Modify public_key_verify_signature() so that it now takes a public_key struct
rather than a key struct and supply a wrapper that takes a key struct.  The
wrapper is then used by the asymmetric key subtype and the modified function is
used by X.509 self-signature checking and can be used by other things also.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NJosh Boyer <jwboyer@redhat.com>

Implement RSA public key cryptography [PKCS#1 / RFC3447].  At this time, only
the signature verification algorithm is supported.  This uses the asymmetric
public key subtype to hold its key data.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Add a subtype for supporting asymmetric public-key encryption algorithms such
as DSA (FIPS-186) and RSA (PKCS#1 / RFC1337).
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>