An encryption technique is disclosed for encrypting a data segment comprising a plurality of data blocks, wherein the security and throughput of the encryption is enhanced by using blockwise independent bit vectors for reversible combination with the data blocks prior to key encryption. Preferably, the blockwise independent bit vectors are derived from a data tag associated with the data segment. Several embodiments are disclosed for generating these blockwise independent bit vectors. In a preferred embodiment, the data tag comprises a logical block address (LBA) for the data segment. Also disclosed herein is a corresponding decryption technique as well as a corresponding symmetrical encryption/decryption technique.