Search key substitution in the encipherment of B-trees

This paper suggests an improvement to the scheme by Bayer and Metzger for the encipherment of B-Trees. Search keys are "disguised" instead of encrypted, and together with the data pointers and tree pointers which remain encrypted, prevents the opponent or attacker from recreating the correct shape of the B-Tree. Combinatorial block designs are used as a method to substitute the search keys contained within the nodes of the B-Tree. The substitution provides advantages in terms of the number of decryptions necessary to traverse the B-Tree, while the use of block designs are advantageous in terms of the small amount of information that needs to be kept secret. The method is aimed at enhancing the use of encryption for the nodes of the B-Tree, and not as a replacement of the encryption algorithm. Although in this paper it is used in the context of B-Trees, the method may be applicable to other record storage organizations.