Presignatures

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Overview

Presignatures allow you to split the MPC signing protocol into two phases:

1. Pre-computation phase — Generate a presignature ahead of time using the presign endpoint.
2. Signing phase — Pass the presignature to a sign, raw sign, or send asset endpoint to complete the signature faster.

By front-loading part of the cryptographic computation, the signing step completes faster. This is useful when you need lower-latency signing at transaction time or want to prepare signatures in advance for time-sensitive operations.

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How It Works

The Enclave MPC API supports two presignature storage modes: In both modes, the signing endpoint uses the pre-computed data to complete the MPC protocol faster.

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Key Details

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Use Cases

• Low-latency signing — Pre-compute during idle time so that user-facing sign requests complete faster.
• Batch preparation — Generate multiple presignatures in advance for a batch of upcoming transactions.
• Time-sensitive transactions — Prepare presignatures before a deadline so signing is fast when needed.

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Compatible Endpoints

Presignatures can be used with the following Enclave MPC API endpoints:

• Sign (POST /v1/sign) — RPC-based signing (e.g., eth_sendTransaction)
• Raw Sign (POST /v1/raw/sign/SECP256K1) — Sign a hex digest string
• Send Assets (POST /v1/assets/send) — High-level token transfer

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Best Practices

• For client-stored presignatures, store the id and expiresAt alongside the data value. While the id is not required for signing, it is useful for bookkeeping and may be needed when communicating with Portal support.
• For Portal-managed presignatures, store the id and expiresAt so you can pass the id as presignatureId and clean up expired presignatures.
• Discard expired presignatures — set up a regular process to check expiresAt timestamps and clean up expired entries so you stay within the 100 active presignature limit.

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SDK behavior

The SDK manages presignatures automatically when you enable the usePresignatures feature flag. With the flag enabled, the SDK generates presignatures in the background and uses them during signing (e.g. portal.request() or send-asset flows) to improve latency

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Next Steps

Ready to use presignatures? Choose your platform:

• Presignatures with Enclave MPC API — For server-side or custom integrations.
• React Native — Enable the usePresignatures feature flag when initializing Portal
• Web — Enable the usePresignatures feature flag when initializing Portal