Abstract: A device and method for processing a ciphertext, including determining a seed using a secret key and the ciphertext, extracting a public key candidate from the ciphertext using the seed, determining a checkvalue candidate based on the public key candidate, comparing the checkvalue candidate with a checkvalue, and further processing the ciphertext if the comparison indicates that the checkvalue candidate corresponds to the checkvalue.

Abstract: According to an embodiment, a data processing device is described comprising a deformer configured to deform a first data block in accordance with a first seed, a seed generator configured to generate a sequence of second seeds, wherein the sequence of second seeds comprises the first seed, a cryptographic processor configured to receive the deformed first data block and, for each second seed, to deform the deformed first data block in accordance with the second seed, to generate a sequence of second data blocks and to cryptographically process each second data block of the sequence of second data blocks to generate a sequence of processed data blocks and an extractor configured to extract a result of the cryptographic processing of the first data block from the sequence of processed data blocks.

Abstract: A method for executing a cryptographic operation is provided comprising acts comprising: (i) sampling a first polynomial, wherein one or more (e.g., one, some and/or all) coefficients of the first polynomial are determined; (ii) sampling a second polynomial, wherein a selection of k coefficients of the second polynomial is determined; (iii) multiplying the first polynomial with the second polynomial to determine a result; and (iv) using the result of the multiplication in the cryptographic operation. A security device arranged to perform one, some and/or all of the acts is provided.

Abstract: According to one embodiment, an execution unit is described, which includes a mask generation circuit configured to generate a mask by multiplying a mask generation vector by blocks of codewords of a plurality of cyclic codes, a masking circuit configured to mask data to be processed by means of the mask, and an arithmetic logic unit configured to process the masked data by means of additions and rotations.

Abstract: In various embodiments, a method for performing a lattice-based cryptographic operation is provided. The method includes obtaining a noise polynomial, a secret polynomial and a public polynomial, disguising at least one of the noise polynomial, the secret polynomial and the public polynomial by means of multiplying it with a random blinding polynomial, calculating the sum of the noise polynomial with the product of the public polynomial and the secret polynomial based on the disguised at least one polynomial, and determining a result of the lattice-based cryptographic operation based on the calculated sum of the noise polynomial with the product of the public polynomial and the secret polynomial.

Abstract: A method for checking results, including (a) determining a first result by conducting an operation g( ) based on test data; (b) determining combined data by performing a combining operation based on the test data and user data; (c) determining a second result conducting the operation g( ) based on the combined data; and (d) determining whether the second result is indicative of the first result.

Abstract: A method for conducting an operation including (a) lifting coefficients of a data structure from a representation modulo q to a representation modulo q?, wherein the data structure comprises values which are reduced modulo q, wherein q and are integers; (b) randomizing the coefficients in modulo q?, wherein for each coefficient a random value is multiplied with the value of q and the result of this multiplication is added to the coefficient; (c) conducting an operation on the lifted and randomized coefficients; and (d) reducing the lifted and randomized coefficients by conducting an operation modulo q.

Abstract: According to an embodiment, a data processing device is described comprising a deformer configured to deform a first data block in accordance with a first seed, a seed generator configured to generate a sequence of second seeds, wherein the sequence of second seeds comprises the first seed, a cryptographic processor configured to receive the deformed first data block and, for each second seed, to deform the deformed first data block in accordance with the second seed, to generate a sequence of second data blocks and to cryptographically process each second data block of the sequence of second data blocks to generate a sequence of processed data blocks and an extractor configured to extract a result of the cryptographic processing of the first data block from the sequence of processed data blocks.