1. A computer-implemented method for searching phrases in an encrypted search index, the method comprising: providing an encrypted search index including a plurality of encrypted phrases; providing a search query to be applied on the search index, the search query including set of unencrypted phrase(s) to be searched; providing a master key; providing, based on the master key, a set of encryption key(s) for each phrase of the set of unencrypted phrase(s); generating a set of encrypted phrase(s) respectively corresponding to the set of unencrypted phrase(s) by encrypting the each unencrypted phrase of the set of unencrypted phrase(s) respectively based on its corresponding set of encryption key(s); generating a set of encrypted search query(ies) corresponding to the set of encrypted phrase(s); and providing the set of encrypted search query(ies) to a search engine designed to perform searches on the encrypted search index.