crypto,fs: Separate out hkdf_extract() and hkdf_expand()

Separate out the HKDF functions into a separate module to
to make them available to other callers.
And add a testsuite to the module with test vectors
from RFC 5869 (and additional vectors for SHA384 and SHA512)
to ensure the integrity of the algorithm.

Signed-off-by: Hannes Reinecke <[email protected]>
Acked-by: Eric Biggers <[email protected]>
Acked-by: Herbert Xu <[email protected]>
Signed-off-by: Keith Busch <[email protected]>

Author: Hannes Reinecke

crypto/Kconfig

@@ -141,6 +141,12 @@ config CRYPTO_ACOMP
 	select CRYPTO_ALGAPI
 	select CRYPTO_ACOMP2
 
+config CRYPTO_HKDF
+	tristate
+	select CRYPTO_SHA256 if !CONFIG_CRYPTO_MANAGER_DISABLE_TESTS
+	select CRYPTO_SHA512 if !CONFIG_CRYPTO_MANAGER_DISABLE_TESTS
+	select CRYPTO_HASH2
+
 config CRYPTO_MANAGER
 	tristate "Cryptographic algorithm manager"
 	select CRYPTO_MANAGER2

crypto/Makefile

@@ -34,6 +34,7 @@ obj-$(CONFIG_CRYPTO_HASH2) += crypto_hash.o
 obj-$(CONFIG_CRYPTO_AKCIPHER2) += akcipher.o
 obj-$(CONFIG_CRYPTO_SIG2) += sig.o
 obj-$(CONFIG_CRYPTO_KPP2) += kpp.o
+obj-$(CONFIG_CRYPTO_HKDF) += hkdf.o
 
 dh_generic-y := dh.o
 dh_generic-y += dh_helper.o