diff --git a/lib/src/common/liblte_security.cc b/lib/src/common/liblte_security.cc
index d8f76bf2c..7045ff2ac 100644
--- a/lib/src/common/liblte_security.cc
+++ b/lib/src/common/liblte_security.cc
@@ -1099,7 +1099,7 @@ LIBLTE_ERROR_ENUM liblte_security_decryption_eea2(uint8 *key,
     Document Reference: 35.206 v10.0.0 Annex 3
 *********************************************************************/
 LIBLTE_ERROR_ENUM liblte_security_milenage_f1(uint8 *k,
-                                              uint8 *op,
+                                              uint8 *op_c,
                                               uint8 *rand,
                                               uint8 *sqn,
                                               uint8 *amf,
@@ -1108,13 +1108,13 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f1(uint8 *k,
     LIBLTE_ERROR_ENUM err = LIBLTE_ERROR_INVALID_INPUTS;
     ROUND_KEY_STRUCT  round_keys;
     uint32            i;
-    uint8             op_c[16];
     uint8             temp[16];
     uint8             in1[16];
     uint8             out1[16];
     uint8             rijndael_input[16];
 
     if(k     != NULL &&
+       op_c  != NULL &&
        rand  != NULL &&
        sqn   != NULL &&
        amf   != NULL &&
@@ -1123,14 +1123,6 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f1(uint8 *k,
         // Initialize the round keys
         rijndael_key_schedule(k, &round_keys);
 
-        // Compute OPc
-        for(i=0;i<16;i++)
-        {
-            op_c[i] = op[i];
-        }
-
-        //compute_OPc(&round_keys, op, op_c);
-
         // Compute temp
         for(i=0; i<16; i++)
         {
@@ -1188,7 +1180,7 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f1(uint8 *k,
     Document Reference: 35.206 v10.0.0 Annex 3
 *********************************************************************/
 LIBLTE_ERROR_ENUM liblte_security_milenage_f1_star(uint8 *k,
-                                                   uint8 *op,
+                                                   uint8 *op_c,
                                                    uint8 *rand,
                                                    uint8 *sqn,
                                                    uint8 *amf,
@@ -1197,13 +1189,13 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f1_star(uint8 *k,
     LIBLTE_ERROR_ENUM err = LIBLTE_ERROR_INVALID_INPUTS;
     ROUND_KEY_STRUCT  round_keys;
     uint32            i;
-    uint8             op_c[16];
     uint8             temp[16];
     uint8             in1[16];
     uint8             out1[16];
     uint8             rijndael_input[16];
 
     if(k     != NULL &&
+       op_c  != NULL &&
        rand  != NULL &&
        sqn   != NULL &&
        amf   != NULL &&
@@ -1212,14 +1204,6 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f1_star(uint8 *k,
         // Initialize the round keys
         rijndael_key_schedule(k, &round_keys);
 
-        for(i=0;i<16;i++)
-        {
-          op_c[i] = op[i];
-        }
-
-        // Compute OPc
-        //compute_OPc(&round_keys, op, op_c);
-
         // Compute temp
         for(i=0; i<16; i++)
         {
@@ -1277,7 +1261,7 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f1_star(uint8 *k,
     Document Reference: 35.206 v10.0.0 Annex 3
 *********************************************************************/
 LIBLTE_ERROR_ENUM liblte_security_milenage_f2345(uint8 *k,
-                                                 uint8 *op,
+                                                 uint8 *op_c,
                                                  uint8 *rand,
                                                  uint8 *res,
                                                  uint8 *ck,
@@ -1287,12 +1271,12 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f2345(uint8 *k,
     LIBLTE_ERROR_ENUM err = LIBLTE_ERROR_INVALID_INPUTS;
     ROUND_KEY_STRUCT  round_keys;
     uint32            i;
-    uint8             op_c[16];
     uint8             temp[16];
     uint8             out[16];
     uint8             rijndael_input[16];
 
     if(k    != NULL &&
+       op_c != NULL &&
        rand != NULL &&
        res  != NULL &&
        ck   != NULL &&
@@ -1302,12 +1286,6 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f2345(uint8 *k,
         // Initialize the round keys
         rijndael_key_schedule(k, &round_keys);
 
-        // Compute OPc
-        //compute_OPc(&round_keys, op, op_c);
-        for(i=0;i<16;i++)
-        {
-          op_c[i] = op[i];
-        }
         // Compute temp
         for(i=0; i<16; i++)
         {
@@ -1391,7 +1369,7 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f2345(uint8 *k,
     Document Reference: 35.206 v10.0.0 Annex 3
 *********************************************************************/
 LIBLTE_ERROR_ENUM liblte_security_milenage_f5_star(uint8 *k,
-                                                   uint8 *op,
+                                                   uint8 *op_c,
                                                    uint8 *rand,
                                                    uint8 *ak)
 {
@@ -1404,19 +1382,13 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f5_star(uint8 *k,
     uint8             rijndael_input[16];
 
     if(k    != NULL &&
+       op_c != NULL &&
        rand != NULL &&
        ak   != NULL)
     {
         // Initialize the round keys
         rijndael_key_schedule(k, &round_keys);
 
-        // Compute OPc
-        //compute_OPc(&round_keys, op, op_c);
-        for(i=0;i<16;i++)
-        {
-            op_c[i] = op[i];
-        }
-
         // Compute temp
         for(i=0; i<16; i++)
         {
@@ -1441,17 +1413,11 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f5_star(uint8 *k,
         {
             ak[i] = out[i];
         }
-
         err = LIBLTE_SUCCESS;
     }
-
     return(err);
 }
 
-/*******************************************************************************
-                              LOCAL FUNCTIONS
-*******************************************************************************/
-
 /*********************************************************************
     Name: compute_OPc
 
@@ -1459,19 +1425,25 @@ LIBLTE_ERROR_ENUM liblte_security_milenage_f5_star(uint8 *k,
 
     Document Reference: 35.206 v10.0.0 Annex 3
 *********************************************************************/
-void compute_OPc(ROUND_KEY_STRUCT *rk,
+void compute_OPc(uint8            *k,
                  uint8            *op,
                  uint8            *op_c)
 {
-    uint32 i;
-
-    rijndael_encrypt(op, rk, op_c);
-    for(i=0; i<16; i++)
-    {
-        op_c[i] ^= op[i];
-    }
+  uint32 i;
+  ROUND_KEY_STRUCT round_keys;
+  rijndael_key_schedule(k, &round_keys);
+  rijndael_encrypt(op, round_keys, op_c);
+  for(i=0; i<16; i++)
+  {
+    op_c[i] ^= op[i];
+  }
 }
 
+/*******************************************************************************
+                              LOCAL FUNCTIONS
+*******************************************************************************/
+
+
 /*********************************************************************
     Name: rijndael_key_schedule