diff --git a/OpenCL/inc_cipher_aes-gcm.cl b/OpenCL/inc_cipher_aes-gcm.cl
index d08bc40f6..efc05bd09 100644
--- a/OpenCL/inc_cipher_aes-gcm.cl
+++ b/OpenCL/inc_cipher_aes-gcm.cl
@@ -10,6 +10,7 @@
 #include "inc_cipher_aes.h"
 #include "inc_cipher_aes-gcm.h"
 
+#ifndef AES_GCM_ALT1
 DECLSPEC void AES_GCM_shift_right_block(uchar *block)
 {
   u32 val;
@@ -36,6 +37,7 @@ DECLSPEC void AES_GCM_shift_right_block(uchar *block)
   val >>= 1;
   p[0].x = hc_swap32_S (val);
 }
+#endif // AES_GCM_ALT1
 
 DECLSPEC void AES_GCM_inc32 (u32 *block)
 {
@@ -52,14 +54,21 @@ DECLSPEC void AES_GCM_xor_block (u32 *dst, const u32 *src)
 
 DECLSPEC void AES_GCM_gf_mult (const uchar16 *x, const uchar16 *y, uchar16 *z)
 {
-  u32 i, j, k;
+  u32 i, j;
 
   z[0] = 0;
+
   uchar16 v = y[0].s32107654ba98fedc;
 
   u8 x_char[16] = { x[0].s3, x[0].s2, x[0].s1, x[0].s0, x[0].s7, x[0].s6, x[0].s5, x[0].s4, x[0].sb, x[0].sa, x[0].s9, x[0].s8, x[0].sf, x[0].se, x[0].sd, x[0].sc };
 
+  #ifndef AES_GCM_ALT1
   u8 *v_char = (u8 *) &v;
+  #endif
+
+  u32 *i_char = (u32 *) &v;
+
+  u8 t = 0;
 
   for (i = 0; i < 16; i++)
   {
@@ -70,15 +79,35 @@ DECLSPEC void AES_GCM_gf_mult (const uchar16 *x, const uchar16 *y, uchar16 *z)
         z[0] ^= v;
       }
 
-      if (v.sf & 0x01)
+      t = v.sf & 0x01;
+
+      #ifndef AES_GCM_ALT1
+
+      AES_GCM_shift_right_block(v_char);
+
+      #else
+
+      i_char[0] = hc_swap32_S (i_char[0]);
+      i_char[1] = hc_swap32_S (i_char[1]);
+      i_char[2] = hc_swap32_S (i_char[2]);
+      i_char[3] = hc_swap32_S (i_char[3]);
+
+      i_char[3] = (i_char[3] >> 1) | (i_char[2] << 31);
+      i_char[2] = (i_char[2] >> 1) | (i_char[1] << 31);
+      i_char[1] = (i_char[1] >> 1) | (i_char[0] << 31);
+      i_char[0] >>= 1;
+
+      i_char[0] = hc_swap32_S (i_char[0]);
+      i_char[1] = hc_swap32_S (i_char[1]);
+      i_char[2] = hc_swap32_S (i_char[2]);
+      i_char[3] = hc_swap32_S (i_char[3]);
+
+      #endif // AES_GCM_ALT1
+
+      if (t)
       {
-        AES_GCM_shift_right_block(v_char);
         v.s0 ^= 0xe1;
       }
-      else
-      {
-        AES_GCM_shift_right_block(v_char);
-      }
     }
   }
 }
@@ -87,7 +116,7 @@ DECLSPEC void AES_GCM_ghash (const u32 *subkey, const u32 *in, u32 in_len, u32 *
 {
   u32 m = in_len / 16;
 
-  u32 *xpos = in;
+  const u32 *xpos = in;
 
   u32 tmp[4] = { 0 };
 
@@ -97,7 +126,7 @@ DECLSPEC void AES_GCM_ghash (const u32 *subkey, const u32 *in, u32 in_len, u32 *
 
     xpos += 4;
 
