private async Task <IEnumerable <RsaKey> > DeleteRetiredKeysAsync(IEnumerable <RsaKey> keys)
{
var retiredKeys = keys.Where(_timeKeeper.IsRetired).ToArray();
foreach (var retiredKey in retiredKeys)
{
await _repository.DeleteKeyAsync(retiredKey.KeyId);
}
return(keys.Except(retiredKeys).ToArray());
}
