25. The apparatus of claim 24 , wherein the query is an AND query.
25. The apparatus of claim 24 , wherein the query is an AND query. 26. The apparatus of claim 25 , wherein computing the first Bloom filter length, L s , for the first set, D1, having a maximum keyword length of b, further comprises computing according to the following equation: L s = (  D ⁢ ⁢ 1  ( ln ⁢ ⁢ 2 ) 2 ⁢ ) * ln ⁡ ( b ⁡ ( ln ⁢ ⁢ 2 ) 2 ) and wherein computing first number of hash functions, r s , for the first set, D1, further comprises computing according to the following equation: r s = ( L s  D ⁢ ⁢ 1  ) * ln ⁢ ⁢ 2.