Why a cryptographic inventory is key for addressing the quantum computing threat

August 28, 2026 · Tenable Blog · Severity: CRITICAL

When quantum computers become generally available, they’ll be able to crack current public-key cryptographic algorithms, putting digitally stored and transmitted data at risk. But the threat already exists, as attackers use the "harvest now, decrypt later" tactic. Discover why building a comprehensive cryptographic inventory and executing a phased operational strategy are critical for protecting your data against quantum computing attacks.Key takeawaysQuantum computing risks are an operational threat today due to "harvest now, decrypt later" (HNDL) tactics, in which adversaries actively harvest and store encrypted data to decrypt it retroactively once quantum capabilities mature.When run on a quantum computer that’s powerful enough, Shor’s Algorithm will break foundational asymmetric infrastructure like the RSA, ECC, and Diffie-Hellman algorithms, although symmetric encryption standards like AES-256 are expected to remain secure against quantum attacks.Globally, more regulatory bodies are starting to mandate a comprehensive cryptographic inventory, making absolute visibility across the digital environment a prerequisite for an orderly post-quantum migration.Transitioning to quantum-resistant cryptography requires a phased operational strategy spanning discovery, prioritization, remediation, and verification.The quantum threat to modern security architectureFuture quantum computers will represent a threat to the foundational security architecture that protects digital data. For decades, the global economy, national security apparatus, and critical infrastructure have relied on asymmetric cryptography, specifically RSA and elliptic curve cryptography (ECC), to secure data in transit, authenticate identities, and protect digital signatures. The mathematical difficulty of factoring large integers or solving discrete logarithm problems has long provided a robust shield against cyber attacks launched using conventional computing capabilities.However, the rapid...