---
title: first
framework: authenticationservices
role: symbol
role_heading: Instance Property
path: authenticationservices/asauthorizationpublickeycredentialprfregistrationoutput-swift.struct/first
---

# first

A symmetric key that’s unique to the passkey and derives from the first input, if specified.

## Declaration

```swift
let first: SymmetricKey?
```

## See Also

### Accessing symmetric keys

- [second](authenticationservices/asauthorizationpublickeycredentialprfregistrationoutput-swift.struct/second.md)