Our customers kept wanting to restrict key usage based on core application logic: needing to check state on a different chain before signing, compute over sensitive data, or tie approvals to an external system.
Those kinds of rules don’t fit neatly into a predefined menu—especially when handling keys programmatically—because they’re unique to every product.
That’s what led us to develop Cubist Confidential Cloud Functions (C2F): instead of prescribing a narrow set of rules to govern signing logic, it gives developers the freedom to write their own.
🔍 On-chain verification — check blockchain state before signing (e.g., confirm a burn or liquidity event).
🛡 Cross-chain enforcement — “watch here, act there” logic (e.g., Bitcoin event authorizing action on Ethereum).
🔗 Integrations with external systems — tie approvals to KYC/AML services, fraud monitoring, oracles, LLMs, etc.
🧪 Transaction simulation — run simulations and gate signatures based on the result.
🚦 Smart contract upgrades — require that upgrades are signed by CI pipeline builds and/or approved by auditors.
🔒 Privacy-preserving policies — enforce sensitive approval logic off-chain without exposing it publicly.
🔑 Secret-handling policies — run logic over sensitive data (e.g., trading strategy, cross-chain order book, API keys, etc.) that is dangerous to include in an onchain smart contract.
🧩 Composable attestations — accept or reject transactions based on attestation evidence from trusted enclaves or validators.
The takeaway: for most Web3 use cases, infrastructure security needs to be programmable. Confidential Cloud Functions make key management as expressive as application code.
ALT Cubist C2F: Confidential Cloud Functions for Private Smart Contracts