ANALYSIS OF CRYPTOGRAPHIC KEY EXCHANGE ALGORITHMS AND THEIR SECURITY PROBLEMS
Abstract
Cryptographic key exchange protocols are foundational to secure digital communication, enabling two parties to establish shared secrets over untrusted networks. This paper presents a comprehensive analysis of classical (pre-quantum) key exchange algorithms—specifically Diffie–Hellman (DH), Elliptic Curve Diffie–Hellman (ECDH), and RSA-based key transport—focusing on their theoretical security foundations, implementation practices, and real-world vulnerabilities. Drawing on research from 2020 to 2025, we examine how these protocols function under standard assumptions such as the hardness of the discrete logarithm and integer factorization problems, and we analyze a range of attack vectors including man-in-the-middle, padding oracles, side-channel leakage, and fault-based exploits. Our findings highlight the cryptographic and practical superiority of ephemeral ECDH, which offers forward secrecy and robust resistance to modern threats. In contrast, RSA key exchange, while once dominant, is now largely deprecated due to inherent limitations like the lack of forward secrecy and susceptibility to Bleichenbacher-style attacks. We also review mitigation strategies—such as authenticated exchanges, input validation, constant-time implementations, and parameter hardening—and discuss their adoption in standards like TLS 1.3. The paper concludes that while classical key exchange remains secure against conventional adversaries when correctly implemented, continuous vigilance and adherence to best practices are essential. These insights serve to inform protocol designers and implementers navigating the transition to post-quantum cryptography while maintaining strong interim security.
References
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