PKCS#7: Implement a parser [RFC 2315]

Implement a parser for a PKCS#7 signed-data message as described in part of
RFC 2315.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h
index 6926db7..edeff85 100644
--- a/include/linux/oid_registry.h
+++ b/include/linux/oid_registry.h
@@ -55,6 +55,7 @@
 	OID_certAuthInfoAccess,		/* 1.3.6.1.5.5.7.1.1 */
 	OID_msOutlookExpress,		/* 1.3.6.1.4.1.311.16.4 */
 	OID_sha1,			/* 1.3.14.3.2.26 */
+	OID_sha256,			/* 2.16.840.1.101.3.4.2.1 */
 
 	/* Distinguished Name attribute IDs [RFC 2256] */
 	OID_commonName,			/* 2.5.4.3 */