Re: [dm-crypt] cryptsetup with arc4 cipher

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Sebastian Andrzej Siewior <linux-crypto@xxxxxxxxxxxxxxxx> wrote:
> 
> The long story:
> ARC4 is a stream cipher and not a block cipher. Its internal state is
> reseted in setkey() and every crypto request (encrypt/decrypt don't
> matter) update the internal state of the stream cipher. That's why you
> get a different result every time you read the same block.

Actually I think that's a bug.  These ciphers really should not
modify their tfm state between operations.  Requiring a setkey
before each new operation precludes parallel processing.

I noticed that salsa seems to be broken in the same way, but at
least it should be easy to fix.

arc4 on the other hand needs to be converted to a blkcipher.

Cheers,
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