Question

strategies and word patterns: the code book
the code book: the science of secrecy from ancient egypt to quantum cryptography
other attacks include the use of viruses and trojan horses. eve might design a virus that infects pgp software and sits quietly inside alices computer. when alice uses her private key to decrypt a message, the virus would wake up and make a note of it. the next time that alice connects to the internet, the virus would surreptitiously send the private key to eve, thereby allowing her to decipher all subsequent messages sent to alice. the trojan horse, another software trick, involves eve designing a program that appears to act like a genuine encryption product, but which actually betrays the user.
—the code book,
simon singh
what is the central idea of the passage?
no one should ever use pgp software or viruses.
people can invade your internet privacy even if you code your information.
the trojan horse is a really clever way to invade someones privacy.
alice should find a new way to send her private

Explanation:

The passage describes how viruses and Trojan - horses can be used to invade Internet privacy by stealing private keys or betraying users, showing that privacy can be invaded even when information is coded.

Answer:

People can invade your Internet privacy even if you code your information.