diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 7092d5c..9e9e5a6 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -13,11 +13,15 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/mpi.h>
+#include <linux/asn1_decoder.h>
 #include <keys/asymmetric-subtype.h>
 #include <keys/asymmetric-parser.h>
 #include <keys/system_keyring.h>
 #include <crypto/hash.h>
 #include "asymmetric_keys.h"
+#include "public_key.h"
 #include "x509_parser.h"
 
 static bool use_builtin_keys;
@@ -163,15 +167,13 @@
 
 	if (cert->unsupported_crypto)
 		return -ENOPKG;
-	if (cert->sig.s)
+	if (cert->sig.rsa.s)
 		return 0;
 
-	cert->sig.s = kmemdup(cert->raw_sig, cert->raw_sig_size,
-			      GFP_KERNEL);
-	if (!cert->sig.s)
+	cert->sig.rsa.s = mpi_read_raw_data(cert->raw_sig, cert->raw_sig_size);
+	if (!cert->sig.rsa.s)
 		return -ENOMEM;
-
-	cert->sig.s_size = cert->raw_sig_size;
+	cert->sig.nr_mpi = 1;
 
 	/* Allocate the hashing algorithm we're going to need and find out how
 	 * big the hash operational data will be.
@@ -294,6 +296,8 @@
 	if (cert->pub->pkey_algo >= PKEY_ALGO__LAST ||
 	    cert->sig.pkey_algo >= PKEY_ALGO__LAST ||
 	    cert->sig.pkey_hash_algo >= PKEY_HASH__LAST ||
+	    !pkey_algo[cert->pub->pkey_algo] ||
+	    !pkey_algo[cert->sig.pkey_algo] ||
 	    !hash_algo_name[cert->sig.pkey_hash_algo]) {
 		ret = -ENOPKG;
 		goto error_free_cert;
@@ -305,6 +309,7 @@
 		 pkey_algo_name[cert->sig.pkey_algo],
 		 hash_algo_name[cert->sig.pkey_hash_algo]);
 
+	cert->pub->algo = pkey_algo[cert->pub->pkey_algo];
 	cert->pub->id_type = PKEY_ID_X509;
 
 	/* Check the signature on the key if it appears to be self-signed */