However , Szabo 's method of double-spending protection was vulnerable to Sybil attacks . Szabo 's method of double protection was , however , vulnerable to Sybil attacks .
Walau bagaimanapun, kaedah Szabo untuk perlindungan perbelanjaan berganda terdedah kepada serangan Sybil. Kaedah perlindungan berganda Szabo adalah, bagaimanapun, terdedah kepada serangan Sybil.