Compressing encrypted data without the encryption key

摘要

A method, system and computer program product are disclosed for compressing encrypted data, wherein the data is encrypted by using a block encryption algorithm in a chained mode of operation, and the encrypted data is comprised of a set of N encrypted blocks, C1 . . . CN. In one embodiment, the method comprises leaving block CN uncompressed, and compressing all of the blocks C1 . . . CN in a defined sequence using a Slepian-Wolf code. In an embodiment, the data is encrypted using an encryption key K, and the compressing includes compressing all of the blocks C1 . . . CN without using the encryption key. In one embodiment, the compressing includes outputting the blocks C1 . . . CN as a set of compressed blocks CmprC1 . . . CmprCN-1, and the method further comprises decrypting CN to generate a reconstructed block {tilde over (X)}n, and decrypting and decompressing the set of compressed blocks using {tilde over (X)}n.

主权项

1. A method of decompressing and decrypting a message comprised of a set of blocks including N-1 compressed encrypted blocks CEXN-1, . . . , CEX1, and one uncompressed encrypted block EXN, the method comprising:
receiving the N-1 compressed encrypted blocks CEXN-1, . . . CE1 and the uncompressed encrypted block EXN; and decrypting the set of blocks, including
decrypting EXN to generate a decrypted block XN, anddecompressing and decoding the blocks CEXN-1, . . . , CEX1 to generate decompressed and decrypted blocks XN-1, . . . , X1, including for each of the blocks CEXN-1, . . . , CEX1, using output from the decrypting of another block in the decompressing of said each block, includingstarting the decrypting the compressed encrypted blocks CEXN-1, . . . , CEX1 by using output from the decrypting of EXN to decrypt one of the blocks CEXN-1, . . . , CEX1 to generate another decrypted block.