Nonlinear feedback mode for block ciphers
AssigneeRed Hat, Inc.
InventorJames P. Schneider
Life of this patent
Estimating the term…
Abstract
Plain text, a secret key and a primitive polynomial that defines a finite field of even characteristic are received. The plain text is divided into a plurality of plain text blocks. For each plain text block of the plurality of plain text blocks other than a first plain text block, the plain text block is multiplied by a preceding cipher text block over the finite field of even characteristic, modulo the primitive polynomial, to generate an intermediate block, wherein the preceding cipher text block was generated from a preceding plain text block. Each intermediate block is processed by a block cipher using the secret key to generate a subsequent cipher text block. The block cipher operates in a nonlinear feedback mode of operation.
Claims30
A method of securing data, comprising:
- receiving plain text, a secret key and a primitive polynomial that defines a finite field of even characteristic;
- dividing the plain text into a plurality of plain text blocks;
- and
- for each plain text block of the plurality of plain text blocks other than a first plain text block:
- multiplying the plain text block by a preceding cipher text block over the finite field of even characteristic, modulo the primitive polynomial, to generate an intermediate block, wherein the preceding cipher text block was generated from a preceding plain text block;
- and
- processing the intermediate block by a block cipher using the secret key to generate a subsequent cipher text block, wherein the block cipher operates in a nonlinear feedback mode of operation.
A method of securing data, comprising:
- receiving plain text and a secret key by a block cipher;
- dividing the plain text into a plurality of plain text blocks;
- and
- for each plain text block of the plurality of plain text blocks other than a first plain text block:
- receiving a secret bit sequence;
- rotating at least one of the plain text block or a preceding cipher text block by a number of bits based on the secret bit sequence;
- performing a mathematical operation combining the plain text block with the preceding cipher text block to generate an intermediate block;
- and
- processing the intermediate block by a block cipher using the secret key to generate a subsequent cipher text block, wherein the block cipher operates in a nonlinear feedback mode of operation.
A computer readable medium including instructions that, when executed by a processing system, cause the processing system to perform a method of securing data, comprising:
- receiving plain text, a secret key and a primitive polynomial that defines a finite field of even characteristic;
- dividing the plain text into a plurality of plain text blocks;
- and
- for each plain text block of the plurality of plain text blocks other than a first plain text block:
- multiplying the plain text block by a preceding cipher text block over the finite field of even characteristic, modulo the primitive polynomial, to generate an intermediate block, wherein the preceding cipher text block was generated from a preceding plain text block;
- and
- processing the intermediate block by a block cipher using the secret key to generate a subsequent cipher text block, wherein the block cipher operates in a nonlinear feedback mode of operation.
A computer readable medium including instructions that, when executed by a processing system, cause the processing system to perform a method of securing data, comprising:
- receiving plain text and a secret key by a block cipher;
- dividing the plain text into a plurality of plain text blocks;
- and
- for each plain text block of the plurality of plain text blocks other than a first plain text block:
- receiving a secret bit sequence;
- rotating at least one of the plain text block or a preceding cipher text block by a number of bits based on the secret bit sequence;
- performing a mathematical operation combining the plain text block with the preceding cipher text block to generate an intermediate block;
- and
- processing the intermediate block by a block cipher using the secret key to generate a subsequent cipher text block, wherein the block cipher operates in a nonlinear feedback mode of operation.
A block cipher encryption system comprising:
- a combiner logic component configured to receive a primitive polynomial that defines a finite field of even characteristic and, at each of a plurality of rounds of encryption other than a first round of encryption, to receive a plain text block, to receive a preceding cipher text block that was generated from a preceding plain text block, to multiply the plain text block by the preceding cipher text block over the finite field of even characteristic, modulo the primitive polynomial to generate an intermediate block, and to provide the intermediate block to a block cipher;
- and
- the block cipher, coupled to the combiner logic component, configured to receive a secret key and, at each of the plurality of rounds of encryption, to receive the intermediate block, and to process the intermediate block using the secret key to generate a subsequent cipher text block, wherein the block cipher operates in a nonlinear feedback mode of operation.
Dependencies are inferred from the claim text.