crypto: rsa - add a new rsa generic implementation

Add a new rsa generic SW implementation.
This implements only cryptographic primitives.

Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>

Added select on ASN1.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/crypto/internal/rsa.h

@@ -0,0 +1,27 @@
+/*
+ * RSA internal helpers
+ *
+ * Copyright (c) 2015, Intel Corporation
+ * Authors: Tadeusz Struk <tadeusz.struk@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+#ifndef _RSA_HELPER_
+#define _RSA_HELPER_
+#include <linux/mpi.h>
+
+struct rsa_key {
+	MPI n;
+	MPI e;
+	MPI d;
+};
+
+int rsa_parse_key(struct rsa_key *rsa_key, const void *key,
+		  unsigned int key_len);
+
+void rsa_free_key(struct rsa_key *rsa_key);
+#endif