Microsoft General Counsel Brad Smith, in a July blog post, detailed the way Microsoft responds to court surveillance orders.
"We do not provide any government with direct access to emails or instant messages," Smith wrote then. "Full stop."
CDT's Hall defended Microsoft's approach. "It seems pretty clear that Microsoft is legally compelled to do this and would not otherwise do it voluntarily," he said.
But Matthew Green, a cryptographer and research professor at Johns Hopkins University, suggested Microsoft is due for scrutiny on encryption security, if encryption has been compromised, as the recent news stories suggest. Most commercial encryption code uses a small number of libraries, with Microsoft CryptoAPI being among the most common, he wrote in a blog post.
"While Microsoft employs good (and paranoid!) people to vet their algorithms, their ecosystem is obviously deeply closed-source," Green wrote. "You can view Microsoft's code (if you sign enough licensing agreements) but you'll never build it yourself. Moreover they have the market share. If any commercial vendor is weakening encryption systems, Microsoft is probably the most likely suspect."
Microsoft IIS runs on about 20 percent of the Internet's Web servers, and nearly 40 percent of the SSL servers, while third-party encryption programs running on Windows depend on Microsoft APIs (application programming interfaces), Green noted.
"That makes these programs somewhat dependent on Microsoft's honesty," he said.
The good news for privacy-minded Internet users is that security researchers questioned whether the foundations of cryptography itself have been compromised. Some encryption protocols are vulnerable, but it's likely that the NSA is attacking the software that encryption is implemented with or relying on human mistakes, Green wrote.
"Software is a disaster," he added. "Hardware isn't that much better. Unfortunately active software exploits only work if you have a target in mind. If your goal is mass surveillance, you need to build insecurity in from the start. That means working with vendors to add backdoors."
Any compromises are unlikely to be related to weakness in the underlying cryptography, added Dave Anderson, a senior director at Voltage Security.
"It seems likely that any possible way that the NSA might have bypassed encryption was almost certainly due to a flaw in the key management processes that support the use of encryption, rather than through the cryptography itself," he said by email. "So, is it possible that the NSA can decrypt financial and shopping accounts? Perhaps, but only if the cryptography that was used to protect the sensitive transactions was improperly implemented through faulty, incomplete or invalid key management processes or simple human error."
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