Systems Architecture at Signal Messenger
All Signal cryptographic ratchets (PQXDH, SPQR post-quantum ratchets, Sealed Sender, and anonymous group credentials via ZKGroup) are implemented in side-channel-resistant Rust.
Maintain and evolve `libsignal` and Signal's high-concurrency Rust backend servers protecting post-quantum end-to-end encrypted messaging for 100M+ users. Base pay for this remote role sits at $195,000 to $260,000 USD plus equity.
What You Will Own in Production
- Write constant-time cryptographic primitives, maintain Swift/JNI/TypeScript bridges over `libsignal-ffi`, and scale Rust chat/calling backends.
- Profile CPU cache misses, syscall bottlenecks, and tail latency spikes across rustls, Tokio, Tonic services using hardware perf counters and flamegraphs.
- Review architectural RFCs and maintain strict memory-safety invariants in async and unsafe Rust blocks.
Background We Look For
- Production track record shipping low-level systems in Rust, C, or C++ with deep fluency in rustls, Tokio, Tonic, Prost, no_std.
- Hands-on experience debugging Linux kernel networking, NVMe storage, or GPU compute pipelines under heavy load.
- Compensation: $195,000 to $260,000 USD per year, equity grant, and full remote workstation budget (US Remote).
