Signature Generation Device 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 signed texts to succeed, posing a significant security risk.
Innovation Solution
A signature generation apparatus that acquires a private key different from the one used in previous digital signature operations, either randomly or through a predetermined method, to prevent transcript attacks by ensuring the attacker cannot determine which private key was used for the signature data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the NTRUSign signature scheme uses a single private key for digital signature operations, then the processing speed and implementation simplicity are improved, but the system becomes vulnerable to transcript attacks where the private key can be recovered from multiple signed texts
Solution Approach 1:
The patent segments the single private key into multiple private keys (first private key and second private key) that correspond to the same public key. This segmentation allows the system to switch between different private keys for different signature operations, preventing an attacker from recovering a single private key through transcript attacks while maintaining the same public key for verification. The segmentation directly resolves the security vulnerability without sacrificing processing speed.
Solution Approach 2:
The patent introduces dynamic key selection by randomly choosing between the first private key and second private key for each digital signature operation. This dynamic approach ensures that even if multiple signatures are obtained, an attacker cannot determine which private key was used for each signature, thereby preventing transcript attacks. The randomness and dynamic selection maintain implementation simplicity while enhancing security.
2Reliability
If multiple private keys are generated and stored to prevent transcript attacks, then the security against transcript attacks is improved, but the device complexity and key management overhead increase
Solution Approach 1:
The patent makes both the first private key and second private key correspond to the same public key, enabling both keys to perform the same function of generating valid signatures. This multi-functionality allows the system to use multiple private keys without requiring multiple public keys or complex key management infrastructure. The universal correspondence simplifies key management while providing security against transcript attacks.
Solution Approach 2:
The patent changes the parameter of private key identity by generating multiple private keys that are mathematically equivalent in terms of their corresponding public key but differ in their internal structure. This parameter change allows the system to vary the private key used for each operation while maintaining compatibility with the same public key, thereby preventing transcript attacks without increasing device complexity.
3Reliability
If a random private key selection method is used for each signature operation, then the security against transcript attacks is improved by making it unpredictable which private key is used, but the ease of operation decreases due to additional random selection overhead
Solution Approach 1:
The patent implements self-service by having the signature generation device automatically and randomly select between the first private key and second private key without requiring external intervention or complex decision-making processes. This self-service approach maintains ease of operation while achieving unpredictability, as the random selection is performed autonomously during the signature generation process itself, adding minimal overhead.
Data Source
AI summary
A signature generation apparatus preventing an transcript attack on signature data. The signature generation apparatus for generating signature data for message data (i) acquires, according to a predetermined acquisition method, a private key, which is different from a private key used in a previous digital signature operation, from among a plurality of private keys generated using a key generation method of a signature scheme in which the plurality of private keys correspond to a single public key, and (ii) performs, using the acquired private key, a digital signature operation on the message data according to a signature method of the signature scheme to generate the signature data.