Because NSA is chartered with assisting the USG and, as a knock-on effect, the US economy, with infosec. It's part of their job. Just like designing secure ciphers is part of their job, along with breaking them.
"Even agency programs ostensibly intended to guard American communications are sometimes used to weaken protections. The N.S.A.’s Commercial Solutions Center, for instance, invites the makers of encryption technologies to present their products and services to the agency with the goal of improving American cybersecurity. But a top-secret N.S.A. document suggests that the agency’s hacking division uses that same program to develop and “leverage sensitive, cooperative relationships with specific industry partners” to insert vulnerabilities into Internet security products. "
Actual quote from the CTO of a company that makes some security-related software (it's a major selling point) for a specific sector. They probably have over a hundred million people using this stuff day-to-day, indirectly, and hundreds of direct, large customers. Security bypass can easily cost hundreds of thousands a month.
I had found a backdoor in their platform, so I asked if they had such basic holes, how they managed to write a large C-based app securely. Like, buffer overflows, for example.
CTO/head of development replied: "Buffer overflows? Probably not an issue, unless the network is really fast." Cringe.
There's nothing at all opposing about those goals. They're both natural by products of expertise in signals intelligence and cryptanalysis, and skill breaking security helps provide more secure systems by subjecting them to more sophisticated attacks.
Just as a clarification, NSA doesn't set those standards. Agencies like NIST set AES and SHA3 through open worldwide competitions. These standards then become parts of larger compliance guidelines like FIPS (Federal Information Protection Standard I think) that govern how the USG should protect its data.
NIST has like 2 cryptographers, doesn't it? The real guidance at NIST comes from NSA. If you think NSA is backdooring Suite B crypto, you can't trust NIST.
