Wrong prefix match

[sualko]

libsignal-protocol-javascript/src/helpers.js

Lines 35 to 47 in f5a838f

	isEqual: function(a, b) {
	// TODO: Special-case arraybuffers, etc
	if (a === undefined || b === undefined) {
	return false;
	}
	a = util.toString(a);
	b = util.toString(b);
	var maxLength = Math.max(a.length, b.length);
	if (maxLength < 5) {
	throw new Error("a/b compare too short");
	}
	return a.substring(0, Math.min(maxLength, a.length)) == b.substring(0, Math.min(maxLength, b.length));
	}

I think someone tried here to implement a prefix match, but it should not work, because it's the same as

return a.substring(0, a.length) == b.substring(0, b.length);

Am I right, or did I overlook something? Are you interested in a pr?

[elsehow]

I am definitely up for a PR!

In the PR, be sure to make a test that:

• Fails as it's written currently
• Explains why the test should pass
• Passes with your propose implementation

Thank you for reviewing the code!

[sualko]

The problem is, that I'm not sure if the intended behavior is that this is a prefix match. It would be awesome if a developer could give a hint.

[elsehow]

@sualko Indeed. Unfortunately, this code all comes from the libsignal-javascript project.