now uses cbc to sent bigger messages

arduino-rx/arduino-rx.ino

@@ -10,6 +10,12 @@
 #include <RadioHead.h>
 #include <RH_ASK.h>
 #include <SPI.h> // Not actualy used but needed to compile
+#include <string.h>
+
+#define BLOCK_SIZE 16
+#define NUM_BLOCKS 4
+
+aes_context ctx; // context for the cbc crypto stuff
 
 RH_ASK driver;
 
@@ -24,6 +30,7 @@ EccPoint remotePubkey = {
     {0x90, 0x6F, 0xFC, 0xC8, 0x07, 0xA8, 0x93, 0x9C, 0x3B, 0xDC, 0xAF, 0xF1, 0x8D, 0xA9, 0x96, 0xF8, 0xC2, 0x3B, 0x85, 0x3E, 0x5C, 0x65, 0xDE, 0x32},
     {0xE1, 0xB1, 0x28, 0x7F, 0xD3, 0xB0, 0x94, 0x24, 0x69, 0x95, 0xDE, 0x76, 0x40, 0x15, 0x6E, 0xAE, 0x74, 0xE9, 0x56, 0x94, 0xA7, 0xE4, 0x63, 0xEF}};
 
+
 void p(char *fmt, ... ){
     char tmp[128]; // resulting string limited to 128 chars
     va_list args;
@@ -41,21 +48,36 @@ void dump(char *text, uint8_t *d) {
     Serial.print("\n");
 }
 
-char* encryptAES(uint8_t* p_secret, char* p_data)
+uint8_t* generateIV()
 {
-    Serial.print("\n");
-    Serial.println("encoding data...");
+    uint8_t buffer[BLOCK_SIZE];
+    Serial.println("generating IV...");
+    for (int i=0 ; i<BLOCK_SIZE ; i++){
+      buffer[i] = random(64);
+    }
+    for (int i = 0; i < 17; i++){
+     Serial.print(buffer[i]);
+    }
+    Serial.println("");
+    return buffer;
+}
+
+char* encryptAES(uint8_t* p_secret, char* p_data, const aes_context ctx)
+{
+    Serial.print("data:");
     Serial.println(p_data);
-    aes128_enc_single(p_secret, p_data);
+    Serial.print("encrypting data...");
+    aes128_cbc_enc_continue(ctx, p_data, BLOCK_SIZE*NUM_BLOCKS); 
+    aes128_cbc_enc_finish(ctx);
     Serial.println("done");
     return p_data;
 }
 
-char* decryptAES(uint8_t* p_secret, char* p_data)
+char* decryptAES(uint8_t* p_secret, char* p_data, const aes_context ctx)
 {
-    Serial.print("\n");                                                  
-    Serial.println("decoding data...");                                                                                                                                               
-    aes128_dec_single(p_secret, p_data);
+    Serial.print("decrypting data...");                                                                                                                                               
+    aes128_cbc_dec_continue(ctx, p_data, BLOCK_SIZE*NUM_BLOCKS);
+    aes128_cbc_dec_finish(ctx);
     Serial.println("done");
     return p_data;
 }
@@ -77,26 +99,31 @@ void setup()
     Serial.println("hoi");
     if (!driver.init())
          Serial.println("init failed");
+    randomSeed(analogRead(0));
 }
 
 void loop()
 {
     // Crypto // 
-    uint8_t sharedSecret =  calcSharedSecret(&remotePubkey, privkey);
+    char* data = "Hallo dit is een testbericht jwz";
 
-    char data[] = "0123456789012345";
-    char* encodedData;
-    char* decodedData;
+    uint8_t sharedSecret =  calcSharedSecret(&remotePubkey, privkey);
+    char* encryptedData;
+    char* decryptedData;
 
-    encodedData = encryptAES(&sharedSecret, data);
-    Serial.print("encoded data:");
-    Serial.println(encodedData);
+//    uint8_t* iv = generateIV();   
+    uint8_t iv[16] = {4,9,4,9,4,9,4,9,4,9,4,9,4,9,4,9};
+    ctx = aes128_cbc_enc_start(&sharedSecret, iv);
+    encryptedData = encryptAES(&sharedSecret, data, ctx);
 
-    decodedData = decryptAES(&sharedSecret, encodedData);
-    Serial.print("decoded data:");
-    Serial.println(decodedData);
+    ctx = aes128_cbc_enc_start(&sharedSecret, iv);
+    decryptedData = decryptAES(&sharedSecret, encryptedData, ctx);
+    Serial.print("decrypted data:");
+    Serial.println(decryptedData);
+    Serial.println ("");
 
     // Radio //
+/*
     uint8_t buf[RH_ASK_MAX_MESSAGE_LEN];
     uint8_t buflen = sizeof(buf);
    
@@ -107,4 +134,5 @@ void loop()
 	// Message with a good checksum received, dump it.
 	driver.printBuffer("Got encrypted:", buf, buflen);
     }
+*/
 }