Introducing MPC Presignatures: Faster Signing for High-Frequency Apps

In a payments app, a trading interface, or an agent acting onchain, signing is not an occasional event. It is the product. Every send, every trade, every card authorization ends in a signature, and when a wallet signs that often, responsiveness is the difference between an app that feels native and one that feels like it's waiting on a network.

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MPC Presignatures keep that moment fast. Portal prepares most of the signature in advance, so when your app actually needs one, it comes together right away.

How it works

Portal wallets sign with multi-party computation: the signature is produced across distributed key shares, and no single party ever holds the full private key. Here's the useful detail: a large part of that computation doesn't depend on the transaction being signed. It can be done early.

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That's exactly what presignatures do. Portal generates presignature material in the background and keeps a buffer of it ready. When your app calls the same signing methods it already uses, the prepared material is waiting, and only the final, transaction-specific step happens in the moment. Your user keeps moving.

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You don't rewrite anything. Transactions, sends, and approvals all go through the methods you're already calling.

Built for the moments that can't wait

The clearest example is card payments. When a user taps a crypto-backed card, the card networks require an approve or decline within a strict authorization window, and for a self-custodial card that answer can depend on producing a signature. Presignatures keep the online signing step short enough to answer inside that window, so a card program can approve in time without giving up threshold MPC security.

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The same logic applies anywhere signatures stack up: payment flows settling in real time, trading screens where every tap is a signature, and agents executing multi-step actions on a user's behalf. Teams running the Enclave MPC API see the clearest gains, since a ready buffer keeps throughput high for server-side and high-volume workloads.

Security stays exactly where it should

Presignatures change when the work happens, not how the wallet is protected. Key shares are never combined into a single private key, and the precomputed material contains no secret key data on its own. It is stored securely on the device alongside the rest of Portal's MPC state. A wallet using presignatures has the same security model as one that doesn't. It just signs faster.

Get started

Presignatures are available today in the Portal iOS, Android, React Native, and Flutter SDKs. Turn on one feature flag in your Portal options and Portal handles the rest: background generation, secure storage, and keeping presignatures ready for every signature your app requests.

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Building a card program, a payments app, or a trading product? Give your users instant signing backed by the full security of MPC and Threshold Signing. Enable presignatures today with the feature flag guide in our docs, or talk to our team about what you're building.

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