Nowadays, security problems are rarely properly solved or correctly addressed. Electronic security is only part of the chain in making a system secure. Electronic security is usually addressed as network or software security, neglecting other aspects, but the chain is only as strong as its weakest link.This book is about electronic hardware security, with an emphasis on problems that you can solve on a shoestring DIY budget. It deals mostly with secure communications, cryptosystems, and espionage. You will quickly appreciate that you can’t simply buy a trustworthy and reliable cryptosystem off the shelf. You will then realise that this applies equally to individuals, corporations, and governments.If you want to increase your electronic security awareness in a world already overcrowded with networks of microphones and cameras, this is a book for you. Furthermore, if you want to do something DIY by designing and expanding upon simple electronic systems, please continue reading. Some of the devices described are already published as projects in the Elektor magazine. Some are still ideas yet to be worked out.Complexity is the main enemy of security, so we'll try to keep to simple systems. Every chapter will analyse real-life espionage events or at least several hypothetical scenarios that will hopefully spark your imagination. The final goal is to build a security-conscious mindset (or “to get into a head of a spy”) which is necessary to recognise possible threats beforehand, to design a truly secure system.