fscrypt: add additional documentation for SM4 support

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

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20221201191452.6557-1-ebiggers@kernel.org
This commit is contained in:
Eric Biggers 2022-12-01 11:14:52 -08:00
parent f8b435f93b
commit 41952551ac

View file

@ -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