Add JWT

Closes #13

src/jwt.ts

@@ -0,0 +1,81 @@
+import {Result} from 'result'
+import * as jose from 'jose'
+
+export type JWTstring = `${string}.${string}.${string}`
+export type JWTalgorithm = "HS256" | "HS512" | "ES256" | "ES512" | "EdDSA"
+export type Key = jose.KeyLike | Uint8Array
+/** KeyPair for asymmetric algorithms, [PrivKey, PubKey] */
+export type KeyPair = [Key, Key]
+
+export class JWTcontext {
+    public constructor(
+        private readonly key: Key | KeyPair,
+        private readonly alg: JWTalgorithm,
+    ) {}
+
+    public static async gen_key(alg: JWTalgorithm, extractable: boolean = false) : Promise<Key | KeyPair> {
+        switch (alg) {
+            case "HS256":
+            case "HS512":
+                return jose.generateSecret(alg, { extractable })
+            case "EdDSA":
+            case "ES256":
+            case "ES512":
+            {
+                const key = await jose.generateKeyPair(alg)
+                return [key.privateKey, key.publicKey]
+            }
+        }
+    }
+
+    public async sign<T extends jose.JWTPayload>(message: T, set_issued: boolean = false, exp?: number | string | Date, audience?: string | string[], issuer?: string): Promise<JWT<T>> {
+        let jwt = new jose.SignJWT({payload: message}).setProtectedHeader({ alg: this.alg })
+
+        if (set_issued) jwt = jwt.setIssuedAt()
+        if (issuer !== undefined) jwt = jwt.setIssuer(issuer)
+        if (audience !== undefined) jwt = jwt.setAudience(audience)
+        if (exp !== undefined) jwt = jwt.setExpirationTime(exp)
+
+        const key = this.get_key(true)
+        const res = await jwt.sign(key) as JWTstring
+
+        return new JWT<T>(res)
+    }
+
+    public async verify<T>(jwt: JWT<T>, audience?: string | string[], issuer?: string | string[]): Promise<Result<T>> {
+        const key = this.get_key(false)
+
+        try {
+            let payload = await jose.jwtVerify(jwt.jwt, key)
+            return Result.ok(payload.payload.payload as T)
+        } catch(_) {}
+
+        return Result.error([])
+    }
+
+    private get_key(sign: boolean) : Key {
+        switch (this.alg) {
+            case "HS256":
+            case "HS512":
+                return this.key as Key
+            case "ES256":
+            case "ES512":
+            case "EdDSA":
+                return (this.key as KeyPair)[sign ? 0 : 1]
+        }
+    }
+}
+
+export class JWT<T> {
+    public constructor(
+        public readonly _jwt: `${string}.${string}.${string}`
+    ) {}
+
+    public get payload() : T {
+        return jose.decodeJwt(this.jwt).payload as T
+    }
+
+    public get jwt() : JWTstring {
+        return this._jwt
+    }
+}