All common block ciphers have a block size that's a power of 2. In fact,
all of our block ciphers obey this rule.
If we require this then CBC can be optimised to avoid an expensive divide
on in-place decryption.
I've also changed the saving of the first IV in the in-place decryption
case to the last IV because that lets us use walk->iv (which is already
aligned) for the xor operation where alignment is required.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch passes the type/mask along when constructing instances of
templates. This is in preparation for templates that may support
multiple types of instances depending on what is requested. For example,
the planned software async crypto driver will use this construct.
For the moment this allows us to check whether the instance constructed
is of the correct type and avoid returning success if the type does not
match.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch adds two block cipher algorithms, CBC and ECB. These
are implemented as templates on top of existing single-block cipher
algorithms. They invoke the single-block cipher through the new
encrypt_one/decrypt_one interface.
This also optimises the in-place encryption and decryption to remove
the cost of an IV copy each round.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
David Howells