ELECTRONIC BLOCK CIPHER DEVICE SUITABLE FOR OBFUSCATION

摘要

An electronic block cipher device for encrypting or decrypting a message block of digital data comprising a storage unit storing multiple substitution boxes in the form of look-up tables, the multiple substitution boxes together forming a substitution layer of a block cipher, the substitution layer being arranged to take a substitution layer input and transforming it into a substitution layer output, at least one substitution box being arranged to receive as input a combination of at least part of the outputs of more than one further substitution boxes in the same substitution layer, a control unit configured to apply the block cipher to the message block of digital data by applying a sequence of block cipher rounds to the message block, one of the block cipher rounds comprising the substitution layer.

主权项

1. An electronic block cipher device for encrypting or decrypting a message block of digital data according to a block cipher, the block cipher having rounds, a round comprising a substitution layer and a linear transformation layer, the electronic block cipher device comprising
a storage unit storing multiple non-linear substitution boxes in the form of look-up tables, the multiple substitution boxes together forming the substitution layer of the block cipher, wherein the substitution boxes in the substitution layer are obfuscated by encoding their input and output, the substitution layer being arranged to take a substitution layer input and transforming it into a substitution layer output, at least one substitution box of the multiple substitution boxes being arranged to receive as input a combination of at least part of the outputs of more than one further substitution boxes of the multiple substitution boxes in the same substitution layer, a control unit configured to apply the block cipher to the message block of digital data by applying a sequence of block cipher rounds to the message block, one of the block cipher rounds comprising the substitution layer.