@borderless/web-jwt/dist/index.js

Small JWT library using the Web Crypto API

import { decode, encodeUrl as encode } from "@borderless/base64";
/**
 * JWT none algorithm support.
 */
export const NONE_KEY = Symbol("none");
const encoder = new TextEncoder();
const decoder = new TextDecoder();
/**
 * Decode results for invalid JWTs.
 */
export const NOOP_JWT = {
    header: {},
    payload: {},
    data: new Uint8Array(0),
    signature: new Uint8Array(0),
};
/**
 * Decode the JWT using base64url and JSON.
 */
export function decodeJwt(token) {
    try {
        const parts = token.split(".", 4);
        if (parts.length !== 3)
            return NOOP_JWT;
        const header = JSON.parse(decoder.decode(decode(parts[0])));
        const payload = JSON.parse(decoder.decode(decode(parts[1])));
        const signature = decode(parts[2]);
        // Sanity check JWT shape.
        if (header !== null &&
            typeof header === "object" &&
            (header.typ === undefined || header.typ === "JWT") &&
            (header.alg === undefined || typeof header.alg === "string") &&
            (header.kid === undefined || typeof header.kid === "string") &&
            payload !== null &&
            typeof payload === "object") {
            const data = encoder.encode(`${parts[0]}.${parts[1]}`);
            return { header, payload, data, signature };
        }
    }
    catch {
        // Noop.
    }
    return NOOP_JWT;
}
/**
 * Verify the JWT contents by deriving the signature from the content.
 */
export async function verifyJwt(raw, key) {
    if (key === NONE_KEY)
        return raw.signature.length === 0; // Support alg none.
    return crypto.subtle.verify(key.algorithm, key, raw.signature, raw.data);
}
/**
 * Stringify a JWT payload and sign using crypto key.
 */
export async function encodeJwt(header, payload, key) {
    const rawHeader = encode(encoder.encode(JSON.stringify(header)));
    const rawPayload = encode(encoder.encode(JSON.stringify(payload)));
    if (key === NONE_KEY)
        return `${rawHeader}.${rawPayload}.`; // Support alg none.
    const data = encoder.encode(`${rawHeader}.${rawPayload}`);
    const signature = await crypto.subtle.sign(key.algorithm, key, data);
    return `${rawHeader}.${rawPayload}.${encode(signature)}`;
}
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