w3c / w3c/webcrypto

Crypto needs defensive deep-copy constructor

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Description

According to https://developer.mozilla.org/en-US/docs/Web/API/Window/crypto:

"Although the Window.crypto property iteself is read-only, all of its methods (and the methods of its child object, SubtleCrypto) are not read-only, and therefore vulnerable to attack by polyfill."

If the Crypto class had a copying constructor that also replaced the SubtleCrypto with a defensive deep copy, it would be possible to prevent this attack by using a defensive copy of the Crypto object that was made before any untrusted polyfills were loaded.

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Research direction

Start by locating the Crypto class and its SubtleCrypto child object, then review how their methods and properties can be modified after construction. Determine the required defensive-copy semantics and how a copy made before polyfills are loaded should behave. Done means the proposed constructor and its tests demonstrate that later changes to the original objects cannot affect the defensive copy.

Written by the indexing model from the issue text.

Assessment

Domain
security
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
30/100

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