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doc: add note about timingSafeEqual for TypedArray #36323

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doc: add note about timingSafeEqual for TypedArray #36323

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doc: add note about timingSafeEqual for TypedArray
tniessen Nov 30, 2020
dd16890
fixup
tniessen Dec 12, 2020
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5 changes: 4 additions & 1 deletion doc/api/crypto.md
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Expand Up @@ -3383,7 +3383,10 @@ comparing HMAC digests or secret values like authentication cookies or
[capability urls](https://www.w3.org/TR/capability-urls/).

`a` and `b` must both be `Buffer`s, `TypedArray`s, or `DataView`s, and they
must have the same length.
must have the same byte length.

If at least one of `a` and `b` is a `TypedArray`, the result may depend on
the platform byte order.
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may depend sounds like this isn’t deterministic, but I assume it is? It’s always going to depend on the platform byte order, right?

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Good point! My thinking was that the result of some inputs (e.g., timingSafeEqual(new Uint8Array([1, 1]), new Uint16Array([0x0101]))) does not depend on the platform byte order, but that's probably not what others would take away from the way I worded it.

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Yeah, I see … maybe I would say something like If at least one of `a` and `b` is a `TypedArray` with more than one byte per entry, like `Uint16Array`, the result will be computed using platform byte order?

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Sorry about the delay, fixed!


Use of `crypto.timingSafeEqual` does not guarantee that the *surrounding* code
is timing-safe. Care should be taken to ensure that the surrounding code does
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