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Cryptographic method for a white-box implementation

An encryption method, white box technology, applied in encryption devices with shift registers/memory, countermeasures to attack encryption mechanisms, digital transmission systems, etc.

Inactive Publication Date: 2009-09-16
IRDETO ACCESS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First, the reverse design of the certificate database access function can lead to black box software (that is, the attacker does not have to understand the inner working of the software function), so that the attacker can obtain the asset key (asset key) from all certificate databases

Method used

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  • Cryptographic method for a white-box implementation
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  • Cryptographic method for a white-box implementation

Examples

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Embodiment Construction

[0046] AES is a block cipher with a block size of 128 bits or 16 bytes. The plaintext is divided into 16-byte blocks that form the initial state of the encoding algorithm, the final state of which is the ciphertext. To explain AES conceptually, the status bits are organized as a matrix of 4x4 bytes. AES consists of multiple rounds. Each round consists of similar processing steps operating on the bytes, rows, or columns of the state matrix, and each round uses a different round key during these processings.

[0047] figure 1 Some main processing steps of an AES round are illustrated. These processing steps include:

[0048] - Add RoundKey (AddRoundKey)2 - each byte of this state is exclusive-ored (XORed) with the byte of the round key.

[0049] -SubBytes 4 - byte-by-byte permutation using a lookup table.

[0050] - Shift Rows (ShiftRows) 6 - Each row of state is cycled by a fixed number of bits.

[0051] - MixColumns (MixColumns) 8 - use GF(2 8 ) to process each column....

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Abstract

A cryptographic method is implemented in a white -box implementation thereof. The method comprises applying a plurality of transformations (802) each replacing an input word by an output word, and applying a diffusion operator (804) to a concatenation of a plurality of the output words for diffusing information represented by the output words among the output words. A key (806) to the cryptographic method comprises information representing the diffusion operator. The diffusion operator satisfies a property that a change of one bit in an input to the diffusion operator corresponds to a change of more than one bit in an output of the diffusion operator.

Description

technical field [0001] The present invention relates to an encryption method implemented in a white-box implementation. Background technique [0002] The Internet provides users with convenient, ubiquitous access to digital content. The use of the Internet as a distribution medium for copyrighted content raises compelling difficulties in protecting the interests of content providers. In particular, it is required to guarantee the copyright and business model of the content provider. Increasingly, consumer electronics (CE) platforms are operating on processors loaded with appropriate software. Such software may include a substantial portion of the functionality for reproducing (playing back) electronic content such as audio and / or video. Controlling playback software, including the terms and conditions under which content can be used, is one way to enhance the interests of content owners. Where traditionally many CE platforms (except for PCs and PDAs) were closed, more an...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L9/06
CPCH04L9/0681H04L9/0631H04L9/002H04L9/0612H04L2209/16
Inventor W·P·A·J·米基尔斯P·M·H·M·A·格里森
Owner IRDETO ACCESS