Here is the example sketch I'm using:
/*
* Copyright (C) 2015 Southern Storm Software, Pty Ltd.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
/*
This example runs tests on the CTR implementation to verify correct behaviour.
*/
#include <Crypto.h>
#include <AES.h>
#include <CTR.h>
#include <string.h>
#define MAX_PLAINTEXT_SIZE 36
#define MAX_CIPHERTEXT_SIZE 36
struct TestVector
{
const char *name;
byte key[16];
byte plaintext[MAX_PLAINTEXT_SIZE];
byte ciphertext[MAX_CIPHERTEXT_SIZE];
byte iv[16];
size_t size;
};
// Test vectors for AES-128 in CTR mode from RFC 3686.
static TestVector const testVectorAES128CTR1 = {
.name = "AES-128-CTR #1",
.key = {0xAE, 0x68, 0x52, 0xF8, 0x12, 0x10, 0x67, 0xCC,
0x4B, 0xF7, 0xA5, 0x76, 0x55, 0x77, 0xF3, 0x9E},
.plaintext = {0x53, 0x69, 0x6E, 0x67, 0x6C, 0x65, 0x20, 0x62,
0x6C, 0x6F, 0x63, 0x6B, 0x20, 0x6D, 0x73, 0x67},
.ciphertext = {0xE4, 0x09, 0x5D, 0x4F, 0xB7, 0xA7, 0xB3, 0x79,
0x2D, 0x61, 0x75, 0xA3, 0x26, 0x13, 0x11, 0xB8},
.iv = {0x00, 0x00, 0x00, 0x30, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01},
.size = 16
};
static TestVector const testVectorAES128CTR2 = {
.name = "AES-128-CTR #2",
.key = {0x7E, 0x24, 0x06, 0x78, 0x17, 0xFA, 0xE0, 0xD7,
0x43, 0xD6, 0xCE, 0x1F, 0x32, 0x53, 0x91, 0x63},
.plaintext = {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},
.ciphertext = {0x51, 0x04, 0xA1, 0x06, 0x16, 0x8A, 0x72, 0xD9,
0x79, 0x0D, 0x41, 0xEE, 0x8E, 0xDA, 0xD3, 0x88,
0xEB, 0x2E, 0x1E, 0xFC, 0x46, 0xDA, 0x57, 0xC8,
0xFC, 0xE6, 0x30, 0xDF, 0x91, 0x41, 0xBE, 0x28},
.iv = {0x00, 0x6C, 0xB6, 0xDB, 0xC0, 0x54, 0x3B, 0x59,
0xDA, 0x48, 0xD9, 0x0B, 0x00, 0x00, 0x00, 0x01},
.size = 32
};
static TestVector const testVectorAES128CTR3 = {
.name = "AES-128-CTR #3",
.key = {0x76, 0x91, 0xBE, 0x03, 0x5E, 0x50, 0x20, 0xA8,
0xAC, 0x6E, 0x61, 0x85, 0x29, 0xF9, 0xA0, 0xDC},
.plaintext = {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,
0x20, 0x21, 0x22, 0x23},
.ciphertext = {0xC1, 0xCF, 0x48, 0xA8, 0x9F, 0x2F, 0xFD, 0xD9,
0xCF, 0x46, 0x52, 0xE9, 0xEF, 0xDB, 0x72, 0xD7,
0x45, 0x40, 0xA4, 0x2B, 0xDE, 0x6D, 0x78, 0x36,
0xD5, 0x9A, 0x5C, 0xEA, 0xAE, 0xF3, 0x10, 0x53,
0x25, 0xB2, 0x07, 0x2F},
.iv = {0x00, 0xE0, 0x01, 0x7B, 0x27, 0x77, 0x7F, 0x3F,
0x4A, 0x17, 0x86, 0xF0, 0x00, 0x00, 0x00, 0x01},
.size = 36
};
CTR<AES128> ctraes128;
byte buffer[128];
bool testCipher_N(Cipher *cipher, const struct TestVector *test, size_t inc)
{
byte output[MAX_CIPHERTEXT_SIZE];
size_t posn, len;
cipher->clear();
if (!cipher->setKey(test->key, cipher->keySize())) {
Serial.print("setKey ");
return false;
}
if (!cipher->setIV(test->iv, cipher->ivSize())) {
Serial.print("setIV ");
return false;
}
memset(output, 0xBA, sizeof(output));
for (posn = 0; posn < test->size; posn += inc) {