-    AES_GCM_gf_mult (out, subkey, tmp);
+    AES_GCM_gf_mult ((uchar16 *) out, (uchar16 *) subkey, (uchar16 *) tmp);
 
     tmp[0] = hc_swap32_S (tmp[0]);
     tmp[1] = hc_swap32_S (tmp[1]);
@@ -126,7 +155,7 @@ DECLSPEC void AES_GCM_ghash (const u32 *subkey, const u32 *in, u32 in_len, u32 *
 
     AES_GCM_xor_block (out, tmp);
 
-    AES_GCM_gf_mult (out, subkey, tmp);
+    AES_GCM_gf_mult ((uchar16 *) out, (uchar16 *) subkey, (uchar16 *) tmp);
 
     out[0] = tmp[0];
     out[1] = tmp[1];
diff --git a/OpenCL/inc_cipher_aes-gcm.h b/OpenCL/inc_cipher_aes-gcm.h
index 97049a702..33e43ed12 100644
--- a/OpenCL/inc_cipher_aes-gcm.h
+++ b/OpenCL/inc_cipher_aes-gcm.h
@@ -6,7 +6,10 @@
 #ifndef _INC_CIPHER_AES_GCM_H
 #define _INC_CIPHER_AES_GCM_H
 
+#ifndef AES_GCM_ALT1
 DECLSPEC void AES_GCM_shift_right_block(uchar *block);
+#endif
+
 DECLSPEC void AES_GCM_inc32 (u32 *block);
 DECLSPEC void AES_GCM_xor_block (u32 *dst, const u32 *src);
 DECLSPEC void AES_GCM_gf_mult (const uchar16 *x, const uchar16 *y, uchar16 *z);
diff --git a/OpenCL/m27000-optimized.cl b/OpenCL/m27000-optimized.cl
index f05d456ac..53cde203f 100644
--- a/OpenCL/m27000-optimized.cl
+++ b/OpenCL/m27000-optimized.cl
@@ -4,6 +4,7 @@
  */
 
 #define NEW_SIMD_CODE
+#define AES_GCM_ALT1
 
 #ifdef KERNEL_STATIC
 #include "inc_vendor.h"
@@ -281,15 +282,15 @@ KERNEL_FQ void m27000_comp (KERN_ATTR_TMPS_ESALT (pbkdf2_sha256_tmp_t, pbkdf2_sh
 
   if (gid >= gid_max) return;
 
-  const u64 lid = get_local_id (0);
-  const u64 lsz = get_local_size (0);
-
   /**
    * aes shared
    */
 
   #ifdef REAL_SHM
 
+  const u64 lid = get_local_id (0);
+  const u64 lsz = get_local_size (0);
+
   LOCAL_VK u32 s_te0[256];
   LOCAL_VK u32 s_te1[256];
   LOCAL_VK u32 s_te2[256];
@@ -332,9 +333,8 @@ KERNEL_FQ void m27000_comp (KERN_ATTR_TMPS_ESALT (pbkdf2_sha256_tmp_t, pbkdf2_sh
   ukey[6] = tmps[gid].out[6];
   ukey[7] = tmps[gid].out[7];
 
-  u32 key_len = 32 * 8;
-
   u32 key[60] = { 0 };
+
   u32 subKey[4] = { 0 };
 
   AES256_set_encrypt_key (key, ukey, s_te0, s_te1, s_te2, s_te3);
@@ -350,8 +350,6 @@ KERNEL_FQ void m27000_comp (KERN_ATTR_TMPS_ESALT (pbkdf2_sha256_tmp_t, pbkdf2_sh
     esalt_bufs[DIGESTS_OFFSET].iv_buf[3]
   };
 
-  const u32 iv_len = esalt_bufs[DIGESTS_OFFSET].iv_len;
-
   u32 J0[4] = {
     iv[0],
     iv[1],
@@ -389,7 +387,7 @@ KERNEL_FQ void m27000_comp (KERN_ATTR_TMPS_ESALT (pbkdf2_sha256_tmp_t, pbkdf2_sh
   S[2] ^= enc[2];
   S[3] ^= enc[3];
 
