Is it possible to get the gesture.key without a rooted phone?
Is it possible to get key if unable to enable ADB on phone?
I try to answer these questions but have to say this may not be the latest or most correct info, but just something I have learned when doing stuff with my own devices.
Answer to both questions is yes in theory,but it still needs quit optimal conditions. If phone has custom recovery or if you can flash one to it(which does not require rooted device), then you can boot to recovery, mount /data partition and copy gesture.key to external sdcard or usb device via otg. Atleast TWRP has file manager and terminal access in it, so it can be done with one of those tools. But phone's bootloader might need to be unlocked(in case of flashing something to it), then it's kind of game over because unlocking bootloader wipes the device completly.
----End of the actual answer---
As additional info. if pattern doesn't need to be cracked and you could freely just tamper with the device then in most android versions/devices you could also just disable pattern lock if you can get access to /data partition. I know this is very common knowledge to most but if phone is running kitkat or earlier android you could just delete gesture.key and pattern lock gets disabled.
With my Nexus5 running Android 5.1 I was able to disable pattern lock with tampering "data/system/locksettings.db"-database.
sqlite3 /data/system/locksettings.db
delete from locksettings where name='lockscreen.password_type';
.exit;
Then reboot and pattern lock was disabled. Not sure how widely this works in different devices/lollipop versions and you would need to push copy of sqlite3 to phone if it doesn't have it already.
But really nice tool anyways op +1.