AES128 encryption on Arduino - c++

Question

I am trying to use an arduino to encrypt data as AES128 and then decrypt it. I am also experimenting with AES192 and AES256 but first I'd like to get it to work with AES128. I am using the Cyptography Library and I am struggling to figure out what is happening here. In the code below one may observe that a testVector has a name to identify it, a unique key, plain text, and cipher text. When I tried modifying the ".plaintext" in the array it causes the encryption and thus decryption to fail. My goal is to encrypt "My Message" and then decrypt it afterwords.
Please see my code below:
#include <Crypto.h>
#include <AES.h>
#include <string.h>
struct TestVector
{
const char *name;
byte key[32];
byte plaintext[16];
byte ciphertext[16];
};
// Define the ECB test vectors from the FIPS specification.
static TestVector const testVectorAES128 = {
.name = "AES-128-ECB",
.key = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F},
.plaintext = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF},
.ciphertext = {0x69, 0xC4, 0xE0, 0xD8, 0x6A, 0x7B, 0x04, 0x30,
0xD8, 0xCD, 0xB7, 0x80, 0x70, 0xB4, 0xC5, 0x5A}
};
static TestVector const testVectorAES192 = {
.name = "AES-192-ECB",
.key = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17},
.plaintext = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF},
.ciphertext = {0xDD, 0xA9, 0x7C, 0xA4, 0x86, 0x4C, 0xDF, 0xE0,
0x6E, 0xAF, 0x70, 0xA0, 0xEC, 0x0D, 0x71, 0x91}
};
static TestVector const testVectorAES256 = {
.name = "AES-256-ECB",
.key = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F},
.plaintext = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF},
.ciphertext = {0x8E, 0xA2, 0xB7, 0xCA, 0x51, 0x67, 0x45, 0xBF,
0xEA, 0xFC, 0x49, 0x90, 0x4B, 0x49, 0x60, 0x89}
};
AES128 aes128;
AES192 aes192;
AES256 aes256;
byte buffer[16];
void testCipher(BlockCipher *cipher, const struct TestVector *test)
{
crypto_feed_watchdog();
Serial.print(test->name);
Serial.print(" Encryption ... ");
cipher->setKey(test->key, cipher->keySize());
cipher->encryptBlock(buffer, test->plaintext);
if (memcmp(buffer, test->ciphertext, 16) == 0){
Serial.println("Passed");
String myString = String((char*)buffer);
Serial.println(myString);
}
else
Serial.println("Failed");
Serial.print(test->name);
Serial.print(" Decryption ... ");
cipher->decryptBlock(buffer, test->ciphertext);
if (memcmp(buffer, test->plaintext, 16) == 0){
Serial.println("Passed");
String myString2 = String((char*)buffer);
Serial.println(myString2);
}
else
Serial.println("Failed");
}
void perfCipher(BlockCipher *cipher, const struct TestVector *test)
{
unsigned long start;
unsigned long elapsed;
int count;
crypto_feed_watchdog();
Serial.print(test->name);
Serial.print(" Set Key ... ");
start = micros();
for (count = 0; count < 10000; ++count) {
cipher->setKey(test->key, cipher->keySize());
}
elapsed = micros() - start;
Serial.print(elapsed / 10000.0);
Serial.print("us per operation, ");
Serial.print((10000.0 * 1000000.0) / elapsed);
Serial.println(" per second");
Serial.print(test->name);
Serial.print(" Encrypt ... ");
start = micros();
for (count = 0; count < 5000; ++count) {
cipher->encryptBlock(buffer, buffer);
}
elapsed = micros() - start;
Serial.print(elapsed / (5000.0 * 16.0));
Serial.print("us per byte, ");
Serial.print((16.0 * 5000.0 * 1000000.0) / elapsed);
Serial.println(" bytes per second");
Serial.print(test->name);
Serial.print(" Decrypt ... ");
start = micros();
for (count = 0; count < 5000; ++count) {
cipher->decryptBlock(buffer, buffer);
}
elapsed = micros() - start;
Serial.print(elapsed / (5000.0 * 16.0));
Serial.print("us per byte, ");
Serial.print((16.0 * 5000.0 * 1000000.0) / elapsed);
Serial.println(" bytes per second");
Serial.println();
}
void setup()
{
Serial.begin(9600);
Serial.println();
Serial.println("State Sizes:");
Serial.print("AES128 ... ");
Serial.println(sizeof(AES128));
Serial.print("AES192 ... ");
Serial.println(sizeof(AES192));
Serial.print("AES256 ... ");
Serial.println(sizeof(AES256));
Serial.println();
Serial.println("Test Vectors:");
testCipher(&aes128, &testVectorAES128);
testCipher(&aes192, &testVectorAES192);
testCipher(&aes256, &testVectorAES256);
Serial.println();
Serial.println("Performance Tests:");
perfCipher(&aes128, &testVectorAES128);
perfCipher(&aes192, &testVectorAES192);
perfCipher(&aes256, &testVectorAES256);
}
void loop()
{
}
Here is some information on the library:
https://rweather.github.io/arduinolibs/classBlockCipher.html#ac3ba2450222aa1ea804ae4881ab6440c