--- title: cdnPublicKey description: Public key to use **only** during handshakes to [CDN](https://core.telegram.org/cdn) DCs. image: https://docs.madelineproto.xyz/favicons/android-chrome-256x256.png --- # Constructor: cdnPublicKey [Back to constructors index](index.md) Public key to use **only** during handshakes to [CDN](https://core.telegram.org/cdn) DCs. ### Attributes: | Name | Type | Required | Description | |----------|---------------|----------|-------------| |dc\_id|[int](../types/int.md) | Yes|[CDN DC](https://core.telegram.org/cdn) ID| |public\_key|[string](../types/string.md) | Yes|RSA public key| ### Type: [CdnPublicKey](../types/CdnPublicKey.md) ### Example: ```php $cdnPublicKey = ['_' => 'cdnPublicKey', 'dc_id' => int, 'public_key' => 'string']; ``` Or, if you're into Lua: ```lua cdnPublicKey={_='cdnPublicKey', dc_id=int, public_key='string'} ```