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# sec_protocol_challenge_t

```
typealias sec_protocol_challenge_t = (sec_protocol_metadata_t, @escaping sec_protocol_challenge_complete_t) -> Void
```

## Parameters

`metadata`

A `sec_protocol_metadata_t` instance.

`complete`

A `sec_protocol_challenge_complete_t` to be invoked when the challenge is complete.

## Discussion

\abstract Block to be invoked when the protocol instance is issued a challenge (e.g., a TLS certificate request).

---

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