Per-Transaction Key Derivation for Secure Terminal Authentication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing Derive Unique Key Per Transaction (DUKPT) method, as defined in ANSI standard X9.24-3, faces challenges in managing unique symmetric cryptographic keys for transaction processing services, particularly in older terminals where initial key replacement is problematic and requires manual procedures or asymmetric key exchange, limiting scalability and security.
Innovation Solution
The method involves deriving a unique random cryptographic key per transaction using an initial key and a randomly generated number, with the device encrypting original data and sending it to a host, which can then decrypt and verify it using a host-derived key, eliminating the need for key storage aside from a base key and avoiding asymmetric cryptography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional DUKPT method is used with transaction counter, then key management is simplified, but key replacement becomes problematic in older terminals
Solution Approach 1:
The system pre-generates a pool of unique random keys and stores them in the terminal before deployment. These keys are prepared in advance and can be used immediately when needed, eliminating the need for complex key replacement procedures in older terminals that cannot support transaction counters or asymmetric cryptography.
Solution Approach 2:
The patent uses disposable single-use keys from a pre-generated pool. Each key is used once for a single transaction and then discarded, replacing the traditional model where keys need to be reused and managed over long periods. This approach simplifies key replacement since new keys are simply drawn from the pre-generated pool.
2Reliability
If manual procedures or asymmetric key exchange is used for key replacement, then security is maintained, but scalability is limited
Solution Approach 1:
The terminal autonomously selects and uses keys from its pre-generated pool without requiring external key management infrastructure. The terminal can independently perform key selection, encryption, and transaction processing, eliminating the need for manual key distribution or asymmetric key exchange protocols, thereby enabling scalable deployment.
Solution Approach 2:
All necessary cryptographic keys are generated and loaded into the terminal during initial provisioning or key injection phases. This preliminary key generation eliminates the need for ongoing key management operations during normal transaction processing, allowing the system to scale without proportionally increasing key management overhead.
3Reliability
If unique symmetric cryptographic key per transaction is implemented, then security is enhanced, but key management complexity increases
Solution Approach 1:
The system generates a large pool of unique random keys in advance and stores them in the terminal's secure memory. This preliminary key generation transforms the complexity from runtime key derivation to initial key provisioning, simplifying the operational complexity during actual transactions while maintaining the security benefit of unique per-transaction keys.
Solution Approach 2:
The patent implements a pool of disposable single-use keys that are pre-generated and stored in the terminal. Each key is used once and then discarded, eliminating the need for complex key derivation algorithms or key rotation mechanisms. The terminal simply selects the next available key from the pool, dramatically reducing key management complexity while maintaining strong security.
Data Source
AI summary
In one arrangement, a method for using symmetric keys between two entities comprising a device and a host include initiating, by the device, a transaction involving original data, wherein the original data needs to be verified by the host. The method further includes deriving, by the device, a first key based on a previously generated key and a first number, wherein the first key is unique to the transaction, and the first number is randomly generated. The method further includes sending, by the device, the first key to the host for verification.