Computer-infection software can help agents read scrambled data.

The FBI is developing new surveillance software that would allow agents to decode the hard-to-break encrypted data of criminal suspects, MSNBC reported Wednesday.

Many tech-savvy criminals encrypt their electronic communications to evade law enforcement. Known as "Magic Lantern," the FBI's new software is designed to eliminate this digital loophole.

Magic Lantern works by infecting a suspect's computer with a virus that installs "keylogging" software -- a program that can capture the keystrokes typed into a computer. If agents can track what a suspect types, they could obtain information that would let them access the key a suspect uses to encrypt and decrypt data.

That's because encryption keys are protected only by the pass phrase used to start the Pretty Good Privacy program, similar to the passwords used to control access to a network. If agents can decipher a suspect's pass phrase by examining what he types into his computer, they can gain access to his encryption keys. The keys can then be used to unscramble the suspect's encrypted messages.

To infect a suspect's computers with the keylogging virus, the FBI could enlist a suspect's friends or relatives to email the virus inside an attachment, a source told MSNBC. The FBI could also infect a target computer by exploiting known security vulnerabilities, the source said.

According to MSNBC's source, Magic Lantern is one of a series of enhancements the FBI is currently making to its Carnivore project, the name given to the agency's email-spying tool.