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.jail...@wanadoo.fr>
---
 drivers/staging/rtl8712/rtl871x_security.c | 118 +++++----------------
 1 file changed, 29 insertions(+), 89 deletions(-)

diff --git a/drivers/staging/rtl8712/rtl871x_security.c 
b/drivers/staging/rtl8712/rtl871x_security.c
index 1c7df65db3c9..b546e2f19620 100644
--- a/drivers/staging/rtl8712/rtl871x_security.c
+++ b/drivers/staging/rtl8712/rtl871x_security.c
@@ -16,6 +16,7 @@
 
 #define  _RTL871X_SECURITY_C_
 
+#include <crypto/arc4.h>
 #include <linux/compiler.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
@@ -38,66 +39,6 @@
 
 /* =====WEP related===== */
 
-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 sint bcrc32initialized;
 static u32 crc32_table[256];
 
@@ -151,7 +92,7 @@ static u32 getcrc32(u8 *buf, u32 len)
 void r8712_wep_encrypt(struct _adapter *padapter, u8 *pxmitframe)
 {      /* exclude ICV */
        unsigned char   crc[4];
-       struct arc4context  mycontext;
+       struct arc4_ctx  mycontext;
        u32 curfragnum, length, keylength, pki;
        u8 *pframe, *payload, *iv;    /*,*wepkey*/
        u8 wepkey[16];
@@ -182,22 +123,22 @@ void r8712_wep_encrypt(struct _adapter *padapter, u8 
*pxmitframe)
                                        pattrib->icv_len;
                                *((__le32 *)crc) = cpu_to_le32(getcrc32(
                                                payload, length));
-                               arcfour_init(&mycontext, wepkey, 3 + keylength);
-                               arcfour_encrypt(&mycontext, payload, payload,
-                                               length);
-                               arcfour_encrypt(&mycontext, payload + length,
-                                               crc, 4);
+                               arc4_setkey(&mycontext, wepkey, 3 + keylength);
+                               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) = cpu_to_le32(getcrc32(
                                                payload, length));
-                               arcfour_init(&mycontext, wepkey, 3 + keylength);
-                               arcfour_encrypt(&mycontext, payload, payload,
-                                               length);
-                               arcfour_encrypt(&mycontext, payload + length,
-                                               crc, 4);
+                               arc4_setkey(&mycontext, wepkey, 3 + keylength);
+                               arc4_crypt(&mycontext, payload, payload,
+                                          length);
+                               arc4_crypt(&mycontext, payload + length,
+                                          crc, 4);
                                pframe += pxmitpriv->frag_len;
                                pframe = (u8 *)RND4((addr_t)(pframe));
                        }
@@ -209,7 +150,7 @@ void r8712_wep_decrypt(struct _adapter  *padapter, u8 
*precvframe)
 {
        /* exclude ICV */
        u8 crc[4];
-       struct arc4context  mycontext;
+       struct arc4_ctx mycontext;
        u32 length, keylength;
        u8 *pframe, *payload, *iv, wepkey[16];
        u8  keyindex;
@@ -233,8 +174,8 @@ void r8712_wep_decrypt(struct _adapter  *padapter, u8 
*precvframe)
                           u.hdr.len - prxattrib->hdrlen - prxattrib->iv_len;
                payload = pframe + prxattrib->iv_len + prxattrib->hdrlen;
                /* decrypt payload include icv */
-               arcfour_init(&mycontext, wepkey, 3 + keylength);
-               arcfour_encrypt(&mycontext, payload, payload,  length);
+               arc4_setkey(&mycontext, wepkey, 3 + keylength);
+               arc4_crypt(&mycontext, payload, payload, length);
                /* calculate icv and compare the icv */
                *((__le32 *)crc) = cpu_to_le32(getcrc32(payload, length - 4));
        }
@@ -563,7 +504,7 @@ u32 r8712_tkip_encrypt(struct _adapter *padapter, u8 
*pxmitframe)
        u8 rc4key[16];
        u8 ttkey[16];
        u8 crc[4];
-       struct arc4context mycontext;
+       struct arc4_ctx mycontext;
        u32 curfragnum, length;
 
        u8 *pframe, *payload, *iv, *prwskey;
@@ -606,11 +547,11 @@ u32 r8712_tkip_encrypt(struct _adapter *padapter, u8 
*pxmitframe)
                                             pattrib->icv_len;
                                        *((__le32 *)crc) = cpu_to_le32(
                                                getcrc32(payload, length));
-                                       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 -
@@ -618,12 +559,11 @@ u32 r8712_tkip_encrypt(struct _adapter *padapter, u8 
*pxmitframe)
                                                 pattrib->icv_len;
                                        *((__le32 *)crc) = cpu_to_le32(getcrc32(
                                                        payload, length));
-                                       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 *)RND4((addr_t)(pframe));
                                }
@@ -643,7 +583,7 @@ void r8712_tkip_decrypt(struct _adapter *padapter, u8 
*precvframe)
        u8 rc4key[16];
        u8 ttkey[16];
        u8 crc[4];
-       struct arc4context mycontext;
+       struct arc4_ctx mycontext;
        u32 length;
        u8 *pframe, *payload, *iv, *prwskey, idx = 0;
        union pn48 txpn;
@@ -682,8 +622,8 @@ void r8712_tkip_decrypt(struct _adapter *padapter, u8 
*precvframe)
                        phase2(&rc4key[0], prwskey, (unsigned short *)
                               &ttkey[0], pnl);
                        /* 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) = cpu_to_le32(getcrc32(payload,
                                        length - 4));
                }
-- 
2.27.0

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