core: crypto: add support for SM4

Adds support for the SM4 cipher [1] using the API defined in the
GlobalPlatform TEE Internal Core API v1.2.

ECB, CBC and CTR modes are implemented. Other modes are

core: crypto: add support for SM4

Adds support for the SM4 cipher [1] using the API defined in the
GlobalPlatform TEE Internal Core API v1.2.

ECB, CBC and CTR modes are implemented. Other modes are valid but are
not included in the GP specification, so they are not considered here.

This implementation is based on code published on Gitlab [2]. The
project contains no licensing terms, so I contacted the author
(goldboar@163.com), asking for permission to re-use the code in OP-TEE
under a BSD-2-Clause license. I received the following reply:

"[...] If you like you can use it [...]"

I have reworked the source to better fit the OP-TEE coding style. I
have also added the CTR mode of operation.

I do not think we will need to merge any change from upstream in the
future.

[1] https://tools.ietf.org/html/draft-ribose-cfrg-sm4-10
[2] https://gitlab.com/otpfree/sm234

Signed-off-by: Jerome Forissier <jerome@forissier.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Acked-by: Etienne Carriere <etienne.carriere@linaro.org>

show more ...