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# ASAuthorizationPublicKeyCredentialLargeBlobAssertionInput

A type that represents input for the binary large object extension in passkey assertion requests.

```
struct ASAuthorizationPublicKeyCredentialLargeBlobAssertionInput
```

## Overview

Use this type during assertion (sign-in) with an existing passkey.
An app can specify exactly one operation to perform during the sign-in: either read the existing saved blob or write a new blob (overwriting the existing one, if applicable).
This restriction mirrors the operations available in the WebAuthn specification.

## Topics

### Using assertion inputs

[`read`](/documentation/AuthenticationServices/ASAuthorizationPublicKeyCredentialLargeBlobAssertionInput-swift.struct/read)

An operation to read the existing blob value.

[`write(_:)`](/documentation/AuthenticationServices/ASAuthorizationPublicKeyCredentialLargeBlobAssertionInput-swift.struct/write(_:))

An operation to write the blob value, overwriting any existing value.

### Inspecting the operation

[`operation`](/documentation/AuthenticationServices/ASAuthorizationPublicKeyCredentialLargeBlobAssertionInput-swift.struct/operation-swift.property)

The reading or writing operation the input performs.

[`ASAuthorizationPublicKeyCredentialLargeBlobAssertionInput.Operation`](/documentation/AuthenticationServices/ASAuthorizationPublicKeyCredentialLargeBlobAssertionInput-swift.struct/Operation-swift.enum)

A type to represent the possible operations of a large binary object assertion input.


---

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