White-box cryptographic keys
AssigneeBanks and Acquirers International Holding
InventorVincent GIRAUD
Life of this patent
Estimating the term…
Abstract
A method for generating a cryptographic key, which is executed by a computer processor, wherein steps of generating matrices in accordance with a McEliece cryptosystem are carried out. The computer processor then further executes at least two of the following three combination steps: combining one random encoding matrix with the merged permutation, coding and transformation matrix to form an encoded permutation, coding and transformation matrix; combining another random encoding matrix with the permutation cancellation matrix to form an encoded permutation cancellation matrix; and combining another random encoding matrix with the transformation cancellation matrix to form an encoded transformation cancellation matrix.
Claims18
A method for generating a cryptographic key, executed by computer processing means, wherein the following steps are carried out:
- generating a permutation matrix (P), a coding matrix (G) and a linear transformation matrix (S), the three matrices being in accordance with a McEliece cryptosystem;
- generating an inverse permutation cancellation matrix (P−1) of the permutation matrix (P), an inverse coding cancellation matrix (G−1) of the coding matrix (G), and an inverse transformation cancellation matrix (S−1) of the linear transformation matrix (S), the three cancellation matrices (S−1, G−1, P−1) being in accordance with the McEliece cryptosystem;
- combining the permutation matrix (P) with the coding matrix (G) and with the linear transformation matrix (S), to form a merged permutation, coding and transformation matrix (SGP) in accordance with the McEliece cryptosystem, characterised in that the computer processing means execute a step of generating at least two random encoding matrices (J−1, F−1, H), the computer processing means executing at least two of the following three combinations steps:
- combining one of the random encoding matrices (J−1) with the merged permutation, coding and transformation matrix (SGP), to form an encoded permutation, coding and transformation matrix (J−1SGP),
- combining another one of the random encoding matrices (F−1) with the permutation cancellation matrix (P−1) to form an encoded permutation cancellation matrix (F−1P−1),
- combining another one of the random encoding matrices (H) with the transformation cancellation matrix (S−1) to form an encoded transformation cancellation matrix (S−1H).
A data encryption method, characterised in that, to encrypt a data series, computer processing means execute the following steps:
- after a merged transformation, coding and permutation matrix (SGP), in accordance with a McEliece cryptosystem, has been combined with an encoding matrix (J−1) to form an encoded coding, permutation and transformation matrix (J−1SGP), applying the encoded coding, permutation and transformation matrix (J−1SGP) to the data series, in order to form a coded, permuted and transformed data series;
- deliberately adding one or more errors, in accordance with the McEliece cryptosystem, to the coded permuted and transformed data series, in order to form an encrypted data series.
A data decryption method, characterised in that, to decrypt an encrypted data series, a permutation cancellation matrix (P−1), in accordance with a McEliece cryptosystem, having been combined with an inverse encoding cancellation matrix (F−1) of an encoding matrix (F), previously applied during an encryption operation, to form an encoded permutation cancellation matrix (F−1P−1), a processing means execute a step of applying to the encrypted data series the encoded permutation cancellation matrix (F−1P−1) to form a restructured data series with cancelled encoding.
Dependencies are inferred from the claim text.