Hardware based keyloggers are generally more complex
that software keyloggers and is much hard to detect. In today’s world
keyloggers are the most powerful applications used for gathering
information commonly by encrypted traffic.

There are some features common in all hardware keyloggers, as they all must have-

A non-volatile memory device
– Non volatile memory such as flash memory uses to store all the
recorded information and retains them even when power is lost.

A microcontroller
– It is the heart of keyloggers which interrupts the data strea,
between the computer and keyboard and posses it and then sends to the
memory for storing.

How hardware keyloggers works?

Hardware keyloggers are implemented via BIOS level firmware or through a
device plug-in between the computer and computer keyboard. They have
inbuilt memory which is use to store all the log keyboard activity for
later encryption use. Almost in all cases the recorded data is retrieved
by typing some kinds of special words or special password into a text
editor of the computer which after detecting by the keyloggers send to
the computer to produce a menu. Apart from producing menu some of the
keyloggers provide high speed download which stimulate the retrieval
process of stored data.

Hardware keyloggers provides huge storage capacity typical the memory
capacity of range of few kilobytes to hundreds gigabytes in which each
keystroke record consume just a byte of memory space.

Types:-

Regular keylogger
– Here keystrokes in logged in by means of a hardware device attached
between computer and keyboard and it is not dependent upon operating
system of computer thus does not interfere any program running on the
target machine.

Firmware – It is a computer
BIOS responsible for handling keystrokes and can be reprogrammed in
order to record keystrokes and to posses them.

Wireless sniffers
– It collects the packet of data transferring from wireless keyboard to
computer or receiver and then crack the encryption key in order to make
the wireless communication secure

Hardware keylogger supports
all sorts of operating system and thus you can use it in any computer at
any time. If you are looking for a simple and fruitful keyloggers then
this will be the best choice for you.