class Aws::S3::EncryptionV2::DecryptHandler

def envelope_from_instr_file(context)
  suffix = context[:encryption][:instruction_file_suffix]
  possible_envelope = Json.load(context.client.get_object(
    bucket: context.params[:bucket],
    key: context.params[:key] + suffix
  ).body.read)
  extract_envelope(possible_envelope)
rescue S3::Errors::ServiceError, Json::ParseError
  nil
end