WhatsApp end-to-end encrypted backups security assessment

Re:WhatsApp end-to-end encrypted backups security assessment by richardwhiuk on Thursday November 11, 2021 @06:10AM (#29186727)

The standard fix to this is to give each message a GUID, and then when you delete a message, instead of deleting it, your store a tombstone with the GUID, and that prevents a network re-send from causing the message to reappear.

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Re:WhatsApp end-to-end encrypted backups security assessment by texasbigdata on Thursday November 11, 2021 @06:31AM (#29186849)

Sorry, what’s a tombstone? Like add a field that says “deleted”?

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Re:WhatsApp end-to-end encrypted backups security assessment by Toutouxc on Thursday November 11, 2021 @07:57AM (#29187397)

Yes, it's a concept used e.g. in hash tables that use open addressing [0], where you can't delete value X because the final address of value Y may depend on whether X was present when it was being inserted. So instead of deleting X and leaving behind an empty address we change X to a tombstone that stays there forever and says "something was here and if you're looking for Y, Z or anything else, keep on looking".

[0] https://en.wikipedia.org/wiki/Hash_table#Open_addressing

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Re:WhatsApp end-to-end encrypted backups security assessment by texasbigdata on Thursday November 11, 2021 @04:59PM (#29193727)

Thank you

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Re:WhatsApp end-to-end encrypted backups security assessment by intricatedetail on Thursday November 11, 2021 @07:17AM (#29187119)

Or store message encrypted and corresponding key, then just delete the key.

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