') {
  console.log('Signature is valid!');
} else {
  console.error('Signature verification failed!');
}

This RSAKEY class provides a convenient way to implement secure signing and verification using RSA-PSS with various SHA hashing options. By following these guidelines, you can effectively leverage this class for your cryptographic needs.

Notes

  • Please let me know for any improvement or feedback.

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