Senior Security Engineer - xStocks

As a Senior Security Engineer at Ink Foundation, you join the xStocks team to secure the infrastructure that issues, custodies, and settles tokenized real-world assets across EVM, Solana, TON, Tron, and more. This is a hybrid engineering and security role: you ship products alongside the engineering team when the security queue is quiet, and you own security work end to end when it lands. You report into engineering and partner closely with Payward's security, CISO, and compliance functions.

What you'll do

• Own security deliverables end to end. Coordinate and review smart-contract audits, respond to security questionnaires and due-diligence requests, support CISO and compliance initiatives, and drive findings into tracked, closed-out fixes.
• Run offensive assessments against your own platforms. Pentest the web apps, APIs, backend services, and on-chain components, and build the tooling to repeat assessments rather than conduct them once.
• Continuously assess security posture. Threat-model new and existing systems, review architecture and key-management flows, and maintain a living view of risks and their mitigations.
• Review code for security. Serve as a default reviewer on changes touching auth, cryptography, custody, signing, and fund movement across chains.
• Harden the platform. Improve secrets handling, IAM and least-privilege, dependency and supply-chain hygiene, and detection and logging for security-relevant events.
• Secure custody and signing workflows. Review and harden transaction signing flows, MPC and HSM integrations, signer permissions, admin roles, approval policies, and break-glass procedures.
• Contribute to product engineering. Pick up regular backlog work in TypeScript to stay close to the codebase you defend.
• Support incidents. Help with detection, triage, response, and post-mortems, and feed lessons back into the security program.

What you bring

• An engineering foundation. You write and review production code comfortably in TypeScript and Node.js, and you understand systems deeply enough to break them.
• Strong application and infrastructure security fundamentals. The OWASP-class vulnerability landscape, authn and authz, injection, SSRF, supply-chain risk, and secure design. You have performed real offensive work in pentesting, vulnerability research, or red-team.
• Applied cryptography and blockchain security. Symmetric and asymmetric primitives, hashing, signatures, and key management, plus the security model of EVM, Solana, and ideally TON or Tron. You can read a smart contract and reason about how it fails.
• Ownership. You can take an ambiguous security item, an audit, a questionnaire, or an incident, and drive it to closure without being managed through it.
• Clear communication. You can explain a risk to engineers, to a CISO, and to an auditor, and tailor the message to each audience.
• An automation instinct. You do not want to catch the same issue manually twice, so you turn findings into tests, alerts, controls, documentation, or platform improvements.
• Risk judgment. You can tell a theoretical issue from a material one, and communicate severity, likelihood, impact, and remediation tradeoffs clearly.

Nice to have

• Experience commissioning or remediating third-party smart-contract audits.
• Familiarity with custody and signing infrastructure such as HSMs, MPC, and ForDefi-style providers, and with on-chain transaction security.
• Cloud security depth in GCP or AWS, IAM, and container and runtime hardening.
• Detection engineering and security observability, including SIEM and log-based detections.
• Relevant certifications such as OSCP, OSWE, or GWAPT.
• Prior work in a regulated fintech or tokenization and DeFi environment.

About Ink Foundation

Payward, the parent company of xStocks, Kraken, NinjaTrader, Breakout, and CF Benchmarks, has spent 15 years building a modern, globally accessible financial infrastructure platform designed to advance an open, global financial system.