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NSA Says Its Secure Dev Methods Are Publicly Known
Trailrunner7 writes "Despite its reputation for secrecy and technical expertise, the National Security Agency doesn't have a set of secret coding practices or testing methods that magically make their applications and systems bulletproof. In fact, one of the agency's top technical experts said that virtually all of the methods the NSA uses for development and information assurance are publicly known. 'Most of what we do in terms of app development and assurance is in the open literature now. Those things are known publicly now,' Neil Ziring, technical director of the NSA's Information Assurance Directorate, said in his keynote at the OWASP AppSec conference in Washington Wednesday. 'It used to be that we had some methods and practices that weren't well-known, but over time that's changed as industry has focused more on application security.'"
Writing bulletproof code isn't really all that hard, but it does take discipline. Discipline to use only those constucts which have been verified with both the compiler and linker.
Some simple things that coders can do: - avoid the use of pointers.
Pointers aren't themselves bad; they just add some layers of complication to the otherwise stack-oriented game. The only reason the stack is nicer than pointers is because they're implicitly managed for you.
Rather than avoid pointers, what you need is good code structure. Design functions that either manage the lifecycle of a pointer or are explicitly clear about how and what the pointer is going to be used as. Use const aggressively, and avoid typecasting as much as possible. Using good pointer naming techniques and management functions also dissipate the burden. Pointers are too useful to avoid religiously ... rather, build pointer security and management techniques into your coding style from the ground up. Choose descriptive names and try and constrain each pointer to its specific type (this lets the compiler help you keep your pointers straight).
Initialize all variables to known values.
Meh, I'm divided on this one. It's one thing to explicitly initialize global variables to either zero (which costs nothing, since they just end up in BSS sections) or non-zero (which puts them statically in the data segment). Stack variables, on the other hand, only really need to be initialized before they're used the first time. Pre-initializing them could lead to wasted instructions initializing them multiple times or cause them to be initialized in all code paths when they're only used in a few. My general rule of thumb is to be smart about it and, once again, naming conventions.
Perform comparisons with the LHS using a static variable, so you don't accidentally get an assignment instead of a comparison
Great tip; it's weird at first writing "if( NULL != p )", and you get a few funny stares, but after seeing enough "if( i = 10 )"s lying within seemingly-functional code, it's an easy selling point to make.
- When you are done with a value, reset it to a "known" value. Zero is usually good.
Definitely do this with pointers, descriptors, and other handle types. It also makes cleanup and pointer management easier. Less important to do with things like iterators and intermediate variables.
- Keep functions less than 1 page long. If you can't see the entire function on a single editor page, it is too long.
It's a good rule of thumb. I would like to add "any time you can't do this, make absolutely certain that you're not doing it for a good reason."
Good tips, though. One thing I'd like to add: -Wall -Wextra -Werror (or your language's equivalent). If your code can't compile without a single warning, then you need to re-write your code and either manually disarm situations (e.g., override the compiler's common-sense with an assurance that you know what you're doing) or fix the warnings, which are actually bugs and errors. It's always fun to take someone's "bulletproof" code and turn on these flags and watch the crap spill out. Warnings are amazing, and they are absolutely your friend when it comes to writing bug-free and secure code.