-  AES_GCM_gf_mult (S, subKey, t);
+  AES_GCM_gf_mult ((uchar16 *) S, (uchar16 *) subKey, (uchar16 *) t);
 
   t[0] = hc_swap32_S (t[0]);
   t[1] = hc_swap32_S (t[1]);
@@ -401,7 +399,7 @@ KERNEL_FQ void m27000_comp (KERN_ATTR_TMPS_ESALT (pbkdf2_sha256_tmp_t, pbkdf2_sh
   S[2] = t[2] ^ enc[6];
   S[3] = t[3] ^ enc[7];
 
-  AES_GCM_gf_mult (S, subKey, t);
+  AES_GCM_gf_mult ((uchar16 *) S, (uchar16 *) subKey, (uchar16 *) t);
 
   t[0] = hc_swap32_S (t[0]);
   t[1] = hc_swap32_S (t[1]);
@@ -413,7 +411,7 @@ KERNEL_FQ void m27000_comp (KERN_ATTR_TMPS_ESALT (pbkdf2_sha256_tmp_t, pbkdf2_sh
   S[2] = t[2] ^ enc[10];
   S[3] = t[3] ^ enc[11];
 
-  AES_GCM_gf_mult (S, subKey, t);
+  AES_GCM_gf_mult ((uchar16 *) S, (uchar16 *) subKey, (uchar16 *) t);
 
   t[0] = hc_swap32_S (t[0]);
   t[1] = hc_swap32_S (t[1]);
@@ -435,7 +433,7 @@ KERNEL_FQ void m27000_comp (KERN_ATTR_TMPS_ESALT (pbkdf2_sha256_tmp_t, pbkdf2_sh
   S[2] ^= t[2];
   S[3] ^= t[3];
 
-  AES_GCM_gf_mult (S, subKey, t);
+  AES_GCM_gf_mult ((uchar16 *) S, (uchar16 *) subKey, (uchar16 *) t);
 
   S[0] = hc_swap32_S (t[0]);
   S[1] = hc_swap32_S (t[1]);
@@ -452,7 +450,7 @@ KERNEL_FQ void m27000_comp (KERN_ATTR_TMPS_ESALT (pbkdf2_sha256_tmp_t, pbkdf2_sh
   S[2] ^= len_buf[2];
   S[3] ^= len_buf[3];
 
-  AES_GCM_gf_mult (S, subKey, t);
+  AES_GCM_gf_mult ((uchar16 *) S, (uchar16 *) subKey, (uchar16 *) t);
 
   S[0] = hc_swap32_S (t[0]);
   S[1] = hc_swap32_S (t[1]);
diff --git a/OpenCL/m27000-pure.cl b/OpenCL/m27000-pure.cl
index 23a377985..30151a0dc 100644
--- a/OpenCL/m27000-pure.cl
+++ b/OpenCL/m27000-pure.cl
@@ -4,6 +4,7 @@
  */
 
 #define NEW_SIMD_CODE
+#define AES_GCM_ALT1
 
 #ifdef KERNEL_STATIC
 #include "inc_vendor.h"
@@ -281,15 +282,15 @@ KERNEL_FQ void m27000_comp (KERN_ATTR_TMPS_ESALT (pbkdf2_sha256_tmp_t, pbkdf2_sh
 
   if (gid >= gid_max) return;
 
-  const u64 lid = get_local_id (0);
-  const u64 lsz = get_local_size (0);
-
   /**
    * aes shared
    */
 
   #ifdef REAL_SHM
 
+  const u64 lid = get_local_id (0);
+  const u64 lsz = get_local_size (0);
+
   LOCAL_VK u32 s_te0[256];
   LOCAL_VK u32 s_te1[256];
   LOCAL_VK u32 s_te2[256];
@@ -386,7 +387,7 @@ KERNEL_FQ void m27000_comp (KERN_ATTR_TMPS_ESALT (pbkdf2_sha256_tmp_t, pbkdf2_sh
   u32 S[4] = { 0 };
 
   u32 S_len   = 16;
-  u32 aad_buf = 0;
+  u32 aad_buf[4] = { 0 };
   u32 aad_len = 0;
 
   AES_GCM_GHASH (subKey, aad_buf, aad_len, enc, enc_len, S);