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Tech Blog

In-depth articles on payments, security, AI and architecture — written by those who operate these systems in production.

Security12 min

Frida on Android: Dynamic Instrumentation, Bypass and APK Repackaging

How to use Frida for dynamic instrumentation on Android apps — method hooking, SSL Pinning bypass, root check bypass and APK repackaging with APKTool.

May 26, 2026Read article
Security10 min

Static APK Analysis with JADX and Ghidra

How to use JADX for Java/Kotlin decompilation and Ghidra for native library (.so) analysis in Android apps — complete static analysis workflow for pentesting.

May 26, 2026Read article
Security8 min

How to Implement SSL Pinning on Android

SSL Pinning is a technique that prevents Man-in-the-Middle attacks on Android applications by pinning the expected certificate directly in the app. Learn how to implement it correctly.

November 10, 2025Read article
Payments10 min

How ISO8583 Works: The Protocol Behind Payments

ISO8583 is the messaging standard used by virtually every payment terminal in the world. Understand its structure, message types, and how to implement a basic integration.

October 20, 2025Read article
Security9 min

What Is PCI DSS and What Changed in Version 4.0

PCI DSS is the mandatory security standard for any organization that processes, stores, or transmits cardholder data. Understand the 12 requirements, compliance levels, and what changed in version 4.0.

September 15, 2025Read article
Security8 min

How an HSM Works and Why It Is Indispensable in Payment Systems

A Hardware Security Module (HSM) is the guardian of cryptographic keys in financial systems. Understand how it works, what operations it performs, and why no serious payment system operates without one.

August 28, 2025Read article
Tech Blog — APCosta