Simple console app verifying the client app integrity token with Play API: https://developer.android.com/google/play/integrity/verdict#decrypt-verify

PlayIntegrityTokenVerify.kt

// https://developer.android.com/google/play/integrity/verdict#decrypt-verify

//   implementation 'com.google.api-client:google-api-client:1.32.2'
//   implementation 'com.google.apis:google-api-services-playintegrity:v1-rev20220211-1.32.1'


package com.jraska.github.client.identity.integrity

import com.google.api.client.googleapis.auth.oauth2.GoogleCredential
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport
import com.google.api.client.json.gson.GsonFactory
import com.google.api.services.playintegrity.v1.PlayIntegrity
import com.google.api.services.playintegrity.v1.PlayIntegrityScopes
import com.google.api.services.playintegrity.v1.model.DecodeIntegrityTokenRequest
import java.io.File
import java.io.FileInputStream

fun main(args: Array<String>) {
  val token = args[0]
  val jsonCredentialsFilePath = args[1]

  if (!File(jsonCredentialsFilePath).exists()) {
    throw IllegalArgumentException("Credentials JSON was not found on path: '$jsonCredentialsFilePath'")
  }

  val playIntegrity = playIntegrity(jsonCredentialsFilePath)

  val tokenRequest = DecodeIntegrityTokenRequest()
  tokenRequest.integrityToken = token

  val response = playIntegrity.v1()
    .decodeIntegrityToken("com.jraska.github.client", tokenRequest)
    .execute()

  println(response)
}

private fun playIntegrity(credentialsFilePath: String): PlayIntegrity {
  val credentials = GoogleCredential.fromStream(FileInputStream(credentialsFilePath))
    .createScoped(listOf(PlayIntegrityScopes.PLAYINTEGRITY))

  return PlayIntegrity.Builder(
    GoogleNetHttpTransport.newTrustedTransport(),
    GsonFactory.getDefaultInstance(),
    credentials
  ).setApplicationName("github-client-integrity-verifier").build()
}