Quantum Security Engineer

Remote worldwide

Full-time / Part-time / Contract

Help organisations migrate existing codebases towards quantum-resistant security. You will assess cryptographic dependencies, implement post-quantum cryptography and test changes in real systems. International remote applications are welcome, with full-time, part-time or contract arrangements depending on project requirements and availability.

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What you'll do

This is a hands-on engineering role. You will work inside existing codebases, understand how they use cryptography and deliver changes that can be reviewed, tested and maintained.

Assess code and dependencies. Trace cryptographic use across applications, libraries, protocols, certificates and infrastructure. Identify quantum-vulnerable key exchange and signatures, data confidentiality requirements and implementation weaknesses.
Plan migrations. Turn assessment findings into scoped engineering tasks, prioritised by risk, system constraints and operational impact. Coordinate with client teams and suppliers where changes depend on external services or protocol support.
Implement PQC. Integrate suitable NIST-standardised algorithms, including ML-KEM, ML-DSA and SLH-DSA where appropriate, through maintained, reviewed cryptographic libraries. Use supported hybrid approaches when the protocol and deployment require them. Do not design custom cryptographic primitives.
Upgrade integrations. Refactor relevant key exchange, digital signature, authentication and certificate workflows. Update dependencies and protocol configurations, including TLS and PKI where supported, while assessing compatibility and downgrade risks.
Strengthen key management. Review secure key generation, storage, access controls, rotation and revocation. Assess KMS or HSM integration, secrets handling, entropy requirements and secure defaults as part of the migration.
Build for cryptographic agility. Reduce hard-coded algorithm assumptions and make future cryptographic changes manageable without weakening the system's security model.
Test the result. Write unit, integration, regression and interoperability tests. Use appropriate test vectors, fuzzing and performance benchmarks. Assess changes to latency, memory, key and signature sizes, and involve specialist review for side-channel and implementation risks.
Protect the wider software lifecycle. Address related dependency, supply-chain and secrets-management issues. Add appropriate CI checks, code review and release controls. PQC adoption must not introduce new conventional security weaknesses.
Deliver evidence and a safe handover. Document design decisions, remaining limitations, test results and remediation status. Support staged deployment, recovery planning and post-release monitoring, with clear guidance for the teams maintaining the code.

What you'll do

This is a hands-on engineering role. You will work inside existing codebases, understand how they use cryptography and deliver changes that can be reviewed, tested and maintained.

Assess code and dependencies. Trace cryptographic use across applications, libraries, protocols, certificates and infrastructure. Identify quantum-vulnerable key exchange and signatures, data confidentiality requirements and implementation weaknesses.
Plan migrations. Turn assessment findings into scoped engineering tasks, prioritised by risk, system constraints and operational impact. Coordinate with client teams and suppliers where changes depend on external services or protocol support.
Implement PQC. Integrate suitable NIST-standardised algorithms, including ML-KEM, ML-DSA and SLH-DSA where appropriate, through maintained, reviewed cryptographic libraries. Use supported hybrid approaches when the protocol and deployment require them. Do not design custom cryptographic primitives.
Upgrade integrations. Refactor relevant key exchange, digital signature, authentication and certificate workflows. Update dependencies and protocol configurations, including TLS and PKI where supported, while assessing compatibility and downgrade risks.
Strengthen key management. Review secure key generation, storage, access controls, rotation and revocation. Assess KMS or HSM integration, secrets handling, entropy requirements and secure defaults as part of the migration.
Build for cryptographic agility. Reduce hard-coded algorithm assumptions and make future cryptographic changes manageable without weakening the system's security model.
Test the result. Write unit, integration, regression and interoperability tests. Use appropriate test vectors, fuzzing and performance benchmarks. Assess changes to latency, memory, key and signature sizes, and involve specialist review for side-channel and implementation risks.
Protect the wider software lifecycle. Address related dependency, supply-chain and secrets-management issues. Add appropriate CI checks, code review and release controls. PQC adoption must not introduce new conventional security weaknesses.
Deliver evidence and a safe handover. Document design decisions, remaining limitations, test results and remediation status. Support staged deployment, recovery planning and post-release monitoring, with clear guidance for the teams maintaining the code.

