Law enforcement and intelligence agencies want to be able to wiretap social media, instant message and chat services. But building in ways to wiretap these kinds of communication can lead to less secure systems, say technical experts, including former National Security Agency officials.

Some security experts suggest hacking as an alternative, but other experts – including FBI officials -- say that method poses serious risks.

Right now, only phone companies, broadband providers and some Internet phone services are required by law to build in intercept capabilities, but the government wants to extend that requirement to online communication providers.

“From a purely technical perspective, when you add this sort of law enforcement access feature to a system, you weaken it,” said Steven M. Bellovin, a computer science professor at Columbia University. “First, it creates an access point that previously didn’t exist. Second, you’ve added complexity to the system ... and most security problems are due to buggy code.”

In 1994, the government passed the Communications Assistance for Law Enforcement Act, which mandated that phone companies make their systems wiretap-ready.

Richard “Dickie” George, a former NSA technical director until he retired in September 2011, recalled how in the mid-1990s, “in the early days of CALEA,” the NSA tested several commercial phone systems with intercept capabilities and “we found problems in every one.” Making the systems hack-proof, he said, “is really, really hard.”

He said, however, that over the years, “We’ve come a long way.”

Susan Landau, a faculty member in the Worcester Polytechnic Institute Department of Social Science and Policy Studies in Massachusetts, said that phone services are more complicated now -- and so the switches are, too. “It’s highly doubtful,” she said, “that the new switches are secure.”

The United States, she said, “has a lot more to lose by building ways into communications networks than it has to gain, because those ways last for a very long time, and we enable others who couldn’t afford to build [backdoors] in themselves with ways to get into our communications systems.”

One alternative to wiretaps is to hack the target’s phone or computer, Bellovin and Landau said. In so doing, the FBI would be exploiting software flaws that already exist instead of creating new ones, Landau said. And the FBI would be getting communications before they are encrypted or after they are decrypted, Bellovin said.

“They have to be very careful that they don’t create a risk that the exploit will proliferate elsewhere,” Landau said. “That’s why we argue for increasing the funding for research.”

Marcus Thomas, a former FBI official who ran the bureau’s Operational Technology Division, said hacking is “unreliable and dangerous because hacks can propagate.”

Some tech-savvy privacy advocates say that the government sees the use of malware as one among a number of options, along with weakening the security of commercial software and forcing companies to allow the installation of malware delivery devices on their networks. “The government wants a selection of tools, not just one,” said American Civil Liberties Union principal technologist Christopher Soghoian.

Forcing companies to put malware on a suspect’s cellphone, say by using security update features for mobile users, may lead “privacy aware” consumers to turn off automatic security updates, Soghoian said. “We don't want to give consumers any reason to not update their software.”

He added that “by blessing the malware approach, Landau et al. ... are giving DOJ political cover” to use malware.

The FBI has in fact applied for search warrants to use the technique in several recent criminal cases.

But FBI officials said in an interview that hacking is not commonly used on the criminal side of the Justice Department. "It is rare in law enforcement investigations," said Amy S. Hess, executive assistant director of the FBI’s Science and Technology Branch. She did not comment on how often it might be used in intelligence investigations.

She said the capability is “very fragile.” It changes, “minute by minute, hour by hour, day to day, as to whether or not you’re able to stay up on that particular device just because of the changing nature of technology.” Moreover, she said, “a lot of bad guys trade off devices. So how valuable will it be if you have to keep doing that type of procedure over and over again?”

She noted it is also at “much higher risk” of detection if it is disclosed in a criminal case.

On Thursday, Scott Charney, Microsoft vice president of trustworthy computing, said that the government has never asked the company to change its code or alter its products to give it access to Skype, which is owned by Microsoft. “If they said ... put in a backdoor, we would fight it all the way to the Supreme Court,” he said during a panel session at the Aspen Security Forum. “If the government did that, and I really don’t think they would, it would be at the complete expense of American competitiveness, because if we put in a backdoor for the U.S. government, we couldn’t sell anywhere in the world. Not even in America.”