Senior Golang Engineer (Cryptosigning)

We're looking for a senior Go engineer to take the lead on a transaction-signing service for a Western company building secure infrastructure for digital assets.

The service is the "server-side participant" in a multi-party signing flow: it co-signs transactions together with users' mobile devices using MPC / threshold cryptography, so no single party ever holds a full private key. The core is already built and running your job is to own it, harden it and take it to a solid production level, and later help ship new features such as transaction approval policies and post-quantum signatures.

This is a hands-on ownership role, not a ticket-taking one. You'll get real autonomy and work alongside backend and mobile engineers, QA and a dedicated cryptographer.

What you'll be working on
Owning the Go signing service end to end: coordination between signing parties, encrypted key-share storage, safe recovery after crashes, timeouts and dropped sessions
Hunting down concurrency issues and race conditions, reviewing open PRs and bringing the codebase to a stable, well-tested state Improving logging, metrics and tracing so failures are easy to understand in production
Keeping integrations with MPC / threshold-signature libraries in good shape together with the cryptographer
Contributing to the shared SDKs that expose the Go core to iOS, Android and JS/TS clients, and keeping APIs backward-compatible
Building test coverage for signing correctness, failure scenarios and server mobile interoperability
Supporting Docker/Linux deployments, releases, dependency updates and the occasional production or customer investigation

What we expect
Several years of commercial Go in production you're confident with goroutines, channels, context, the race detector, pprof and resource management
A track record of owning a live service: debugging hard failures and shipping fixes backed by tests
Solid grasp of distributed systems async messaging, retries, idempotency, state handling, partial failures
Security mindset in practice: authentication, encryption at rest, handling secrets and sensitive data, logging without leaking it
Working knowledge of applied cryptography: digital signatures, hashing, key management, signature verification
Comfort with CI/CD, automated testing, containers and observability tooling
Ability to pick up an existing codebase quickly, make careful incremental changes and explain your reasoning
English good enough for daily technical discussions with an international team

Big plus
MPC, TSS or distributed key generation (DKG)
Blockchain transaction signing on any chain
Confidential computing / TEEs and remote attestation (AMD SEV-SNP especially)
gomobile or other Go Swift/Kotlin bindings; TypeScript SDKs; React Native / Expo
MQTT, Protobuf, Prometheus, OpenTelemetry
Interest in post-quantum signature schemes

Terms
Full-time, 100% remote, long-term contract (6+ months, likely extension)
Start ASAP
Core hours 10:0017:00 UK time; possible occasional later calls
Your own laptop is fine

When you apply, it helps a lot if you add
A few words about Go services you've owned in production and your personal role there
An example of a tricky production or security incident you investigated and how you verified the fix
Your GitHub or any public code, if available
Your rate expectations, availability for interviews and earliest start date