Change a value from a JWT token header with Ktor pipeline-CodePudding

I have a big problem. I'm on a project, where the client requires the jwt to be encrypted. So the company came up with a method that encrypts and decrypts a string as follows.

String.crypto() : String

String.decrypto(): String

When the user successfully logs in, a token is generated, for example:

 asdf.asdf.asdf (this token does not exist, it's just an example of a 3-part token)

and is then encrypted to

asdfghhjkl;asdsffgghhasfsfgg

accessing the login controller there is the following logic

post("/sign_in") { 
  val user = call.request<UserModel>()
  val login = service.login(user)
  if login != null
  val token = service.createToken()
  call.respond(200, token.encrypt() )
  else 
  call.respond(401)
}

In this way an encryption token is sent by the request.

When I'm receiving an encrypted token, I can't use it, because I need to decrypt it first.

I need to create a pipeline before the token is validated. I'm trying as follows:

fun Application.configureJWT() {
  install(JWTPlugin)
}

private val JWTPlugin = createApplicationPlugin("JWTPlugin") {
  onCall { call ->
    val jwtEncrypted: String? = call.request.headers["Authorization"]
    val jwtDecrypted: String? = jwtEncrypted?.replace("Bearer", "")?.trim()?.decrypt()?.getOrThrow()
    jwtDecrypted?.let { call.response.headers.append("Authorization", "Bearer $it") }
  }
}

I can't use

call.principal<JWTPrincipal>()

because the passed jwt is encrypted (asdfghhjkl;asdsffgghhasfsfgg) and does not follow the 3-part pattern

header. payload.signature

and when the JWT class tries to validate it it will throw an exception

com.auth0.jwt.exceptions.JWTDecodeException: The token was expected to have 3 parts, but got 1.

So my question is this: What's missing in my pipeline, after decrypting the jwt, following the next phases of the pipeline and being able to use the already decrypted jwt correctly?

CodePudding user response：

You can use the JWTAuthenticationProvider.Config.authHeader method to redefine the parsing of the Authorization header:

jwt("auth-jwt") {
    authHeader { call ->
        val header = call.request.headers[HttpHeaders.Authorization] ?: return@authHeader null
        // Decode here

        try {
            parseAuthorizationHeader(header)
        } catch (cause: IllegalArgumentException) {
            null
        }
    }
/// ...
}