Koninklijke Philips Corporation N.V.

Nxp B.v.

Timothy Kerins

Klaus Kursawe

Pim Theo Tuyls

It is described a method for encrypting and a method for decrypting at least a portion () of a dataset being stored in a memory (), wherein the dataset has at least two dimensions. The described multi-dimensional cryptographic methods comprise forming a first keystream () being assigned to a first dimension of the dataset and forming a second keystream () being assigned to a second dimension of the dataset. The encrypting method further comprises encrypting each data packet of the portion () of the dataset by using a combination of the first keystream () and the second keystream (). The decrypting method further comprises decrypting each data packet of the portion () of the dataset by using a combination of the first keystream () and the second keystream (). It is further described a method for temporarily storing at least a portion () of a dataset into a memory () and a device for handling a dataset, which method and which device take advantage of the above-described encrypting method and/or the above-described decrypting method.

Encryption and decryption of a dataset in at least two dimensions

The invention provides a method of generating arbitrary numbers given a seed, characterized by providing a challenge derived from the seed to a physical token, receiving an initial response from the physical token, combining the initial response with helper data associated with the challenge to produce a stable response, and generating the arbitrary numbers using a pseudo-random number generator using the stable response as a seed for the generator. Preferably one or more of these pseudo-random permutations are used as one or more round function(s) in a Feistel block cipher. The generated arbitrary numbers may also be used to create a cryptographic key.

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Eindhoven, Netherlands

Timothy Kerins