|participant\_id|[int](../types/int.md) | Yes|ID of the second chat participant|
|g\_a\_or\_b|[bytes](../types/bytes.md) | Yes|`B = g ^ b mod p`, if the currently authorized user is the chat's creator,<br>or `A = g ^ a mod p` otherwise<br>See [Wikipedia](https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange) for more info|
|key\_fingerprint|[long](../types/long.md) | Yes|64-bit fingerprint of received key|