# Authenticator.getSignCount

Extracts the signature counter from the authenticator data. The counter is a 4-byte big-endian unsigned integer at bytes 33–36.

Useful for detecting cloned authenticators: if the counter is non-zero and does not monotonically increase between assertions, it may indicate a cloned key.

## Imports

:::code-group
```ts [Named]
import { Authenticator } from 'ox/webauthn'
```

```ts [Entrypoint]
import * as Authenticator from 'ox/webauthn/Authenticator'
```
:::

## Examples

```ts twoslash
import { Authenticator } from 'ox/webauthn'

const signCount = Authenticator.getSignCount(
  '0x49960de5880e8c687434170f6476605b8fe4aeb9a28632c7995cf3ba831d97630500000001'
)
// @log: 1
```

## Definition

```ts
function getSignCount(
  authenticatorData: Hex.Hex | Uint8Array,
): number
```

**Source:** [src/webauthn/Authenticator.ts](https://github.com/wevm/ox/blob/main/src/webauthn/Authenticator.ts#L171)

## Parameters

### authenticatorData

* **Type:** `Hex.Hex | Uint8Array`

The authenticator data hex string.

## Return Type

The signature counter.

`number`