Nokia Corporation

Envault Corporation Oy

Markku-Juhani Saarinen

Ville J Ollikainen

The invention concerns a method for writing data to a memory device arrangement comprising a first and a second memory device in which the first memory device comprises data blocks numbered with block numbers and the second memory device comprises at least one reference calculated from a data block digest and its physical block number. The invention is characterized in that it comprises the following steps: calculating the digest from at least part of the data block content, receiving at least one physical block number, to which the data block contents in the first memory device is stored, encrypting the data block content, storing the data block content to the first memory device to the position pointed by the physical block number, and storing or issuing a command to save the digest, or a number derived from it, and at least one said physical block number to the second memory device. Also a system, a computer program and server computer in accordance to the invention are presented.

Method and apparatus for implementing secure and selectively deniable file storage

A pseudo-random number generator (PRNG) for a cryptographic processing system is disclosed in which the PRNG is reseeded at each instance of input entropy and in which a standard timestamp variable used in determining random sequence outputs is replaced with a running counter. The method employed by the PRNG demonstrates increased resistance to iterative-guessing attacks and chosen-input attacks than those of previous technologies. The PRNG is suitable for use in, for example, a mobile telephone system for accomplishing secure communications.

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Helsinki, Finland

Markku-Juhani Saarinen