> ## Documentation Index
> Fetch the complete documentation index at: https://docs.crossmint.com/llms.txt
> Use this file to discover all available pages before exploring further.

# useSigner

> Kotlin Function

**Function**

```kotlin theme={null}
suspend fun Wallet.useSigner(signer: DelegatedSigner.Passkey, credentialManager: CredentialManager, activityProvider: () -> Activity, rpId: String): Result<Unit, WalletError>
```

Activates a passkey signer on an EVM, Solana or Stellar wallet. On Solana, the passkey must be a delegated signer. Each time the wallet signs, the SDK calls activityProvider and shows the passkey prompt over that Activity.