Diff: main.cpp

Revision:

0:20df98087dc9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri May 05 20:14:32 2017 +0000
@@ -0,0 +1,109 @@
+#include "mbed.h"
+
+//------------------------------------
+// Hyperterminal configuration
+// 9600 bauds, 8-bit data, no parity
+//------------------------------------
+
+#include "mbedtls/aes.h"
+
+#define IV_SIZE     16
+#define INPUT_SIZE  256
+
+Serial pc(USBTX, USBRX);
+
+// Indicator LED
+DigitalOut myled(LED1);
+
+// This function initializes the initilization vector to the original one.
+void init_ivs(unsigned char iv_orig[], unsigned char iv1[], unsigned char iv2[]);
+
+
+int main()
+{
+    int i=0;
+    
+    // We create two AES contexts
+    mbedtls_aes_context aes;
+    mbedtls_aes_context aes2;
+
+    // Our KEY , should be shared only with the receiver and has to be as random as possible.
+    // Here we use this simple example for ease and simplicity
+    unsigned char key[32] = "1234567812345678123456781234567" ; 
+    key[31] = '8';   // we replace the 32th (index 31) which contains '/0' with the '8' char.
+
+    // This is the Init Vector generated with the random KEY from http://aes.online-domain-tools.com/
+    unsigned char orig_iv[] = {0x8d, 0xf8, 0x4d, 0xed, 0x5f, 0xbd, 0x51, 0x57, 0x5c, 0x55, 0x17, 0xb0, 0x66, 0xee, 0xb1,  0x2b}; // e053a4a22fd6bfaf43fd5e8b5"; {0xb2, 0x4b, 0xf2, 0xf7, 0x7a, 0xc5, 0xec, 0x0c, 0x5e, 0x1f, 0x4d, 0xc1, 0xae, 0x46, 0x5e, 0x75};
+    unsigned char iv1[IV_SIZE] = {0};
+    unsigned char iv2[IV_SIZE] =  {0};
+
+    // This is the text that we want to encrypt and send
+    unsigned char my_txt[] = "My name is Ritesh Reddy Sadula";
+
+    unsigned char input[INPUT_SIZE] = {0};
+    
+    for(int m=0; m<strlen((const char*)my_txt); m++)
+    {
+        input[m] = *(my_txt+m);
+    }
+       
+
+    // Output of encryption
+    unsigned char output[INPUT_SIZE] = {0};
+    // Output of decryption
+    unsigned char output2[INPUT_SIZE] = {0};
+ 
+    int ret =0;
+    
+    // To be a valid length, it has to be a multiple of 16, so we take the muliple of 16 that is nearly bigger than the actual size
+    // Or the 
+    int TXT_VALID_LENGTH = ((strlen((const char*)my_txt)%16 == 0)  ?  strlen((const char*)my_txt) :  (strlen((const char*)my_txt)/16 + 1)*16);
+    while(1){
+        init_ivs(orig_iv , iv1, iv2);
+        
+        
+        mbedtls_aes_setkey_enc( &aes, key, 256);
+        ret = mbedtls_aes_crypt_cbc( &aes, MBEDTLS_AES_ENCRYPT, TXT_VALID_LENGTH, iv1, input, output );
+        pc.printf("%d  -  Ret: %d  - strlen(input)=%d -  ENCRYPTED output  %s\n", i, ret , TXT_VALID_LENGTH, output);
+        
+        // We can use 64encoding to send data and to avoid encoding problems
+        // In our case we use haxadecimal representation of the characters so no need.  
+       // mbedtls_base64_encode(encoded64, 200, &out_len, (const unsigned char *)output, strlen((const char*)output) );
+       // printf("%d  64ENCODED ENCRYPTED  output  %s\n", i, encoded64);
+       
+        pc.printf("%d  HEX ENCRYPTED output\n", i);
+        for(int j=0; j<TXT_VALID_LENGTH; j++)
+        {
+            pc.printf("%02x ", output[j]);
+        }
+        pc.printf("\n");
+        
+        // We decrypt the OUTPUT1 and we get the same input string
+    
+        mbedtls_aes_setkey_dec( &aes2, key, 256);
+        ret = mbedtls_aes_crypt_cbc(&aes2, MBEDTLS_AES_DECRYPT, TXT_VALID_LENGTH, iv2, output, output2 );
+        pc.printf("%d  -  Ret: %d  -  DECRYPTED output  %s\n\n", i , ret,  output2);
+        
+        // Showing the decrypted result in HEX
+        pc.printf("%d  HEX DECRYPTED output\n", i, output2);
+        for(int j=0; j<TXT_VALID_LENGTH; j++)
+        {
+            pc.printf("%02x ", output2[j]);
+        }
+        pc.printf("\n\n\n");
+    
+        i++;
+        // Wait 2 seconds and re-do it.
+        wait(2);
+    }
+    
+}
+
+void init_ivs(unsigned char iv_orig[], unsigned char iv1[], unsigned char iv2[])
+{
+    for(int i=0; i<IV_SIZE; i++){
+    
+         iv2[i] = iv1[i] = iv_orig[i];
+        
+    }
+}
\ No newline at end of file