public function fetch($keyId)
    {
        if (isset($this->keys[$keyId])) {
            return $this->keys[$keyId];
        } else {
            throw new KeyStoreException("Key '$keyId' not found");
        }
    }
public function fetch($keyId)
    {
        if (isset($this->keys[$keyId])) {
            return $this->keys[$keyId];
        } else {
            throw new KeyStoreException("Key '$keyId' not found");
        }
    }
@param string $keyId

@return Key

@throws KeyStoreException