What we're looking for

Strong software engineering skills and experience reading, debugging and modifying unfamiliar production codebases. Depth in one or more relevant languages, such as Rust, Go, C/C++, Python or TypeScript, is more important than knowing every language.
A sound understanding of applied cryptography, including public-key cryptography, key establishment, digital signatures, authenticated encryption and key management.
Working knowledge of post-quantum cryptography, the NIST PQC standards and the practical differences between key encapsulation and signature schemes.
Experience integrating established cryptographic libraries securely, recognising unsafe API use and evaluating dependencies rather than implementing cryptography from scratch.
Experience with threat modelling, secure code review, automated testing, Git and CI/CD. You should be able to explain what a change protects against and how you checked it.
Clear written communication, careful handling of confidential client material and the ability to work with a remote team.

Useful additional experience

Previous PQC migration or cryptographic library integration work.
TLS, PKI, certificate lifecycles, cloud key management or HSMs.
Security research, fuzzing, performance analysis or side-channel assessment.
On-chain systems, digital asset custody or signing infrastructure.

What we're looking for

Strong software engineering skills and experience reading, debugging and modifying unfamiliar production codebases. Depth in one or more relevant languages, such as Rust, Go, C/C++, Python or TypeScript, is more important than knowing every language.
A sound understanding of applied cryptography, including public-key cryptography, key establishment, digital signatures, authenticated encryption and key management.
Working knowledge of post-quantum cryptography, the NIST PQC standards and the practical differences between key encapsulation and signature schemes.
Experience integrating established cryptographic libraries securely, recognising unsafe API use and evaluating dependencies rather than implementing cryptography from scratch.
Experience with threat modelling, secure code review, automated testing, Git and CI/CD. You should be able to explain what a change protects against and how you checked it.
Clear written communication, careful handling of confidential client material and the ability to work with a remote team.

Useful additional experience

Previous PQC migration or cryptographic library integration work.
TLS, PKI, certificate lifecycles, cloud key management or HSMs.
Security research, fuzzing, performance analysis or side-channel assessment.
On-chain systems, digital asset custody or signing infrastructure.

What we offer

Remote worldwide. We welcome international applicants.
Flexible engagement. Full-time, part-time or contract arrangements, depending on project requirements and your availability.
Practical security work. Help turn quantum-risk findings into tested improvements to real codebases, alongside QuantSec's engineering and research work.

Scope, hours and engagement terms will be agreed during the hiring process.

How to apply

Email [email protected] with the subject "Quantum Security Engineer Application". Include your CV or professional profile, relevant projects or public code, your timezone, availability and preferred engagement type. Please do not send confidential code or materials from previous employers or clients.

What we offer

Remote worldwide. We welcome international applicants.
Flexible engagement. Full-time, part-time or contract arrangements, depending on project requirements and your availability.
Practical security work. Help turn quantum-risk findings into tested improvements to real codebases, alongside QuantSec's engineering and research work.

Scope, hours and engagement terms will be agreed during the hiring process.

How to apply

What we offer

Remote worldwide. We welcome international applicants.
Flexible engagement. Full-time, part-time or contract arrangements, depending on project requirements and your availability.
Practical security work. Help turn quantum-risk findings into tested improvements to real codebases, alongside QuantSec's engineering and research work.

Scope, hours and engagement terms will be agreed during the hiring process.

How to apply

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Apply

Apply for Quantum Security Engineer.

Email your CV or professional profile, relevant projects or public code, timezone, availability and preferred engagement type to [email protected]. Use the subject: Quantum Security Engineer Application. Please do not send confidential code or client materials.

Email [email protected]