Information displayed on display screens can easily be observed by an unauthorized person looking over the user’s shoulder or by a zoomed-in visual capture device within visible range of the screen, without the user being aware of such an observer. This form of attack where an unauthorized party obtains access to a user’s information is referred to as shoulder surfing and can lead to disclosure of the information displayed on the screen which is undesirable. This disclosure describes techniques to protect information displayed on a computer screen from such snooping by rendering it as a time-variant, randomly multicolored region. A casual observer perceives with the naked eye the time-variant, randomly multicolored region in place of the sensitive information. A portable device with an authorized decryption app can decode and display the encrypted, multicolored region. In this manner, information on a large screen that is potentially readable by unauthorized persons is rendered illegible to all except the authorized user, who can view it on a small, private screen of the portable device.
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Torres, Michael R., "Privacy in Personal Computing Using Frequency-Hopped Spread Spectrum", Technical Disclosure Commons, (March 20, 2023)