# getIdentityIdByFirstPublicKey

**Usage**: `async client.platform.getIdentityIdByFirstPublicKey(publicKeyHash)`  
**Description**: Fetch the identity ID using the public key hash of the identity's first key

Parameters:

| parameters        | type   | required | Description             |
| ----------------- | ------ | -------- | ----------------------- |
| **publicKeyHash** | String | yes      | A valid public key hash |

Returns : Promise\<!Buffer|null>