ECDSA
also: Elliptic Curve Digital Signature Algorithm
ECDSA (Elliptic Curve Digital Signature Algorithm) is a cryptographic algorithm for creating and verifying digital signatures using elliptic curve mathematics, widely used in SSH keys and TLS certificates.
ECDSA is a modern public-key cryptography method that creates digital signatures—a way to prove that data hasn't been tampered with and came from a trusted source. Unlike RSA, which relies on the difficulty of factoring large numbers, ECDSA uses the mathematics of elliptic curves, achieving comparable security with much shorter keys.
On Linux systems, ECDSA is commonly used for SSH authentication. Instead of generating an RSA key pair with ssh-keygen -t rsa, you can use ssh-keygen -t ecdsa to create an ECDSA key. A 256-bit ECDSA key provides roughly the same security as a 3072-bit RSA key, making ECDSA more efficient for modern systems.
ECDSA is also used in TLS/SSL certificates, blockchain technologies, and system signatures. You'll often see ECDSA keys in your ~/.ssh directory alongside RSA keys, and many modern Linux distributions now prefer ECDSA or its successor Ed25519 over traditional RSA for new deployments.