All icons are public domain.

Pulled mostly from this source https://github.com/apancik/public-domain-icons.

lock.svg by Lorc under CC BY 3.0
https://game-icons.net/1x1/lorc/padlock.html

unlock.svg by Delapouite under CC BY 3.0
https://game-icons.net/1x1/delapouite/padlock-open.html

bubbles.svg by Lorc under CC BY 3.0
https://game-icons.net/1x1/lorc/bubbles.html