PhilJay/JWT

allprojects {
    repositories {
        maven { url 'https://jitpack.io' }
    }
}

dependencies {
    implementation 'com.github.PhilJay:JWT:1.2.6'
}

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

<dependency>
    <groupId>com.github.PhilJay</groupId>
    <artifactId>JWT</artifactId>
    <version>1.2.6</version>
</dependency>

    val gson = GsonBuilder().create()
 
    // generic JSON encoder
    val jsonEncoder = object : JsonEncoder<JWTAuthHeader, JWTAuthPayload> {
        override fun toJson(header: JWTAuthHeader): String {
            return gson.toJson(header, JWTAuthHeader::class.java)
        }
    
        override fun toJson(payload: JWTAuthPayload): String {
            return gson.toJson(payload, JWTAuthPayload::class.java)
        }
    }

    // Base64 encoder using apache commons
    private val encoder = object : Base64Encoder {
        override fun encodeURLSafe(bytes: ByteArray): String {
            return Base64.encodeBase64URLSafeString(bytes)
        }
    
        override fun encode(bytes: ByteArray): String {
            return Base64.encodeBase64String(bytes)
        }
    }

    // Base64 decoder using apache commons
    private val decoder = object : Base64Decoder {
        override fun decode(bytes: ByteArray): ByteArray {
            return Base64.decodeBase64(bytes)
        }
    
        override fun decode(string: String): ByteArray {
            return Base64.decodeBase64(string)
        }
    }

    val token = JWT.tokenApple("teamId", "keyId", "secret", jsonEncoder, encoder, decoder)

    val header = JWTAuthHeader(...)
    val payload = JWTAuthPayload(...)
    val token = JWT.token(Algorithm.ES256, header, payload, "secret", jsonEncoder, encoder, decoder)

    private val jsonDecoder = object : JsonDecoder<JWTAuthHeader, JWTAuthPayload> {

        override fun headerFrom(json: String): JWTAuthHeader {
            return gson.fromJson(json, JWTAuthHeader::class.java)
        }

        override fun payloadFrom(json: String): JWTAuthPayload {
            return gson.fromJson(json, JWTAuthPayload::class.java)
        }
    }

    val tokenString = "ey..." // a valid JWT as a String
    val t: JWTToken<JWTAuthHeader, JWTAuthPayload>? = JWT.decode(tokenString, jsonDecoder, decoder)
    
    // conveniently access properties of the token...
    val issuer = t?.payload?.iss

    val jwk: JWKObject = ... // fetch current JWK (public key) from Apple endpoint
    val tokenString = "ey..." // the token to validate / verify (obtained from Sign in with Apple)
    
    // turns JWK into RSA public key, returns true if validation is successful
    val valid = JWT.verify(tokenString, jwk, decoder) 

   'authentication' 'bearer $token'

   'apns-push-type' 'alert' // possible values are 'alert' or 'background'