openssl_pbkdf2 Generates a PKCS5 v2 PBKDF2 string, defaults to SHA-1 &reftitle.description; stringopenssl_pbkdf2 stringpassword stringsalt intkey_length intiterations stringdigest_algorithm &warn.undocumented.func; &reftitle.parameters; password salt key_length iterations digest_algorithm &reftitle.returnvalues; Returns string&return.falseforfailure;.