How SIP (RFC 3261) sets up, modifies, and tears down multimedia sessions using a text request/response model, its elements, layered design, transactions, dialogs, and security.
2026, Jul 20 — 21 minute readA technical walkthrough of the PCI PTS POI Modular Security Requirements v7.0, the standard that governs payment terminals, from tamper resistance and PIN protection to account-data encryption, wireless security, and third-party applications.
2026, Jul 20 — 26 minute readA technical walkthrough of the PCI PTS HSM Modular Security Requirements v4.0, the standard that defines how payment Hardware Security Modules are evaluated, from tamper resistance and key separation to cloud multi-tenant isolation.
2026, Jul 20 — 26 minute readA guided tour of RFC 6071, the roadmap that maps the sprawling IPsec and IKE RFC landscape - the seven document groups, IPsec-v2 vs v3, IKEv1 vs IKEv2, extensions, and crypto requirement levels.
2026, Jul 20 — 13 minute readHow HOTP (RFC 4226) turns a shared secret and a counter into a 6-digit one-time password using HMAC-SHA-1 and dynamic truncation, with its security analysis, validation rules, and link to TOTP.
2026, Jul 20 — 16 minute readA formal walkthrough of the Brewer and Nash Chinese Wall security policy, its conflict-of-interest access rules, its *-property against indirect flows, and why it cannot be reduced to Bell-LaPadula.
2026, Jul 20 — 15 minute readA technical walkthrough of the 1973 Black-Scholes paper - the no-arbitrage hedging argument, the option pricing differential equation, its closed-form solution, and the reading of corporate liabilities as options.
2026, Jul 18 — 21 minute read