As a student in 1978, Rieks started to develop a Forth system for Utrecht University, taught Forth at Eastman Kodak and the Laboratory for Laser Energetics, and later on – with other students – wrote the operating system, development tools and system application for the first handheld computers (by Matsushita). Up till1990 he wrote real-time and embedded software for projects in several of the Pijnenburg group companies. During this period, Rieks discovered his persistent interest in doing things in different (and supposedly better) ways.
When asked to write software for a crypto-chip, his ideas on improving the chip itself led to the PCC-ISES chip (approx. 1991), the world’s fastest asymmetric crypto chip of that time (doing 207 signatures/second (024-bit RSA)); the crypto core was also used in IBM products.
Around the turn of the century, Rieks moved to KPN Research, where he started to work with relation algebra for conceptual modelling purposes. In conjunction with e.g. the Open University, this led to new ways of specifying business processes, new ways of thinking about identities, and contributions to the further development and operationalization of Ampersand, i.e. the (open source) method and tools for specifying and creating automated support for such processes.
In 2010 Rieks conceived the ideas of what is now called Networked Risk Management (NRM), which is a new way of doing governance, risk management and compliance that are particularly suited for networked organizations that live in highy dynamic and networked contexts.
Rieks currently focuses on business processes, including information (and identity) management and risk management, and ways to support business processes with (generated) IT applications and other novel technologies such as distributed ledger technologies (blockchains)).
Since 2014, Rieks is a contributing expert member of the ISO/IEC JTC1/SC27 WG1 group that manages the 27000 series of IT Security standards.
Since 2000, Rieks has been a board member of primary eductional institutions. He became a member of the supervisory board of Penta Primair in 2011.