jwt

jwt — JSON Web Tokens for EZ

Version: 1.0 Import: use "jwt" File: C:\ezlib\jwt\main.ez

Overview

The jwt library provides encoding and decoding of JSON Web Tokens (JWT) using the industry-standard HS256 (HMAC-SHA256) algorithm. It relies on the native cryptographic functions provided by crypto.

Quick Start

use "jwt"

SECRET = "my-super-secret-key-123"

# 1. Create a payload dictionary
payload = {
    "sub": "user_42",
    "role": "admin",
    "exp": clock() + 3600000  # Expires in 1 hour
}

# 2. Encode to a JWT string
token = JWT.encode(payload, SECRET)
out "Generated Token: " + token

# 3. Decode and verify the JWT string
try {
    decodedPayload = JWT.decode(token, SECRET)
    out "Decoded Subject: " + decodedPayload["sub"]
} catch e {
    out "Verification failed: " + str(e)
}

Model: JWT

JWT.encode(payload, secret) → string

Generates an HS256 JWT string.

Parameters:

• payload — A dictionary containing the claims to embed in the token.
• secret — The secret key string used to sign the token.

Returns: A standard header.payload.signature JWT string encoded in Base64Url format.

JWT.decode(token, secret) → dict

Decodes a JWT and verifies its HS256 signature.

Parameters:

• token — The JWT string to verify.
• secret — The secret key string that was used to sign the token.

Returns: The decoded payload dictionary.

Throws:

• "jwt: Invalid token format" if the token does not have 3 parts.
• "jwt: Signature verification failed" if the signature does not match or the token was tampered with.
• "jwt: Unsupported algorithm" if the header does not specify HS256.

Notes

• This library uses Base64Url encoding (as required by the JWT RFC 7519), which makes the generated tokens safe to use in URLs without escaping.
• It only supports symmetric HS256. Asymmetric algorithms (like RS256) are not currently supported by crypto.