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posted by martyb on Saturday December 02 2017, @01:48PM   Printer-friendly
from the see-what-we-did-there? dept.

https://www.cossacklabs.com/blog/macros-in-crypto-c-code.html

Like death and taxes, one thing that you can be sure of is that using C macros in a modern software project will cause a debate. While for some macros remain a convenient and efficient way of achieving particular programming goals, for others they are opaque, introduce the unnecessary risk of coding errors, and reduce readability.

The criticism of macros is particularly acute in the wider security community. Among Cossack Labs' engineers and the core Themis crypto library contributors there are people who previously worked on auditing cryptographic implementations of critical code. Their typical knee-jerk reaction to macros was always "kill it with fire and never use it again". Taking no sides, we would like to assess both pros and cons of using such dangerous things as macros in security code (as we faced the issue when developing Themis) and suggest some techniques for lowering the accompanying risks.

We'll also discuss a custom "for-audit" build target for Themis designed specifically to generate source code that exposes the macros to inspection because we appreciate the need for security software to be subject to detailed source code scrutiny.


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  • (Score: 2) by The Mighty Buzzard on Sunday December 03 2017, @02:24AM

    by The Mighty Buzzard (18) Subscriber Badge <themightybuzzard@proton.me> on Sunday December 03 2017, @02:24AM (#604524) Homepage Journal

    You're entitled to your opinion. I just hope I never have to come behind and fix any of your code.

    I'd argue overly verbose commenting, like "expand the macro in a comment" does more to reduce readability...

    Yeah, that would only be a problem if you can't read the code well. If you understand what you're looking at, seeing the actual code adds clarity instead of removes it. If you don't, you need to step back from the keyboard and hand the project off to someone who does.

    --
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