There was always a concern over wireless keyboards, though good designs have mitigated snooping on their wireless signals. But now it looks like wired keyboards (with poor shielding?) offer no guarantee of privacy.

Compromising Electromagnetic Emanations of Wired Keyboards - Security and Cryptography Laboratory - LASEC/EPFL

To determine if wired keyboards generate compromising emanations, we measured the electromagnetic radiations emitted when keys are pressed. To analyze compromising radiations, we generally use a receiver tuned on a specific frequency. However, this method may not be optimal: the signal does not contain the maximal entropy since a significant amount of information is lost.

Our approach was to acquire the signal directly from the antenna and to work on the whole captured electromagnetic spectrum.
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