gcc 8.3.0 was apparently clever enough to optimize away the previously
used os_memset() to explicitly clear a stack buffer that contains keys
when that clearing happened just before returning from the function.
Since memset_s() is not exactly portable (or commonly available yet..),
use a less robust mechanism that is still pretty likely to prevent
current compilers from optimizing the explicit clearing of the memory
away.
Signed-off-by: Jouni Malinen <j@w1.fi>
The KDF define in RFC 5295 is very similar to HKDF-Expand() defined in
RFC 5869. Allow a NULL label to be used to select the RFC 5869 version
with arbitrary seed (info in RFC 5869) material without forcing the
label and NULL termination to be included. HKDF-Expand() will be needed
for OWE.
Signed-off-by: Jouni Malinen <j@w1.fi>
The local T[] buffer may contain parts of the derived key, so clear it
explicitly to minimize number of unnecessary copies of key material in
memory.
Signed-off-by: Jouni Malinen <j@w1.fi>
