Barry O'Callaghan

Cybersecurity Senior Manager · Authorized Instructor @ ISC2

I’m a cybersecurity leader based in Japan — a Senior Manager in Cyber & Information Security at a Big 4 global consulting firm and an authorized ISC2 instructor teaching CISSP, CCSP, and AI strategy.

My background spans offensive security, red teaming, penetration testing, and operational technology (OT) security, anchored by deep expertise in security architecture, incident response advisory, and cyber project management. With a current focus on how AI is reshaping both attack and defense, I bridge the gap between tactical execution and strategic resilience.

I also build open-source security tooling and write about what I learn. This site is where I share tools, writeups, and analysis.

What I focus on
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Offensive AI security — how threat actors and red teams weaponise AI
Red teaming & penetration testing — application and infrastructure testing
Security architecture & incident response — designing resilient systems and guiding organizations through critical security events
Operational Technology (OT) security — securing industrial control systems (ICS/SCADA) and critical infrastructure
Security leadership & project management — strategy, governance, and driving complex international delivery programs
Education — developing the next generation of cybersecurity leaders

Recent

Finding Where Encryption Lives

21 October 2026·2147 words·11 mins

Cryptography Quantum-Computing Cryptography Post-Quantum-Cryptography Inventory Strategy

The first thing you learn in any migration project is that you can’t secure what you can’t see. Quantum readiness is no different. Before anyone upgrades an algorithm or swaps a certificate, the organisation has to answer a much simpler question: where is the cryptography actually sitting?

tls-audit: Audit Any Host's TLS in One Command

21 October 2026·722 words·4 mins

Tools Python Tls Cryptography Tooling Post-Quantum Defense

Security headers are the front door. TLS is the lock. I built sec-headers to check the headers; now here’s tls-audit to check the lock. It’s a Python CLI that connects to a host and reports what it actually negotiates — not what the config file claims. The certificate, which protocol versions are enabled, whether known-weak ciphers are accepted, and whether anything post-quantum is in play.

sec-headers: Audit Your Security Headers in One Command

20 October 2026·592 words·3 mins

Tools Python Web-Security Tooling Headers Defense

Security headers are the cheapest defense you can deploy. They cost nothing, take minutes to configure, and block entire classes of attacks — XSS, clickjacking, MIME sniffing, SSL stripping. Yet most sites get them wrong, or don’t set them at all.

The Day Encryption Stops Working

20 October 2026·1015 words·5 mins

Cryptography Quantum-Computing Cryptography Post-Quantum-Cryptography Security-Strategy

Most threats in cybersecurity give you a sign. A phishing link lands in an inbox. A port scanner rattles the perimeter. A CVE drops with a severity score attached. Something happens, and you get a window to react.

vt-scanner: Check Any File Against VirusTotal in One Command

20 October 2026·461 words·3 mins

Tools Python Virus-Total Malware Tooling

If you handle suspicious files — malware samples, email attachments, downloads from sketchy URLs — you’ve done the dance: hash the file, open VirusTotal, paste the hash, wait, repeat. It’s slow, manual, and burns your attention on process instead of analysis.

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What I focus on#

Recent

What I focus on
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