Commit 41952551 authored by Eric Biggers's avatar Eric Biggers
Browse files

fscrypt: add additional documentation for SM4 support 



Add a paragraph about SM4, like there is for the other modes.

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Reviewed-by: default avatarTianjia Zhang <tianjia.zhang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20221201191452.6557-1-ebiggers@kernel.org
parent f8b435f9

Documentation/filesystems/fscrypt.rst

+6 −0
Original line number Diff line number Diff line
@@ -370,6 +370,12 @@ CONFIG_CRYPTO_HCTR2 must be enabled. Also, fast implementations of XCTR and 
POLYVAL should be enabled, e.g. CRYPTO_POLYVAL_ARM64_CE and

CRYPTO_AES_ARM64_CE_BLK for ARM64.



SM4 is a Chinese block cipher that is an alternative to AES.  It has

not seen as much security review as AES, and it only has a 128-bit key

size.  It may be useful in cases where its use is mandated.

Otherwise, it should not be used.  For SM4 support to be available, it

also needs to be enabled in the kernel crypto API.



New encryption modes can be added relatively easily, without changes

to individual filesystems.  However, authenticated encryption (AE)

modes are not currently supported because of the difficulty of dealing