Methods and systems for encrypting and decrypting data are described. In one embodiment, a computing system determines a first initialization vector (IV) from another IV and a sequence number of a block of information, and hashes the first IV to create a hash. The computing system then determines a first block from the first block of information and the first hash and enciphers the first block to generate a block of ciphertext. In another embodiment, the computing system deciphers the block of ciphertext to generate the first block, and determines the first IV from the other IV and a sequence number of a block of information. The computing system hashes the first IV to create a hash and determines a block of information corresponding to the first block of ciphertext from the first block and the hash.