Messaging and Cryptography Engineer
On contract, build Atumpan's end-to-end encrypted messaging, from protocol design through independent review to handover.
- Team
- Engineering
- Place
- Remote (Ghana)
- Work
- Remote
- Type
- Contract
How you'll work. Fully remote from within Ghana, in our Accra office only on special occasions. A contract for a defined project, with clear milestones.
- You'll be employed by Nkonso Technologies Ltd.
- This role is safety-sensitive: an offer depends on a police clearance certificate.
About the role
Atumpan will keep adults' personal chats end-to-end encrypted, so messages and calls can be read or heard only on the phones in the conversation, while a reported message can still reach our safety team. You'll build that core for groups and for several devices per person, and the bindings our apps use. It's a contract with a clear end: you'll take the work through independent review and hand it over to our security and mobile engineers.
What you'll do
- Design and build the encrypted messaging core on modern, standardised end-to-end encryption protocols for groups
- Support several devices per person, adding and removing them safely
- Build the bindings our iOS, Android and web apps use
- Make reporting work alongside end-to-end encryption, so a reported message can be checked
- Make a change of someone's security code clear and understandable to the people in a chat
- Write the threat model and documentation for independent review, and fix what it finds
- Hand over to our Security Engineer and mobile engineers with documentation and tests
What you'll bring
- Applied cryptography and modern end-to-end encryption protocols, built and shipped in production
- Systems programming in a memory-safe language, including libraries used from mobile platforms
- A deep understanding of group messaging protocols and their security properties
- Experience of threat modelling and working with external reviewers
- Clear technical writing that reviewers can check
- The discipline to work independently on a remote contract, against agreed milestones
- If you're a Ghanaian graduate: National Service completed, or exempt
Nice to have
- Contributions to open-source cryptographic libraries
- Encrypted voice and video calling
- Multi-device sync for encrypted messaging
- Formal methods or protocol verification
How you'll work
- Remote. You'll work fully remotely from within Ghana, joining us at the Accra office only on special occasions.
- Hours. Standard office hours.
- This is a contract for a defined project, with clear milestones and a handover at the end.
- Reporting. You'll report to the Head of Engineering, working day to day with our Security Engineer and mobile engineers.
- Police clearance. This role is safety-sensitive, so an offer depends on a police clearance certificate. We ask for it only at the offer stage, and only with your consent.
How to apply
Apply on this page with your details and a link to your CV. A short note on why the role interests you is welcome.
What happens next: we read every application. If there's a fit, we'll invite you to talk with us, then ask you to do a short task based on the work, and we'll give you an answer either way.
We may use AI to summarise applications and check for missing details. A person reads and decides every application.
We welcome applications from everyone. In line with the Labour Act, 2003 (Act 651), we don't discriminate on grounds of gender, race, colour, ethnic origin, religion, creed, social or economic status, disability or politics. Applicants with disabilities are warmly encouraged to apply: if you need an adjustment to apply or to take part in any stage, tell us what you need and we'll arrange it.
How we handle your details is set out in our applicant privacy notice.
Apply
Takes about five minutes. Every answer is needed unless it says optional.