  ExpiringCryptoKey& current() {
    map<uint64_t, ExpiringCryptoKey>::iterator p = secrets.begin();
    ++p;
    return p->second;
  }
  ExpiringCryptoKey& current() {
    map<uint64_t, ExpiringCryptoKey>::iterator p = secrets.begin();
    ++p;
    return p->second;
  }