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{% comment %}
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# MultiFactorAssertion interface
The base class for asserting ownership of a second factor.

This is used to facilitate enrollment of a second factor on an existing user or sign-in of a user who already verified the first factor.

<b>Signature:</b>

```typescript
export interface MultiFactorAssertion 
```

## Properties

|  Property | Type | Description |
|  --- | --- | --- |
|  [factorId](./auth.multifactorassertion.md#multifactorassertionfactorid) | (typeof [FactorIdMap](./auth.md#factorid)<!-- -->)\[keyof typeof [FactorIdMap](./auth.md#factorid)<!-- -->\] | The identifier of the second factor. |

## MultiFactorAssertion.factorId

The identifier of the second factor.

<b>Signature:</b>

```typescript
readonly factorId: (typeof FactorIdMap)[keyof typeof FactorIdMap];
```