Internship: Java Team: Remove type information from method prototype @ Guardsquare in Leuven (BE)


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Duration: 1+ months



In our Leuven-based Java team we work on manipulating Java bytecode. All our software is based on our open source bytecode manipulation library ProGuardCORE ( ).
On top of ProguardCORE we mainly develop 2 different products: ProGuard and DexGuard. ProGuard is a shrinker and optimizer for all Java and Android applications, it makes them smaller and faster. DexGuard is a code hardening tool, which makes Android apps harder to understand for a reverse engineer.



One of the protections we offer consists of obfuscating the code embedded on mobile applications, such as obfuscating the identifiers, changing the code structure, … These protections can be improved by removing type information from method prototypes. For instance, it would turn 

String doOperation(SomeParameter a, OtherType b)


Object doOperation(Object a, Object b)

This removes a lot of semantic information from the target application, but relies on injecting type casting information wherever parameters are used. 

In this internship you will get acquainted with automated java bytecode manipulation. You will create a new pass which removes typing information applications, and make sure that such modifications can be applied on real-world applications.



  • Java/Kotlin experience
  • Interest in Java bytecode/JVM-level


About Guardsquare:

Guardsquare offers the most complete approach to mobile application security on the market. Built on the open source ProGuard technology, Guardsquare’s software integrates seamlessly across the development cycle. From app security testing to code hardening to real-time visibility into the threat landscape, Guardsquare solutions provide enhanced mobile application security from early in the development process through publication.

More than 900 customers worldwide across all major industries rely on Guardsquare to help them identify security risks and protect their mobile applications against reverse engineering and tampering.

Guardsquare is based in Leuven (Belgium) with offices in Boston (USA) and Munich (Germany).



At Guardsquare, we take pride in being a diverse and multicultural company with team members representing numerous nationalities. We value different perspectives and opinions throughout the business which has contributed to our being the market leader in mobile application security. 

You will be part of a dynamic team that strives for excellence and focuses on continuous education and enhancement in skills. We encourage & empower our trusted colleagues to share their opinions, actively collaborate, and continue to learn and grow.