Quoting Sandy Harris <sandyinchina@xxxxxxxxx>:
On Wed, Jun 27, 2012 at 12:13 AM, Sebastian Andrzej Siewior
<sebastian@xxxxxxxxxxxxx> wrote:
Since commit ce6dd368 ("crypto: arc4 - improve performance by adding
ecb(arc4)) we need to pull in a blkcipher.
|ERROR: "crypto_blkcipher_type" [crypto/arc4.ko] undefined!
|ERROR: "blkcipher_walk_done" [crypto/arc4.ko] undefined!
|ERROR: "blkcipher_walk_virt" [crypto/arc4.ko] undefined!
Signed-off-by: Sebastian Andrzej Siewior <sebastian@xxxxxxxxxxxxx>
---
On a side note: do we pull in the blkcipher block mode for each
cipher now to
gain some extra performance like the openssl project? I was under the
impression that is in general not worth it.
Arc4 is a stream cipher, NOT a block cipher. They are completely different
things, and the requirements for using them securely are different. In
particular, modes like ECB apply to block ciphers not to stream ciphers.
Unless these changes have been thoroughly analyzed by several
people who actually know crypto, they should be immediately reverted.
The 'arc4' is defined as one-byte cipher (that modifies its context to
remember current stream state) and ecb module is just used to make
arc4 iterate throught variable length buffers. 'ecb(arc4)' is then the
actual stream cipher, with confusing and wrong name. I guess now that
'ecb(arc4)' is moved to arc4 module completely, it could be renamed to
'arc4stream' and in-kernel arc4 users which to use that.
-Jussi
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