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# sendSecurityMessage(_:)

Sends a security message to the system.

```
func sendSecurityMessage(_ message: SecurityMessage) throws(AccessorySecuritySession.Error)
```

## Parameters

`message`

A security message containing key material.

## Discussion

Use this method to initiate key exchange by sending a [`SecurityMessage`](/documentation/AccessoryTransportExtension/SecurityMessage) with [`SecurityMessage.KeyType.publicKey`](/documentation/AccessoryTransportExtension/SecurityMessage/KeyType-swift.enum/publicKey). The system responds by calling your handler’s [`messageReceived(_:completion:)`](/documentation/AccessoryTransportExtension/AccessorySecuritySession/EventHandler/messageReceived(_:completion:)) method with encapsulated key material.

---

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