The idea could be used for whenever you need to use a password and its main function is to utilize different kind of human memory capabilities.
The system in short.
Take some standard character table and make a challenge image of it. The computer then generates a random password of fix size from the characters in the table. Then the system trains the user on the generated password with the help of the challenge image. Similar to the way you train on a numerical table for a passage door. So then when you have to enter the password, the challenge image is there with it to help you remember.
Some standard character table.
Updated with a simpler challenge image
The computer generated password, 'BJ/a$l' gives you a number of '251 205'. With the number you easily remember, you get extra guidance for which characters the password contains.
The main thing is that you are represented with a challenge image of the characters like the numerical table on passage door systems. With a touch screen this makes for a perfect analogy. A challenge image makes it much easier to remember a password in my opinion.
To test this you can print out a large copy of the challenge image on a piece of paper. Generate a random password. Learn the guidance number then move your finger to the position of characters of the password. Later see how long it took to learn a complicated password using the challenge image.
If you draw with a pen from the start of the password all the characters to the end you get signature. This could be used with mouse gestures to quickly generate a password when needed. No need to press any keys just draw the signature on the screen with your mouse.
Some of my training, but it works.
Circles indicate mouse clicks.