[CRYPTO] lib: table driven multiplications in GF(2^128)

A lot of cypher modes need multiplications in GF(2^128). LRW, ABL, GCM...
I use functions from this library in my LRW implementation and I will
also use them in my ABL (Arbitrary Block Length, an unencumbered (correct
me if I am wrong, wide block cipher mode).

Elements of GF(2^128) must be presented as u128 *, it encourages automatic
and proper alignment.

The library contains support for two different representations of GF(2^128),
see the comment in gf128mul.h. There different levels of optimization
(memory/speed tradeoff).

The code is based on work by Dr Brian Gladman. Notable changes:
- deletion of two optimization modes
- change from u32 to u64 for faster handling on 64bit machines
- support for 'bbe' representation in addition to the, already implemented,
  'lle' representation.
- move 'inline void' functions from header to 'static void' in the
  source file
- update to use the linux coding style conventions

The original can be found at:
http://fp.gladman.plus.com/AES/modes.vc8.19-06-06.zip

The copyright (and GPL statement) of the original author is preserved.

Signed-off-by: Rik Snel <rsnel@cube.dyndns.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 10 insertions, 0 deletions

diff --git a/crypto/Kconfig b/crypto/Kconfig
index 4495e46660bf..f941ffb2a087 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -139,6 +139,16 @@ config CRYPTO_TGR192
           See also:
           <http://www.cs.technion.ac.il/~biham/Reports/Tiger/>.
 
+config CRYPTO_GF128MUL
+        tristate "GF(2^128) multiplication functions (EXPERIMENTAL)"
+        depends on EXPERIMENTAL
+        help
+          Efficient table driven implementation of multiplications in the
+          field GF(2^128).  This is needed by some cypher modes. This
+          option will be selected automatically if you select such a
+          cipher mode.  Only select this option by hand if you expect to load
+          an external module that requires these functions.
+
 config CRYPTO_ECB
         tristate "ECB support"
         select CRYPTO_BLKCIPHER