diff --git a/crypto/crypto_null.c b/crypto/crypto_null.c
index f691d31..3fcf6e8 100644
--- a/crypto/crypto_null.c
+++ b/crypto/crypto_null.c
@@ -21,6 +21,7 @@
 #include <linux/mm.h>
 #include <asm/scatterlist.h>
 #include <linux/crypto.h>
+#include <linux/string.h>
 
 #define NULL_KEY_SIZE		0
 #define NULL_BLOCK_SIZE		1
@@ -28,11 +29,13 @@
 
 static int null_compress(void *ctx, const u8 *src, unsigned int slen,
                          u8 *dst, unsigned int *dlen)
-{ return 0; }
-
-static int null_decompress(void *ctx, const u8 *src, unsigned int slen,
-                           u8 *dst, unsigned int *dlen)
-{ return 0; }
+{
+	if (slen > *dlen)
+		return -EINVAL;
+	memcpy(dst, src, slen);
+	*dlen = slen;
+	return 0;
+}
 
 static void null_init(void *ctx)
 { }
@@ -47,11 +50,10 @@
                        unsigned int keylen, u32 *flags)
 { return 0; }
 
-static void null_encrypt(void *ctx, u8 *dst, const u8 *src)
-{ }
-
-static void null_decrypt(void *ctx, u8 *dst, const u8 *src)
-{ }
+static void null_crypt(void *ctx, u8 *dst, const u8 *src)
+{
+	memcpy(dst, src, NULL_BLOCK_SIZE);
+}
 
 static struct crypto_alg compress_null = {
 	.cra_name		=	"compress_null",
@@ -62,7 +64,7 @@
 	.cra_list		=       LIST_HEAD_INIT(compress_null.cra_list),
 	.cra_u			=	{ .compress = {
 	.coa_compress 		=	null_compress,
-	.coa_decompress		=	null_decompress } }
+	.coa_decompress		=	null_compress } }
 };
 
 static struct crypto_alg digest_null = {
@@ -90,8 +92,8 @@
 	.cia_min_keysize	=	NULL_KEY_SIZE,
 	.cia_max_keysize	=	NULL_KEY_SIZE,
 	.cia_setkey		= 	null_setkey,
-	.cia_encrypt		=	null_encrypt,
-	.cia_decrypt		=	null_decrypt } }
+	.cia_encrypt		=	null_crypt,
+	.cia_decrypt		=	null_crypt } }
 };
 
 MODULE_ALIAS("compress_null");