len = test->size - posn;
if (len > inc)
len = inc;
cipher->encrypt(output + posn, test->plaintext + posn, len);
}
if (memcmp(output, test->ciphertext, test->size) != 0) {
Serial.print(output[0], HEX);
Serial.print("->");
Serial.print(test->ciphertext[0], HEX);
return false;
}
cipher->setKey(test->key, cipher->keySize());
cipher->setIV(test->iv, cipher->ivSize());
for (posn = 0; posn < test->size; posn += inc) {
len = test->size - posn;
if (len > inc)
len = inc;
cipher->decrypt(output + posn, test->ciphertext + posn, len);
}
if (memcmp(output, test->plaintext, test->size) != 0)
return false;
return true;
}
void testCipher(Cipher *cipher, const struct TestVector *test)
{
bool ok;
Serial.print(test->name);
Serial.print(" ... ");
ok = testCipher_N(cipher, test, test->size);
ok &= testCipher_N(cipher, test, 1);
ok &= testCipher_N(cipher, test, 2);
ok &= testCipher_N(cipher, test, 5);
ok &= testCipher_N(cipher, test, 8);
ok &= testCipher_N(cipher, test, 13);
ok &= testCipher_N(cipher, test, 16);
if (ok)
Serial.println("Passed");
else
Serial.println("Failed");
}
void perfCipherEncrypt(const char *name, Cipher *cipher, const struct TestVector *test)
{
unsigned long start;
unsigned long elapsed;
int count;
Serial.print(name);
Serial.print(" ... ");
cipher->setKey(test->key, cipher->keySize());
cipher->setIV(test->iv, cipher->ivSize());
start = micros();
for (count = 0; count < 500; ++count) {
cipher->encrypt(buffer, buffer, sizeof(buffer));
}
elapsed = micros() - start;
Serial.print(elapsed / (sizeof(buffer) * 500.0));
Serial.print("us per byte, ");
Serial.print((sizeof(buffer) * 500.0 * 1000000.0) / elapsed);
Serial.println(" bytes per second");
}
void perfCipherDecrypt(const char *name, Cipher *cipher, const struct TestVector *test)
{
unsigned long start;
unsigned long elapsed;
int count;
Serial.print(name);
Serial.print(" ... ");
cipher->setKey(test->key, cipher->keySize());
cipher->setIV(test->iv, cipher->ivSize());
start = micros();
for (count = 0; count < 500; ++count) {
cipher->decrypt(buffer, buffer, sizeof(buffer));
}
elapsed = micros() - start;
Serial.print(elapsed / (sizeof(buffer) * 500.0));
Serial.print("us per byte, ");
Serial.print((sizeof(buffer) * 500.0 * 1000000.0) / elapsed);
Serial.println(" bytes per second");
}
void setup()
{
Serial.begin(9600);
Serial.println();
Serial.println("Test Vectors:");
testCipher(&ctraes128, &testVectorAES128CTR1);
testCipher(&ctraes128, &testVectorAES128CTR2);
testCipher(&ctraes128, &testVectorAES128CTR3);
Serial.println();
Serial.println("Performance Tests:");
perfCipherEncrypt("AES-128-CTR Encrypt", &ctraes128, &testVectorAES128CTR1);
perfCipherDecrypt("AES-128-CTR Decrypt", &ctraes128, &testVectorAES128CTR1);
}
void loop()
{
}