[PATCH 1/3] staging: rtl8188eu: Use existing arc4 implementation

From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
To: Larry.Finger@lwfinger.net, gregkh@linuxfoundation.org
Cc: linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org,
	kernel-janitors@vger.kernel.org,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Subject: [PATCH 1/3] staging: rtl8188eu: Use existing arc4 implementation
Date: Sat, 10 Apr 2021 13:54:59 +0200	[thread overview]
Message-ID: <7e16c40d5baa007dca81a12b967a597ed00d8dd7.1618055514.git.christophe.jaillet@wanadoo.fr> (raw)

Use functions provided by <crypto/arc4.h> instead of hand writing them.

The implementations are slightly different, but are equivalent. It has
been checked with a test program which compares the output of the 2 sets of
functions.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/staging/rtl8188eu/core/rtw_security.c | 80 +++----------------
 1 file changed, 11 insertions(+), 69 deletions(-)

diff --git a/drivers/staging/rtl8188eu/core/rtw_security.c b/drivers/staging/rtl8188eu/core/rtw_security.c
index 617f89842c81..61e3eb0a4791 100644
--- a/drivers/staging/rtl8188eu/core/rtw_security.c
+++ b/drivers/staging/rtl8188eu/core/rtw_security.c
@@ -6,6 +6,7 @@
  ******************************************************************************/
 #define  _RTW_SECURITY_C_
 
+#include <crypto/arc4.h>
 #include <osdep_service.h>
 #include <drv_types.h>
 #include <wifi.h>
@@ -16,65 +17,6 @@
 
 #define CRC32_POLY 0x04c11db7
 
-struct arc4context {
-	u32 x;
-	u32 y;
-	u8 state[256];
-};
-
-static void arcfour_init(struct arc4context *parc4ctx, u8 *key, u32	key_len)
-{
-	u32	t, u;
-	u32	keyindex;
-	u32	stateindex;
-	u8 *state;
-	u32	counter;
-
-	state = parc4ctx->state;
-	parc4ctx->x = 0;
-	parc4ctx->y = 0;
-	for (counter = 0; counter < 256; counter++)
-		state[counter] = (u8)counter;
-	keyindex = 0;
-	stateindex = 0;
-	for (counter = 0; counter < 256; counter++) {
-		t = state[counter];
-		stateindex = (stateindex + key[keyindex] + t) & 0xff;
-		u = state[stateindex];
-		state[stateindex] = (u8)t;
-		state[counter] = (u8)u;
-		if (++keyindex >= key_len)
-			keyindex = 0;
-	}
-}
-
-static u32 arcfour_byte(struct arc4context *parc4ctx)
-{
-	u32 x;
-	u32 y;
-	u32 sx, sy;
-	u8 *state;
-
-	state = parc4ctx->state;
-	x = (parc4ctx->x + 1) & 0xff;
-	sx = state[x];
-	y = (sx + parc4ctx->y) & 0xff;
-	sy = state[y];
-	parc4ctx->x = x;
-	parc4ctx->y = y;
-	state[y] = (u8)sx;
-	state[x] = (u8)sy;
-	return state[(sx + sy) & 0xff];
-}
-
-static void arcfour_encrypt(struct arc4context *parc4ctx, u8 *dest, u8 *src, u32 len)
-{
-	u32	i;
-
-	for (i = 0; i < len; i++)
-		dest[i] = src[i] ^ (unsigned char)arcfour_byte(parc4ctx);
-}
-
 static int bcrc32initialized;
 static u32 crc32_table[256];
 
@@ -564,7 +506,7 @@ u32	rtw_tkip_encrypt(struct adapter *padapter, struct xmit_frame *pxmitframe)
 	u8   ttkey[16];
 	u8	crc[4];
 	u8   hw_hdr_offset = 0;
-	struct arc4context mycontext;
+	struct arc4_ctx mycontext;
 	int			curfragnum, length;
 
 	u8	*pframe, *payload, *iv, *prwskey;
@@ -614,15 +556,15 @@ u32	rtw_tkip_encrypt(struct adapter *padapter, struct xmit_frame *pxmitframe)
 						 pattrib->iv_len, pattrib->icv_len));
 					*((__le32 *)crc) = getcrc32(payload, length);/* modified by Amy*/
 
-					arcfour_init(&mycontext, rc4key, 16);
-					arcfour_encrypt(&mycontext, payload, payload, length);
-					arcfour_encrypt(&mycontext, payload + length, crc, 4);
+					arc4_setkey(&mycontext, rc4key, 16);
+					arc4_crypt(&mycontext, payload, payload, length);
+					arc4_crypt(&mycontext, payload + length, crc, 4);
 				} else {
 					length = pxmitpriv->frag_len - pattrib->hdrlen - pattrib->iv_len - pattrib->icv_len;
 					*((__le32 *)crc) = getcrc32(payload, length);/* modified by Amy*/
-					arcfour_init(&mycontext, rc4key, 16);
-					arcfour_encrypt(&mycontext, payload, payload, length);
-					arcfour_encrypt(&mycontext, payload + length, crc, 4);
+					arc4_setkey(&mycontext, rc4key, 16);
+					arc4_crypt(&mycontext, payload, payload, length);
+					arc4_crypt(&mycontext, payload + length, crc, 4);
 
 					pframe += pxmitpriv->frag_len;
 					pframe = (u8 *)round_up((size_t)(pframe), 4);
@@ -644,7 +586,7 @@ u32 rtw_tkip_decrypt(struct adapter *padapter, struct recv_frame *precvframe)
 	u8   rc4key[16];
 	u8   ttkey[16];
 	u8	crc[4];
-	struct arc4context mycontext;
+	struct arc4_ctx mycontext;
 	int			length;
 	u8	*pframe, *payload, *iv, *prwskey;
 	union pn48 dot11txpn;
@@ -685,8 +627,8 @@ u32 rtw_tkip_decrypt(struct adapter *padapter, struct recv_frame *precvframe)
 
 			/* 4 decrypt payload include icv */
 
-			arcfour_init(&mycontext, rc4key, 16);
-			arcfour_encrypt(&mycontext, payload, payload, length);
+			arc4_setkey(&mycontext, rc4key, 16);
+			arc4_crypt(&mycontext, payload, payload, length);
 
 			*((__le32 *)crc) = getcrc32(payload, length - 4);
 
-- 
2.27.0

