Digital communication, with all its advantages and conveniences, requires a degree of caution where sensitive, private, or proprietary data is concerned. Public key cryptography underpins modern digital security, enabling secure communication, authentication, and encryption at scale. Often, the online trust discussion centers around the security of private keys, and understandably so; however, public keys, whose role is to encrypt data and enable digital signature verification, are just as important in modern cryptography.
Cryptographic algorithms are heavily impacted by emerging security challenges, including quantum security, necessitating constant iteration and adaptation. In the era of post-quantum cryptography (PQC), the changes in algorithms will affect the private and public key generation alike, further emphasizing the importance of crypto-agility in PKI and the enterprise readiness to adopt future-proof encryption strategies.
What Is a Public Key
A public key is a string of cryptographic data designed to be shared openly. Key pairs consisting of public and private keys are the foundation for cryptographic algorithms, with which encrypted data may be exchanged more securely over unsecured networks. Public and private key pairs are used in asymmetric encryption, where one is used to encrypt (public key) and the other to decrypt data (private key). Less commonly used today as a standalone is symmetric encryption, where only one private key is used for both, necessitating the exchange by interested parties beforehand.
How Public Encryption Works
This pairing of private and public keys is fundamental. Only the corresponding private key may decrypt the data encrypted by the public key. While the public key is by definition publicly available, it works to keep data safe together with its paired private key. SSL/TSL certificates that secure website data are a good example of this: they establish a secure connection between a website and a user’s browser, ensuring the data exchanged in the process can only be accessed and processed by the two parties.
In the case of digital signatures, the signature is created using a private key, which can then be verified by the corresponding public key, signalling the authenticity and non-repudiation of the data, asset, or communication that was digitally signed. Public keys, together with private keys, tie into the PKI infrastructure overall, where trusted third parties (certificate authorities) bind public keys to verified identities in the form of digital certificates to establish and maintain trust. Secure email and secure HTTPS connections all make use of digital certificates to keep data confidential, its exchanges protected, and its integrity and identity assured.
Applications of Public Keys in Enterprise Security
The security of digital communications, while important for any entity and individual, is especially critical for large organizations and enterprises. There, PKI and digital certificates become the cornerstone for establishing trusted digital identities. Business continuity, brand reputation, and consumer trust all rest on the security and authenticity of the internal and external environments these enterprises operate.
Integrity of data shared between parties, such as in software supply chains, is critical for trust. Code signing certificates and digital signatures enable recipients to verify the authorship of documents by verifying the digital signature against the public key it corresponds to. In turn, the senders of data can be certain that the code or assets reach the intended end user exactly as intended—encryption helps prevent data tampering and man-in-the-middle attacks.
Protecting data integrity, authenticating its origin, and the identity of its publisher is important not only at a user-to-user level, but with enterprise machine-to-machine communications too, as is the case with sending over-the-air updates to Internet of Things (IoT) devices, powering application programming interfaces (APIs), and delivering microservices. All of these make use of public keys matched with private keys kept confidential, to encrypt data exchange, authenticate users, and validate digital signatures.
Challenges with Public Key Cryptography
Public key infrastructure is a challenging environment to maintain at every level, but key management complexity becomes especially pronounced in large enterprises. The foundational difficulty is in the sheer volume of digital certificates powering PKI that require monitoring and upkeep, from issuance to installation to renewal and revocation.
Depending on the makeup of the IT team or DevOps, key management may be manual, script-based, or tools-based. With the rising volumes, the more hands-on methods run higher risks of certificate misconfiguration and expiration, potentially causing outages and impacting business continuity. If certificates tied to public keys expire, the keys become invalid as well, jumpstarting a cascade of delays.
High-volume environments demand a balance between security and agility, infrastructure investment costs, and system stability. Trading off performance, such as speed of certificate issuance and renewal, for extended validity certificates, longer load times of lengthier public and private keys, may be necessary for a more robust PKI environment that demands cutting-edge cryptography solutions, especially in light of the emerging quantum computing capabilities.
Public Keys and Quantum Security
While no one can say when exactly it will be, the era of quantum computing will render the current industry standards for encryption obsolete. Quantum computing especially threatens the current public key algorithms such as RSA and ECC that rely on key length for increased security. Quantum-resistant encryption algorithms will need to take their place, and enterprises must get ready for this reality today to stay secure and continue reaping the benefits of digital trust.
The concept of crypto-agility becomes crucial for quantum preparedness. Not only does it enable enterprises’ transitioning away from vulnerable algorithms, but it also allows organizations to respond to anything the technological reality throws at them without sacrificing security, performance, or compliance by baking the option to upgrade and change algorithms at will in line with emerging threats. Crypto-agile organizations are the ones who prioritize efficient and effective management and run their PKI program with intention and oversight, often with the help of PKI solutions.
Best Practices for Managing Public Keys
How can an enterprise prepare for post-quantum cryptography and transition to becoming crypto-agile? Start by implementing the best practices of managing public keys, which begins with centralizing all key and digital certificate management across the enterprise. Full cataloguing of PKI components and visibility into their lifecycles is the first step to overcoming the difficulties of managing the certificate volume. Their number isn’t going down; the effort to manage them all can.
Second, enforce strong algorithms, choosing the encryption strength to the maximum of what the organizational resources may withstand. Longer (lengthier) keys take longer to process and validate during digital handshakes, and thus they put more strain on IT resources; the tradeoff is higher security. Rotating keys regularly is a good best practice that lowers the possibility of private keys being lost or compromised, which is their biggest vulnerability. Regularly rotated keys ensure revocation or expiry of certificates doesn’t impact operations for long, even if they slip through the cracks.
Monitoring throughout the certificate lifecycle and setting up alerts should something raise a red flag will prevent outages and lower the impact of potential security breaches, since they will be caught earlier, giving the team more time to respond and mitigate the threats.
To prepare for post-quantum transitions, an organization’s DevOps teams should consider creating a Cryptography Bill of Materials, or CBOM, to fully catalogue not just the cryptographic assets, PKI components, and certificates used in all of the enterprise environments, but also their dependencies, which will paint a full picture for PKI to future-proof and enable the team to start upgrading the cryptography algorithms and the associated policies, SOPs, and training needed to get quantum-ready.
Conclusion
Public keys are a foundational part of public cryptography that are critical for data encryption and the enablement of digital trust. Public keys encrypt the data and enable the verification of their publishers’ identities, helping maintain data integrity, authentication, and security. They will continue to be critical in the era of post-quantum cryptography, albeit the encryption algorithms will look different from how they do today; enterprises must begin their quantum security preparation now, without waiting, otherwise it will be too late by the time PQC arrives. A centralized, organized, intelligently managed, and automated PKI is the bedrock for crypto-agility—to safeguard against tomorrow’s risks, adopt crypto-agile practices today.
