Abstract: A method of storing an amount of data D in association with a device, the method comprising: obtaining a characteristic C of the device; generating error correction data R for the characteristic C, the error correction data R enabling correction of up to a predetermined number of errors in a version of the characteristic C; combining the characteristic C with the amount of data D and an authentication key K to generate storage data P, wherein said combining is arranged so that the amount of data D and the authentication key K are obtainable using the characteristic C and the storage data P; generating a signature using a signature key, the signature being a digital signature of a quantity of data comprising the storage data P, the amount of data D and the authentication key K, wherein the signature key corresponds to a verification key accessible by the device; generating an authentication code for the error correction data R using the authentication key K, wherein the authenticity of the error correction dat

Abstract: A cryptographic method comprising sequentially performing a number of rounds, each round comprising performing a respective round function on respective input data for that round to generate respective output data for that round, wherein for each of the second and subsequent rounds, the input data for that round is the output data of the preceding round, wherein for each round the respective round function comprises: applying a respective bijective operation to a first amount of data to produce a first result, the bijective operation corresponding to at least part of a cryptographic key; and processing a second amount of data by applying a plurality of processing operations to produce a second result, wherein at least one of the processing operations is the bijective operation; wherein the first amount of data and the second amount of data are based on the input for said round and wherein the output data for said round is based on the first result and the second result; wherein one or both of the following ap

Abstract: An electronics device comprising one or more modules that implement a security-related operation in an obfuscated manner to thereby provide the security-related operation with resistance against a hardware attack, wherein the electronics device is either (a) a printed electronics device or (b) a device created using e-beam lithography.

Abstract: A fingerprinting method. For each round in a series of rounds: providing to each receiver in a set of receivers a version of a source item of content, the source item of content corresponding to the round. For the round there is a corresponding part of a fingerprint-code for the receiver, the part includes one or more symbols. The version provided to the receiver represents those one or more symbols. One or more corresponding symbols are obtained from a suspect item as a corresponding part of a suspect-code. For each receiver in the set of receivers, a corresponding score that indicates a likelihood that the receiver is a colluding-receiver is updated.

Abstract: A method of storing an amount of data D in association with a device, the method comprising: obtaining a characteristic C of the device; generating error correction data R for the characteristic C, the error correction data R enabling correction of up to a predetermined number of errors in a version of the characteristic C; combining the characteristic C with the amount of data D and an authentication key K to generate storage data P, wherein said combining is arranged so that the amount of data D and the authentication key K are obtainable using the characteristic C and the storage data P; generating a signature using a signature key, the signature being a digital signature of a quantity of data comprising the storage data P, the amount of data D and the authentication key K, wherein the signature key corresponds to a verification key accessible by the device; generating an authentication code for the error correction data R using the authentication key K, wherein the authenticity of the error correction dat

Abstract: There is described a method of distributing a first piece of content to multiple receivers. The first piece of content comprises a plurality of content portions. The method comprises: (a) for each of a plurality of selected content portion of the plurality of content portions, there being two or more versions of each said selected content portion, allocating each version of that selected content portion to a respective multicast channel; and (b) providing each receiver with access to a respective group of the multicast channels, each receiver being identifiable at least in part by means of the respective group of multicast channels for that receiver. A corresponding multicast system and receiver are also described.

Abstract: A fingerprinting method. For each round in a series of rounds: providing to each receiver in a set of receivers a version of a source item of content, the source item of content corresponding to the round. For the round there is a corresponding part of a fingerprint-code for the receiver, the part includes one or more symbols. The version provided to the receiver represents those one or more symbols. One or more corresponding symbols are obtained from a suspect item as a corresponding part of a suspect-code. For each receiver in the set of receivers, a corresponding score that indicates a likelihood that the receiver is a colluding-receiver is updated.

Abstract: Method of and device for querying of protected data structured in the form of a tree. A corresponding tree of node polynomials is constructed such that each node polynomial evaluates to zero for an input equal to an identifier assigned to a node name occurring in a branch of the data tree starting with the node in question. A tree of blinding polynomials and a tree of difference polynomials are constructed such that each polynomial in the tree of node polynomials equals the sum of the corresponding polynomial in the tree of blinding polynomials and the corresponding polynomial in the tree of difference polynomials. The blinding tree is given to a client, the difference tree to a server. By combining the outcomes of the evaluations of the client and the server, it is possible to identify nodes that match a given query.