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# URLAuthenticationChallengeSender

The `URLAuthenticationChallengeSender` protocol represents the interface that the sender of an authentication challenge must implement.

```
protocol URLAuthenticationChallengeSender : NSObjectProtocol, Sendable
```

## Overview

The methods in the protocol are generally sent by a delegate in response to receiving a [`connection(_:didReceive:)`](/documentation/Foundation/NSURLConnectionDelegate/connection(_:didReceive:)): or [`download(_:didReceive:)`](/documentation/Foundation/NSURLDownloadDelegate/download(_:didReceive:)-1pc0v):. The different methods provide different ways of responding to authentication challenges.

> Important:
> This protocol is *only* for use with the legacy ``doc://com.apple.foundation/documentation/Foundation/NSURLConnection`` and ``doc://com.apple.foundation/documentation/Foundation/NSURLDownload`` classes. It should not be used with ``doc://com.apple.foundation/documentation/Foundation/URLSession``-based code, for which you respond to authentication challenges by passing ``doc://com.apple.foundation/documentation/Foundation/URLSession/AuthChallengeDisposition`` constants to the provided completion handler blocks.

## Topics

### Protocol Methods

[`cancel(_:)`](/documentation/Foundation/URLAuthenticationChallengeSender/cancel(_:))

Cancels a given authentication challenge.

[`continueWithoutCredential(for:)`](/documentation/Foundation/URLAuthenticationChallengeSender/continueWithoutCredential(for:))

Attempt to continue downloading a request without providing a credential for a given challenge.

[`use(_:for:)`](/documentation/Foundation/URLAuthenticationChallengeSender/use(_:for:))

Attempt to use a given credential for a given authentication challenge.

[`performDefaultHandling(for:)`](/documentation/Foundation/URLAuthenticationChallengeSender/performDefaultHandling(for:))

Causes the system-provided default behavior to be used.

[`rejectProtectionSpaceAndContinue(with:)`](/documentation/Foundation/URLAuthenticationChallengeSender/rejectProtectionSpaceAndContinue(with:))

Rejects the currently supplied protection space.


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