Security-Focused Backend Engineer Brussels, Belgium Hybrid 2 days on-site, 3 days work from home Up to €420/day 12 months contract - possibility of extensionAre you a back-end engineer with a passion for cybersecurity and secure system integration? This is your chance to make an impact on high-level international projects!We’re looking for a Secure Data and Document Expert to join one of our public sector clients in Brussels. You'll contribute to essential digital transformation initiatives that prioritise data confidentiality, integrity, and secure interoperability.Your Role:In this role, you’ll act as the go-to expert for secure data exchange, ensuring that critical messaging systems meet the highest security standards. Key responsibilities include:Designing and implementing secure integration layers between backend systems and messaging softwareAdvising on all aspects of secure data transmission: confidentiality, integrity, authentication, and availabilityConducting security assessments and supporting vulnerability testingMaintaining and optimising transport/messaging protocol specificationsCollaborating with cross-functional teams to guide integration strategy and technical documentationYour Qualifications:A Master's degree with 5+ years (or Bachelor’s with 9+ years) of experience in secure document exchange and protectionStrong knowledge of digital signatures, PKI, ASiC, X.509, and eIDAS complianceDeep expertise with secure messaging and transfer protocols such as ebMS3, AS4, XML, JSON, and BDXLBackend development proficiency in Java with strong knowledge of OOP, SQL databases, and transactional consistency (ACID/XA)3+ years of mobile development experience on both Android (Java/Kotlin) and iOS (Swift)Familiarity with CI/CD pipelines and observability tools (Jenkins, Git, SonarQube, Selenium, JMeter, Dynatrace, Splunk)Experience with containers and infrastructure: Docker, Kubernetes, Linux, TPM, HSMFluency in English and French (C1 level), with strong communication and documentation skillsBonus Points For:Experience with EU institutionsSANS Web Application Tester certificationFamiliarity with TPM/HSM-based cryptographic hardwareAgile project delivery using SCRUM or OpenPM2Certifications in cybersecurity, project management, or software development5V Tech are acting as an Agency for the purposes of this contract. We offer a reward scheme if you can recommend someone for this contract, up to €250 for you and an additional €250 to a charity of your choice. 5V Tech are recognised talent solutions experts within IoT and Deep Tech working across Europe, the UK and North America.