Randomized RSA Exponentiation for Side-Channel Attack Resistance

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Solution Overview

Problem

Existing electronic communication systems face challenges in securing information from side-channel attacks, such as power analysis and fault attacks, which can compromise private keys and data integrity, especially on portable devices like smart cards and cellular phones.

Innovation Solution

A cryptographic component employing a randomized exponentiation method using a right-to-left square-and-multiply algorithm and the Chinese Remainder Theorem (CRT) with RSA cryptography, which generates a random number to randomize message data during exponentiation and performs a results value check to ensure error-free calculations, thereby securing data from both side-channel and fault attacks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional RSA exponentiation is used, then computational efficiency is maintained, but the system becomes vulnerable to side-channel attacks and fault attacks

Engineering Contradiction:
Improvesecurity against side-channel and fault attacksVSAvoidcryptographic process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by generating a random number and modifying the message data before the exponentiation process begins. This pre-processing step embeds randomness into the cryptographic operation, ensuring that each execution follows a different computational path even for the same input, thereby preventing attackers from correlating power consumption patterns with the exponent bits.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter of the message data by modifying it with a random number before exponentiation. This parameter transformation ensures that the actual value being exponentiated differs from the original message, obscuring the relationship between power consumption and the secret exponent while maintaining the correctness of the final cryptographic result.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If message data is randomized during exponentiation, then protection against side-channel attacks is improved, but additional computational steps are required

Engineering Contradiction:
Improveprotection against power analysis attacksVSAvoidexponentiation processing speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent introduces an intermediary element - a random number - that mediates between the original message and the exponentiation process. This random number acts as a mask that obscures the power consumption patterns associated with the secret exponent, allowing the system to maintain security without fundamentally changing the exponentiation algorithm itself.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If results value check is performed after exponentiation, then detection of fault attacks is enabled, but processing time increases

Engineering Contradiction:
Improvedetection of fault attacksVSAvoidtime for exponentiation and verification
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements feedback by performing a results value check after exponentiation, where the system verifies whether the computed result is valid. This feedback mechanism allows the system to detect fault attacks that may have corrupted the computation, ensuring that only valid cryptographic operations produce acceptable outputs.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS8139763B2Randomized RSA-based cryptographic exponentiation resistant to side channel and fault attacks
Publication Date: 2012.03.20 INFINEON TECHNOLOGIES AMERICAS CORP
  • US8139763B2 patent drawing
  • US8139763B2 patent drawing
  • US8139763B2 patent drawing

AI summary

Systems and/or methods that facilitate secure electronic communication of data are presented. A cryptographic component facilitates data encryption, data decryption, and/or generation of digital signatures, associated with messages. The cryptographic component includes a randomized exponentiation component that facilitates decryption of data and/or generation of digital signatures by exponentiating exponents associated with messages. A random number is generated and utilized to randomize the value of a message. After an exponentiation is performed on the randomized message value, intermediate results can be analyzed to determine if there was error in the exponentiation. If there was no error in the exponentiation, a final value of the exponentiation is determined and provided as output as decrypted data or a digital signature; if there is error, an “error” output can be provided.