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Built cryptographic infrastructure for verifiable integrity and tamper-proof audit trails in regulated environments. The systems were offline-first and independently verifiable from disk, without requiring changes to existing infrastructure. The cryptographic core combined hash chaining, Merkle trees, content-addressed storage, threshold cryptography (3-of-5), ECDSA signatures and multi-layer AES-GCM. On top of that I implemented forensic evidence capture with ephemeral session keys, deterministic evidence vaults, and append-only cryptographic audit trails with certified exports. Compliance was a first-class concern: the work was mapped to FDA 21 CFR Part 11, ANVISA RDC 657/2022, EU GMP Annex 11 and ALCOA+, with supporting validation documentation including FMEA risk assessment, IQ/OQ/PQ protocols and data integrity controls. Backend services used RFC 7807/9457, RFC 3339, RFC 9110 and RFC 3161, with architecture spanning microservices, monoliths, actor-based systems and pub/sub. BFF and gateways ran in Node.js/Deno (TypeScript), with Redis for caching and coordination. Infrastructure was on Docker, Docker Compose/Swarm and containerd (OCI).

Crypto backend and infrastructure engagements through Quantum Theorem, working directly against full nodes on Bitcoin, Liquid, Ethereum, Solana and Monero across regtest, testnet and mainnet. The work spanned node deployments, RPC services and payment pipelines, with applied cryptography holding the layer together. On the swap side, I built OTC operations and swap mechanisms including HTLC-based swaps and micro-swaps across Bitcoin, Ethereum and Liquid, plus HD wallets with mnemonic support compiled to WASM for browser and mobile via WASI. Fiat on/off-ramp integrations carried through the full payment pipeline: address generation, confirmation tracking, reorg handling, idempotent webhooks and reconciliation, all built on a decade of payments experience. For smart contracts, I shipped EVM applications in Solidity covering tokens, access control, vesting and swap contracts, integrated against contracts others had shipped rather than auditing them. On infrastructure I wrote custom Go orchestrators on top of containerd and OCI, deploying reproducible node setups where the same image ran in CI and production. Backend services followed RFC 7807/9457 for problem details, RFC 3339 for timestamps, RFC 9110 for HTTP semantics and RFC 3161 for trusted timestamping. Architecture mixed microservices, monoliths, actor-based systems and pub/sub, with BFF and gateways in Node.js/Deno (TypeScript). Go and Rust were the primary languages, with Solidity, Bitcoin Script, Erlang and OCaml where they fit.