Securing against Quantum: An Executive Summary

Quantum computing is an emerging technology with great promise accompanied by very real threats to cybersecurity. In this article we will explain the threats and steps to safely navigate the post-quantum era.

DISCLAIMER: This information is provided for educational and informational purposes only. By using this material, you acknowledge and agree to assume full responsibility for the risks and damages that may arise from your actions. HiDi Corporation is not responsible or liable for any errors, omissions, or outcomes from the use of this information. Please consult HiDi Corporation directly for professional advice on your cryptographic security needs.

Cryptography is a necessary tool for securing computers and data, both in the context of physical access and cybersecurity. The security of cryptographic schemes is built around computational problems that are extremely difficult for even the largest supercomputers to solve.

The 4 Cryptography Tasks

Cryptography has 4 core tasks: confidentiality, integrity, authentication, and non-repudiation.

Confidentiality

Integrity

Protect data from unauthorized access

Detect data tampering or corruption

Authentication

Non-repudiation

Verify the identity of an entity

Authenticated proof of an action/transaction

The 3 Cryptography Primitives

The 4 cryptographic tasks mentioned above can be carried out through a combination of three primitives: hash functions, symmetric encryption, and asymmetric encryption. The table below summarizes their operations, standard algorithms, useful features, what makes them secure, and their level of vulnerability to quantum computers.

A hashing algorithm will process arbitrary data into a hash. It is computationally infeasible to generate data with an identical hash.

Symmetric key encryption uses the same key to encrypt and decrypt data.

Asymmetric encryption uses separate keys for encryption and decryption.

	Hash Functions	Symmetric Key Encryption	Asymmetric Key Encryption
Keys	No keys	One secret key	Two keys: public and private
Algorithm	Compute a fixed-length hash string from arbitrary data	Encrypt-decrypt data between plaintext-ciphertext with a key	Establish security between two entities without a predetermined key
Useful Feature	Computation of the hash string is repeatable	Ciphertext bears no resemblance to plaintext	Various schemes to encrypt/decrypt, sign, or verify data
Security	Generating data to match a bitstring is infeasible	Guessing the key from plaintext and corresponding ciphertext is infeasible	Decrypting or signing data without the private key is infeasible
Quantum Vulnerability	Low	Low	High

The tasks and primitives are covered in detail in our tutorial on breaking cryptography using quantum computers.

Vulnerabilities

All three primitives are vulnerable to attack from quantum computers. Fortunately, the threat to hashing and symmetric cryptography is relatively benign with simple fixes. On the other hand, asymmetric encryption requires a complete overhaul of the encryption algorithms. Establishing secure connections is the most common application of asymmetric encryption.

Adversaries are already intercepting and archiving encrypted communications, intellectual property, and financial records to harvest now, decrypt later.. Once fault-tolerant quantum systems reach operational scale, this stored data will be vulnerable. The encryption protecting your data today may not protect it once large-scale fault-tolerant quantum computers are available.

Strategic Action Plan

Cryptographic Asset Inventory
Perform a top-down inventory of all cybersecurity elements in your organization. Document all certificates, key stores, legacy systems, and third-party dependencies. Identify where RSA/ECC encryption is still in use.
PQC Migration Rollout
Begin transitioning to post-quantum cryptography (PQC) standards: NIST FIPS 203/204/205 for key exchange and digital signatures. Plan hybrid deployments during the transition window.
Upgrade Symmetric & Hash Parameters
Implement AES-256 and SHA-512 across high-security environments, cloud workloads, and long-retention data pipelines.
Strengthen Cryptographic Randomness
For high security applications consider replacing deterministic software-based pseudo-random number generators (PRNGs) with hardware-based Quantum Random Number Generators (QRNG) to eliminate seeding predictability.
Monitor QKD Infrastructure
Appropriate resources to prepare for integration with quantum networks, and an eventual transition to quantum key distribution (QKD). Evaluate quantum network readiness for future hybrid security models.

Quantum readiness is a multi-year engineering and governance challenge. Firmware updates, certificate rotation, supply chain coordination, and legacy system decommissioning must be carefully rolled out and warrant a long transition period.

For a technical deep dive into how Shor’s and Grover’s algorithms break classical cryptography, see our companion tutorial: Breaking Cryptography with Quantum Computers: A Tutorial.