sample_id_token_for_token_exchange.rb

require 'json/jwt'

rsa_key = OpenSSL::PKey::RSA.new <<-PEM
  :
PEM

claims = {
  iss: 'https://auth.server.example.com',
  sub: 'user-98765',
  aud: [
    'client-12345#native-app',
    'client-12345#backend-server'
  ],
  azp: 'client-12345#native-app',
  scopes: [
    'email',
    'profile',
    'status/read',
    'status/write'
  ],
  may_act: {
    iss: 'https://auth.server.example.com',
    sub: 'client-12345#backend-server'
  },
  cnf: {
    code_challange: 'E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM',
    code_challange_method: :S256
  },
  exp: 1.hours.from_now,
  iat: Time.now
}

id_token = JSON::JWT.new(claims).sign rsa_key