Is hiding your Wi-Fi SSID without password secure?

Solution 1:

NO. When you hide your SSID, it is broadcast by clients, so its easy enough to discover anyway (just Googling "discovering hidden SSID" will link you to multiple tools and ways this can be done with relative ease). At that point, free access. There has never been much point in hidden SSIDs.

WIFI passwords are not sent in plain text; they require a significant amount of work (if correctly set up - an unrealistic amount of CPU) to crack.

Solution 2:

Hiding SSIDs is also bad for privacy.

In addition to providing exactly zero security (as the other answers have explained), hiding the SSID is also a very bad idea if you care about privacy.

In a "normal" (not hidden) network, the access point will periodically transmit "beacons" with various information including the SSID. A client thus only needs to passively listen to see what networks are available. If it sees a beacon from one of the configured networks, it can then decide to connect to it.

However, with a hidden SSID, there's no way for a client to know it's in range of a configured network without actively trying to connect. Thus once you set your device to connect to a "hidden" network automatically, it will keep broadcasting "probe requests" with its SSID wherever you go. Sometimes the SSID itself might be somewhat embarrassing or contain personal information, and sharing the list of networks you visited in the past with everyone you meet is often also not desirable.