jsonwt#

JSON Web Token (JWT) and CBOR Web Token (CWT) implementation for OCaml.

Overview#

A type-safe implementation of JWT (RFC 7519) and CWT (RFC 8392) with full support for:

• JWT parsing and creation - Compact serialization format
• Signature verification - HMAC, RSA, ECDSA, and EdDSA algorithms
• Claims validation - Expiration, not-before, issuer, audience checks
• JSON Web Key (JWK) - Key representation per RFC 7517
• Nested JWTs - Recursive parsing with depth limits
• CBOR Web Tokens - RFC 8392 for constrained environments

Installation#

opam install jsonwt

Usage#

Parsing and Verifying a JWT#

let token_string = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..." in
match Jsonwt.parse token_string with
| Ok jwt ->
    let key = Jsonwt.Jwk.symmetric "secret-key" in
    (match Jsonwt.verify ~key jwt with
    | Ok () -> print_endline "Valid signature"
    | Error e -> print_endline (Jsonwt.error_to_string e))
| Error e -> print_endline (Jsonwt.error_to_string e)

Creating a JWT#

let header = Jsonwt.Header.make ~typ:"JWT" Jsonwt.Algorithm.HS256 in
let claims = Jsonwt.Claims.(
  empty
  |> set_iss "https://example.com"
  |> set_sub "user123"
  |> set_exp (Ptime.of_float_s 1700000000.0 |> Option.get)
  |> build
) in
let key = Jsonwt.Jwk.symmetric "secret-key" in
match Jsonwt.create ~header ~claims ~key with
| Ok jwt -> print_endline (Jsonwt.encode jwt)
| Error e -> print_endline (Jsonwt.error_to_string e)

Supported Algorithms#

References#

• RFC 7519 - JSON Web Token (JWT)
• RFC 7515 - JSON Web Signature (JWS)
• RFC 7517 - JSON Web Key (JWK)
• RFC 7518 - JSON Web Algorithms (JWA)
• RFC 8392 - CBOR Web Token (CWT)

License#

ISC