Diff: aes.cpp

Revision:

8:5879e83f632a

Parent:

1:d3b7bde3995c

--- a/aes.cpp	Thu Feb 25 21:28:23 2016 +0000
+++ b/aes.cpp	Mon Apr 02 12:04:59 2018 +0000
@@ -7,11 +7,23 @@
  *
  * Contributors:
  *    IBM Zurich Research Lab - initial API, implementation and documentation
- *******************************************************************************/
+ *
+ * /////////////////////////////////////////////////////////////////////////////
+ *
+ * Used by Giorgos Tsapparellas for Internet of Things (IoT) smart monitoring
+ * device for agriculture using LoRaWAN technology.
+ *
+ * Date of issued copy: 25 January 2018
+ *
+ * Modifications: 
+ * - No external modifications of the existing "AS IT IS" software.
+ * - Added some external comments for meeting good principles of 
+ *   source code re-usability.   
+ ******************************************************************************/
 
 #include "oslmic.h"
 
-#define AES_MICSUB 0x30 // internal use only
+#define AES_MICSUB 0x30 // Internal use only.
 
 static const u4_t AES_RCON[10] = { 
     0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000, 
@@ -199,12 +211,18 @@
                                    a ^= (AES_S[u1(r2>> 8)]<< 8); \
                                    a ^=  AES_S[u1(r3)    ]
 
-// global area for passing parameters (aux, key) and for storing round keys
+// Global area for passing parameters (aux, key) and for storing round keys.
 u4_t AESAUX[16/sizeof(u4_t)];
 u4_t AESKEY[11*16/sizeof(u4_t)];
 
-// generate 1+10 roundkeys for encryption with 128-bit key
-// read 128-bit key from AESKEY in MSBF, generate roundkey words in place
+/* 
+* aesroundkeys function of type static void.
+* Generate 1+10 roundkeys for encryption with 128-bit key.
+* Read 128-bit key from AESKEY in MSBF, generate roundkey words in place.
+*
+* Input parameters: None
+*
+*/ 
 static void aesroundkeys () {
     int i;
     u4_t b;
@@ -225,8 +243,17 @@
         }
         AESKEY[i] = b ^= AESKEY[i-4];
     }
-}
+} // end of aesroundkeys function.
 
+/* 
+* os_aes function of type unsigned integer.
+*
+* Input parameters: unsigned int mode
+*                   unsigned int buf
+*                   unsigned int short len
+*
+* Return: AESAUX[0]
+*/ 
 u4_t os_aes (u1_t mode, xref2u1_t buf, u2_t len) {
         
         aesroundkeys();
@@ -363,5 +390,5 @@
             mode |= AES_MICNOAUX;
         }
         return AESAUX[0];
-}
+} // end of os_aes function.