Security Analysis of Context-Bound Parallel Post-Quantum Authentication for Blockchain Transactions Using Hybrid Signatures

The advancement of quantum computing poses a serious threat to conventional public key cryptography, as quantum algorithms could undermine the underlying mathematical problems used for security, potentially exposing private keys, enabling fraudulent digital signatures and unauthorized transactions, and compromising the confidentiality and integrity of protected data. The cryptographic mechanism plays a major role in achieving guaranteed ledger integrity and validity of a transaction in a blockchain. Nevertheless, commonly deployed signature schemes such as RSA, DSA, and ECDSA are susceptible to quantum-enabled attacks. We assess the viability of several quantum-safe cryptographic techniques for blockchain applications, including lattice-based, hash-based, and multivariate polynomial cryptography. Leading digital signature algorithms such as the Fourier-Lattice-Based Digital Signature Algorithm (Falcon), Module-Lattice-Based Digital Signature Algorithm (ML-DSA), Stateless Hash-Based Digital Signature Algorithm (SLH-DSA), and Module-Lattice-Based Key-Encapsulation Mechanism (ML-KEM) achieve strong security. However, existing multi-signature approaches focus on combining traditional cryptographic algorithms and post-quantum cryptographic algorithms to achieve security. This study evaluates Falcon-512 and ML-DSA-65 as two independent post-quantum signature components and combines them into a hybrid parallel dual-signature construction for blockchain-oriented transaction authentication. RSA-2048 and ECDSA P-256 are retained as classical reference schemes. The work has two distinct levels. The first is an empirical engineering study of key generation, signing, verification, transaction latency, throughput, signature size, storage, CPU usage, memory usage, tampering detection, and cross-scheme consistency. The second is a security extension motivated by a limitation of hybrid composition. Across the evaluated workloads, Falcon-512 achieved a throughput of approximately 283.88–290.28 transactions per second, whereas the parallel dual-signature construction achieved approximately 16.97–18.99 transactions per second. In the evaluated configurations, context-bound verification achieved zero cross-context acceptance and a 100% cross-context isolation rate. These findings demonstrate the importance of binding signatures to an explicitly defined security context and enforcing verification of both signature components. The security results provide a clearer distinction between legitimate and malicious transactions.