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Date: Tue, 6 Feb 2024 22:46:59 +0100 (CET)
From: Mikulas Patocka <mpatocka@redhat.com>
To: Herbert Xu <herbert@gondor.apana.org.au>, 
    "David S. Miller" <davem@davemloft.net>
cc: linux-crypto@vger.kernel.org, dm-devel@lists.linux.dev
Subject: A question about modifying the buffer under authenticated
 encryption
Message-ID: <f22dae2c-9cac-a63-fff-3b0b7305be6@redhat.com>
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Hi

I'm trying to fix some problems in dm-crypt that it may report 
authentication failures when the user reads data with O_DIRECT and 
modifies the read buffer while it is being read.

I'd like to ask you:

1. If the authenticated encryption encrypts a message, reading from 
   buffer1 and writing to buffer2 - and buffer1 changes while reading from 
   it - is it possible that it generates invalid authentication tag?

2. If the authenticated encryption decrypts a message, reading from 
   buffer1 and writing to buffer2 - and buffer2 changes while writing to 
   it - is is possible that it reports authentication tag mismatch?

Mikulas