JWT Signing Algorithms Explained

JWT Signing Algorithms Explained

JWT supports several categories of signing algorithms. Choosing the right one depends on your security requirements.

HMAC (HS256, HS384, HS512)

HMAC algorithms use a shared secret for both signing and verification.

Pros: Simple, fast, no key management | Cons: Secret must be shared securely

Best for: Internal services, single-server applications

RSA (RS256, RS384, RS512)

RSA uses a public-private key pair. The private key signs, the public key verifies.

Pros: Strong security, widely supported | Cons: Slower than HMAC

Best for: APIs where the verifier cannot hold the signing key

RSA-PSS (PS256, PS384, PS512)

A modern variant of RSA with probabilistic signature scheme.

Pros: Better security properties than RS* | Cons: Slightly slower, less library support

ECDSA (ES256, ES384, ES512)

Elliptic Curve Digital Signature Algorithm — smaller keys than RSA for equivalent security.

Pros: Smaller signatures, faster than RSA | Cons: Requires proper random nonce

EdDSA (Ed25519)

Modern Edwards-curve signature algorithm.

Pros: Fast, secure, constant-time | Cons: Newer — fewer libraries support it

Algorithm Security Overview