feat(jwt): add some useful methods to JWT so it can provide the essen…

…tial information

README.md

@@ -220,13 +220,21 @@ import JSONWebToken
 
 You can access [here](https://beatt83.github.io/jose-swift/documentation/jose_swift/) to the documentation.
 
+For more examples on how to use this library please try to check the unit tests, they are extensive and should provide more information.
+
 ## Modules
 
 ### JWK (JSON Web Key)
 JWK is a standard way to represent cryptographic keys in a JSON format, as defined in [RFC 7517](https://datatracker.ietf.org/doc/html/rfc7517). This module provides functionalities for generating, parsing, and managing JWKs, which are essential for encryption, decryption, and signing processes.
 
 ```swift
 let keyJWK = JWK(keyType: .rsa, algorithm: "A256GCM", keyID: rsaKeyId, e: rsaKeyExponent, n: rsaKeyModulus)
+// ---------------------
+let key = secp256k1.Signing.PrivateKey()
+let keyJWK = key.jwkRepresentation
+// ---------------------
+let key = Curve25519.KeyAgreement.PrivateKey()
+let publicKeyJWK = key.jwkRepresentation.publicKey
 ```
 
 ### JWS (JSON Web Signature)
@@ -252,7 +260,8 @@ Example:
 
 ```swift
 let payload = "Hello world".data(using: .utf8)!
-let keyJWK = ... //JWK key
+let key = secp256k1.Signing.PrivateKey()
+let keyJWK = key.jwkRepresentation
 
 let jws = try JWS(payload: payload, key: keyJWK)
 
@@ -298,6 +307,9 @@ JWE represents encrypted content using JSON-based data structures, following the
     - A128GCM (AES GCM using 128-bit key)
     - A192GCM (AES GCM using 192-bit key)
     - A256GCM (AES GCM using 256-bit key)
+
+3. **Compression Algorithms**:
+    - DEFLATE (zip)
 
 Example:
 
@@ -310,6 +322,7 @@ let serialization = try JWE(
     payload: payload,
     keyManagementAlg: .a256KW,
     encryptionAlgorithm: .a256GCM,
+    compressionAlgorithm: .zip,
     recipientKey: keyJWK
 )
 
@@ -362,11 +375,12 @@ Example:
 - Signed JWT
 
 ```swift
-let keyJWK = ... //JWK key
+let key = P256.Signing.PrivateKey()
+let keyJWK = key.jwkRepresentation
 let mockClaims = DefaultJWTClaims(
-    issuer: "testAlice",
-    subject: "Alice",
-    expirationTime: expiredAt
+    iss: "testAlice",
+    sub: "Alice",
+    exp: expiredAt
 )
 
 let jwt = try JWT.signed(
@@ -384,11 +398,12 @@ let verifiedPayload = verifiedJWT.payload
 - Encrypted JWT
 
 ```swift
-let keyJWK = ... //JWK key
+let key = Curve25519.KeyAgreement.PrivateKey()
+let keyJWK = key.jwkRepresentation
 let mockClaims = DefaultJWTClaims(
-    issuer: "testAlice",
-    subject: "Alice",
-    expirationTime: expiredAt
+    iss: "testAlice",
+    sub: "Alice",
+    exp: expiredAt
 )
 
 let jwt = try JWT.encrypt(

Sources/JSONWebToken/JWT+Error.swift

@@ -47,5 +47,11 @@ extension JWT {
 
         /// Error indicating a mismatch between the expected audience (`aud` claim) and the actual audience of the JWT.
         case audienceMismatch
+
+        // Error indicating that JWT formats supported are JWS strings and JWE strings
+        case unsupportedFormat
+
+        // Error indicating that JWT of JWE format cannot retrieve payload without decryption
+        case cannotRetrievePayloadFromJWE
     }
 }

Sources/JSONWebToken/JWT.swift

@@ -52,4 +52,85 @@ public struct JWT<C: JWTRegisteredFieldsClaims> {
             return jws.compactSerialization
         }
     }
+
+    public init(payload: C, format: Format) {
+        self.payload = payload
+        self.format = format
+    }
+
+    public init(jwtString: String) throws {
+        self.payload = try Self.getPayload(jwtString: jwtString)
+        self.format = try Self.jwtFormat(jwtString: jwtString)
+    }
+}
+
+public extension JWT {
+    static func getPayload<Payload: JWTRegisteredFieldsClaims>(jwtString: String) throws -> Payload {
+        return try JSONDecoder().decode(Payload.self, from: getPayload(jwtString: jwtString))
+    }
+
+    static func getPayload(jwtString: String) throws -> Data {
+        switch try jwtFormat(jwtString: jwtString) {
+        case .jwe:
+            throw JWTError.cannotRetrievePayloadFromJWE
+        case .jws(let jws):
+            return jws.payload
+        }
+    }
+
+    static func getIssuer(jwtString: String) throws -> String? {
+        let payload: DefaultJWTClaimsImpl = try getPayload(jwtString: jwtString)
+        return payload.iss
+    }
+
+    static func getSubject(jwtString: String) throws -> String? {
+        let payload: DefaultJWTClaimsImpl = try getPayload(jwtString: jwtString)
+        return payload.sub
+    }
+
+    static func getNotBeforeTime(jwtString: String) throws -> Date? {
+        let payload: DefaultJWTClaimsImpl = try getPayload(jwtString: jwtString)
+        return payload.nbf
+    }
+
+    static func getExpirationTime(jwtString: String) throws -> Date? {
+        let payload: DefaultJWTClaimsImpl = try getPayload(jwtString: jwtString)
+        return payload.exp
+    }
+
+    static func getIssuedAt(jwtString: String) throws -> Date? {
+        let payload: DefaultJWTClaimsImpl = try getPayload(jwtString: jwtString)
+        return payload.iat
+    }
+
+    static func getID(jwtString: String) throws -> String? {
+        let payload: DefaultJWTClaimsImpl = try getPayload(jwtString: jwtString)
+        return payload.jti
+    }
+
+    static func getAudience(jwtString: String) throws -> [String]? {
+        let payload: DefaultJWTClaimsImpl = try getPayload(jwtString: jwtString)
+        return payload.aud
+    }
+
+    static func getHeader(jwtString: String) throws -> Data {
+        switch try jwtFormat(jwtString: jwtString) {
+        case .jwe(let jwe):
+            return jwe.protectedHeaderData
+        case .jws(let jws):
+            return jws.protectedHeaderData
+        }
+    }
+
+    static func jwtFormat(jwtString: String) throws -> Format {
+        let components = jwtString.components(separatedBy: ".")
+        switch components.count {
+        case 3:
+            return try .jws(.init(jwsString: jwtString))
+        case 5:
+            return try .jwe(.init(compactString: jwtString))
+        default:
+            throw JWTError.somethingWentWrong
+        }
+    }
 }