Question 1

How do I generate an RSA key pair with ursa?

Accepted Answer

Use the ursa.generatePrivateKey() method with parameters for modulus bits and exponent, such as ursa.generatePrivateKey(2048, 65537). This creates a private key that can be exported to PEM format using toPrivatePem().

Question 2

Ursa vs node-rsa: which one should I use?

Accepted Answer

Ursa provides lower-level OpenSSL bindings with direct control over padding modes and SSH key support, while node-rsa is a pure JavaScript implementation that may be easier to install but less performant. Choose ursa for native integration and node-rsa for portability.

Question 3

Can ursa be used for signing JWT tokens?

Accepted Answer

Yes, ursa can sign and verify hashes for JWT tokens using its sign() and verify() methods with algorithms like SHA256. However, you'll need to handle JWT encoding and decoding separately, as ursa only provides the cryptographic operations.

Question 4

What padding modes does ursa support for encryption?

Accepted Answer

Ursa supports RSA_PKCS1_OAEP_PADDING (default for public encryption) and RSA_PKCS1_PADDING, as listed in the constants section. These can be specified in the encrypt() and decrypt() methods for flexibility.

Question 5

Is ursa compatible with modern Node.js versions like 14 or 16?

Accepted Answer

The README states testing up to Node.js 0.12 and io.js, so compatibility with newer versions isn't guaranteed. You may encounter issues or need to rely on community pull requests for updates.

Question 6

How to convert a PEM key to SSH format using ursa?

Accepted Answer

Load the key with createPublicKey() or createPrivateKey(), then use the toPublicSsh() method on the key object. This outputs the SSH-format string suitable for authorized_keys files.

URSA

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