Black-Bag Cryptanalysis

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In cryptography, black-bag cryptanalysis is a euphemism for the acquisition of cryptographic secrets via burglary, or the covert installation of keystroke logging or trojan horse software/hardware on target computers or ancillary devices. It is even possible to monitor the electromagnetic emissions of computer displays or keyboards from a distance of 20 metres (or more), and thereby decode what has been typed. This could be done by surveillance technicians, or via some form of bug concealed somewhere in the room. Although sophisticated technology is often used, black bag cryptanalysis can also be as simple as the process of copying a password which someone has unwisely written down on a piece of paper and left inside their desk drawer.