|key\_hash|[bytes](../types/bytes.md) | Yes|Hash of the current used key for comparison with the hash of the interlocutor's key. String of 36 bytes, which should be used to make a 12x12 square image with a color depth of 4. First 16 bytes should be used to make a central 8 * 8 square, left 20 bytes should be used to construct a border of width 2 around that square. Alternatively first 32 bytes of the hash can be converted to hex and printed as 32 2-digit hex numbers|
|layer|[int](../types/int.md) | Yes|Secret chat layer, determining features supported by other client. Video notes are supported if layer >= 66|