Signature Generation Apparatus Preventing Transcript Attacks
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Solution Overview
Problem
The NTRUSign signature scheme is vulnerable to transcript attacks, which recover the private key from multiple signed texts, requiring a large number of signatures to successfully attack, posing a security risk.
Innovation Solution
A signature generation and verification apparatus that counts cumulative digital signature operations and inhibits the use of the signature key when a predetermined count is reached, either by inhibiting the key's use or generating a new key to prevent key exposure, thereby preventing transcript attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the NTRUSign signature scheme is used for digital signature operations, then high-speed processing is achieved, but the system becomes vulnerable to transcript attacks that recover private keys from multiple signatures
Solution Approach 1:
The patent applies preliminary action by establishing a signature count limit before the security breach can occur. The system pre-determines a maximum number of signatures that can be generated with a single key pair, and automatically stops signature operations or generates new key pairs when this limit is reached, preventing the accumulation of enough signatures for transcript attacks to succeed.
Solution Approach 2:
The patent implements dynamics by making the signature key pair lifecycle dynamic rather than static. The system continuously monitors the number of signatures generated and automatically updates or invalidates key pairs based on usage patterns, adapting the security parameters in real-time to maintain protection against transcript attacks while enabling high-speed operation.
2Productivity
If multiple signatures are generated with a single key pair to increase productivity, then the system becomes susceptible to transcript attacks
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the effective lifespan and usage limits of cryptographic key pairs. The system changes the operational parameters of signature generation by imposing count-based restrictions and automatically rotating key pairs, thereby controlling the total number of signatures that can be produced with any single key pair to remain below the threshold required for successful transcript attacks.
3Ease of operation
If the signature key is reused for multiple operations to simplify key management, then security is compromised due to transcript attack risks
Solution Approach 1:
The patent applies segmentation by dividing the signature generation process into multiple isolated key pair instances rather than using a single long-lived key pair. The system automatically creates, manages, and rotates multiple short-lived key pairs, each valid for a limited number of signatures, thereby segmenting the overall signature operation into secure, isolated units that prevent transcript attacks while maintaining operational simplicity through automated key management.
Data Source
AI summary
A signature generation apparatus capable of preventing transcript attack on signature data is provided. The signature generation apparatus performing a digital signature operation with the use of a signature key: stores the signature key; performs the digital signature operation on signature target data with the use of the signature key to generate signature data; counts the cumulative count of digital signature operations having been performed by the signature generation unit with the use of the signature key; judges whether the cumulative count has reached a predetermined count; and inhibits the use of the signature key in the digital signature operation from then onward in a case where the judgment unit determines that the cumulative count has reached the predetermined count.