Method And Device For Securing Block Ciphers Against Template Attacks
First Claim
1. A method for securing a block cipher (F), encrypted with a working key (K0), against template attacks, the method comprising:
- a) providing a working permutation (F(K0)) fixed by the block cipher (F) and the working key (K0),b) providing a number N of dummy permutations (G(K1), . . . , (G(Kn)) that are fixed by N dummy keys (K1, . . . , Kn) and the block cipher (F) or an inverse (F−
1) of the block cipher (F), andc) chaining the working permutation (F(K0)) and the dummy permutations (G(K1), . . . , (G(Kn)) to form a chain such that the chain and the working permutation (F(K0)) produce an identical image.
1 Assignment
0 Petitions
Accused Products
Abstract
A method for securing a block cipher F, encrypted with a working key K0, against template attacks is provided. A working permutation F(K0) fixed by the block cipher F and the working key K0, and a number N of dummy permutations G(K1), . . . , G(Kn) are provided. The N dummy permutations G(K1), . . . , G(Kn) are fixed by N dummy keys K1, . . . , Kn and the block cipher F or the inverse F−1 of the block cipher F. The working permutation F(K0) and the N dummy permutations G(K1), . . . , (G(Kn) are chained to form a chain H in such a way that the chain H and the working permutation F(K0) produce an identical image (H=F(K0)). A block cipher F, in which a fixed key K0 is used, is protected against template attacks as a result. A computer program product and a device for securing a block cipher F against template attacks are also proposed.
26 Citations
18 Claims
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1. A method for securing a block cipher (F), encrypted with a working key (K0), against template attacks, the method comprising:
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a) providing a working permutation (F(K0)) fixed by the block cipher (F) and the working key (K0), b) providing a number N of dummy permutations (G(K1), . . . , (G(Kn)) that are fixed by N dummy keys (K1, . . . , Kn) and the block cipher (F) or an inverse (F−
1) of the block cipher (F), andc) chaining the working permutation (F(K0)) and the dummy permutations (G(K1), . . . , (G(Kn)) to form a chain such that the chain and the working permutation (F(K0)) produce an identical image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A computer program product for securing a block cipher (F), encrypted with a working key (K0), against template attacks, the computer program product being embodied in non-transitory computer readable media and executable by a processor to:
- provide a working permutation (F(K0)) fixed by the block cipher (F) and the working key (Kd0),
provide a number N of dummy permutations (G(K1), . . . , (G(Kn)) that are fixed by N dummy keys (K1, . . . , Kn) and the block cipher (F) or an inverse (F−
1) of the block cipher (F), andchain the working permutation (F(K0)) and the dummy permutations (G(K1), . . . , (G(Kn)) to form a chain such that the chain and the working permutation (F(K0)) produce an identical image. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
- provide a working permutation (F(K0)) fixed by the block cipher (F) and the working key (Kd0),
Specification