Re: using crypto_digest() on non-kmalloc'd memory failures

From: Oleg Makarenko
Date: Tue Oct 19 2004 - 00:42:48 EST


James Morris wrote:

On Tue, 19 Oct 2004, Oleg Makarenko wrote:


Is there any better way to use crypto api for arc4 or similar ciphers? Cipher block size is not always a natural choice for the crypto_yield(). Especially for fast ciphers (arc4) and small "block" sizes (arc4 again).



ARC4 is a bit strange because it's a stream cipher. I guess we could add another encryption mode 'stream' which is optimized for one byte at a time operation.


- James


That would probably require one more parameter to cin_encrypt/cia_decrypt, something like "nblocks" which currently is always 1 and one more struct crypto_alg field that would help upper level to decide how many blocks it can safely encrypt/decrypt() at a time before crypto_yield(). This value depends on algorithm speed and should be chosen to make overhead smaller. It could be > 1 even for fast block ciphers and should be > 1 for stream ciphers.

=oleg



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