Keyboard to App. encryption

In case you may want to increase the security on keyboard: I saw this feature as par of an Internet Security Antivirus and I though was a cool idea; works this way: the stream of characters from the keyboard to any application is captured by the Antivirus (no other application has control over it) and encrypts it, decrypting it only to the application you are typing on, that way any keylogger or other capture utility will get only garbage.

Regards.

What is the overhead on something like this? Sounds like it may be slow/processor intensive.

COMODO already have encryption certificates so a few characters now and then I don’t think would be CPU-heavy.