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The case against rolling your own crypto is that bugs can hide in crypto software without symptoms. Everything will seem to function perfectly. The verifier wi

The case against rolling your own crypto is that bugs can hide in crypto software without symptoms. Everything will seem to function perfectly. The verifier will o.k. valid signatures and reject invalid ones. The signatures themselves will look like gibberish to the eye. But the bug will still be there, waiting for an actual attack.

commandlinefan 8y ago
Unless you do it right.
- Djvacto 8y ago
  The issue with this is the same thing that happens with all sorts of data breaches, regardless of whether it was caused by negligence. Of course there's no problem if you do it right. It's just that guaranteeing you did it right is never possible with 100% certainty if you wrote the code, evaluated the code, and published the code. More eyes means less mistakes. More hands makes less work. If you roll your own templating system, and you mess up, then some text on a page is displayed wrong. If you roll your own crypto to protect customer data and you mess up, whoops, that customer data is out there.
- Bartweiss 8y ago
  I agree that people are often too zealous about "don't do it yourself", whether in the name of security or preventing duplicate work. md5 hashing unsalted passwords is bad, but so is critically misconfiguring an off-the-shelf password tool you didn't understand. Not Invented Here Syndrome is bad, but so is breaking the entire internet because you didn't want to write 20 lines of NPM left-pad yourself. That said, I think there's still a major difference between roll-your-own-crypto and other "unless you do it right" topics. Securely storing passwords and preventing XSS are things that can look ok and be insecure unless you do it right, but I'm not (always) against people (carefully) handling those things themselves. Rolling your own signatures or encryption are infamous because a "best practices" list and good code review won't save you; even if you root out all the actual bugs, your process can still be cripplingly vulnerable. As Schneier said, anyone can create an alogorithm they can't compromise.
- emiliobumachar 8y ago
  Did you ever typo a character in your code and didn't notice, causing a fast compile or runtime error, then promptly fixed it? If it had compiled and ran with no visible symptoms, would you ever catch that typo? That's the level of gotcha in rolling your own crypto.
- coldtea 8y ago
  Yeah, sort of like playing the lottery is a bad investment, unless you win.

commandlinefan 8y ago

Unless you do it right.

Djvacto 8y ago
The issue with this is the same thing that happens with all sorts of data breaches, regardless of whether it was caused by negligence. Of course there's no problem if you do it right. It's just that guaranteeing you did it right is never possible with 100% certainty if you wrote the code, evaluated the code, and published the code. More eyes means less mistakes. More hands makes less work. If you roll your own templating system, and you mess up, then some text on a page is displayed wrong. If you roll your own crypto to protect customer data and you mess up, whoops, that customer data is out there.
Bartweiss 8y ago
I agree that people are often too zealous about "don't do it yourself", whether in the name of security or preventing duplicate work. md5 hashing unsalted passwords is bad, but so is critically misconfiguring an off-the-shelf password tool you didn't understand. Not Invented Here Syndrome is bad, but so is breaking the entire internet because you didn't want to write 20 lines of NPM left-pad yourself. That said, I think there's still a major difference between roll-your-own-crypto and other "unless you do it right" topics. Securely storing passwords and preventing XSS are things that can look ok and be insecure unless you do it right, but I'm not (always) against people (carefully) handling those things themselves. Rolling your own signatures or encryption are infamous because a "best practices" list and good code review won't save you; even if you root out all the actual bugs, your process can still be cripplingly vulnerable. As Schneier said, anyone can create an alogorithm they can't compromise.
emiliobumachar 8y ago
Did you ever typo a character in your code and didn't notice, causing a fast compile or runtime error, then promptly fixed it? If it had compiled and ran with no visible symptoms, would you ever catch that typo? That's the level of gotcha in rolling your own crypto.
coldtea 8y ago
Yeah, sort of like playing the lottery is a bad investment, unless you win.