//does encryption and decryption and returns a filled testResult
private TestResult process(String message)
{
TestResult testResult = new TestResult();
//encryption
stopWatch.Start();
byte[] plainMessageBytes = Encoding.UTF8.GetBytes(message); //convert message to byte array
Tuple <byte[], byte[]> res = CryptoUtility.AESEncrypt(plainMessageBytes, AESKey); //encrypts data
//extract results
byte[] encMessageBytes = res.Item1; //gets encrypted bytes from tuple
byte[] IV = res.Item2; //gets initialisation vector from tuple
stopWatch.Stop();
testResult.encryptionTime = (int)stopWatch.ElapsedMilliseconds; //store time taken
testResult.totalLength = encMessageBytes.Length; //store length of encrypted message
//decryption//
stopWatch.Reset();
stopWatch.Start();
//passes back encrypted message, key and initialisation vector to decrypt it
string decryptedMessage = CryptoUtility.AESDecrypt(encMessageBytes, AESKey, IV);
stopWatch.Stop();
testResult.decryptionTime = (int)stopWatch.ElapsedMilliseconds;
//check that nothing went wrong
if (0 != String.Compare(decryptedMessage, message))
{
throw new Exception("something ain't right");
}
testResult.totalTime = testResult.encryptionTime + testResult.decryptionTime; //adds up total time
return(testResult);
}
/// <summary>
/// Returns the key whos date field is equal to todays date. If a key does not yet exist for todays date, it is created
/// and stored.
/// </summary>
/// <returns>byte[] containing todays key</returns>
public Key getTodaysKey()
{
SQLiteDataReader reader = db.retrieve("SELECT keyID, AESKey, IV FROM Keys WHERE date = CURRENT_DATE"); //gets key with todays date
if (reader.HasRows) //if there were any keys with todays date
{
reader.Read(); //prepares reader to extract data
int keyID = Convert.ToInt32((long)reader["keyID"]); //sqlite stored primary keys as int64s
byte[] encKey = (byte[])reader["AESKey"]; //extract encrypted key
byte[] IV = (byte[])reader["IV"]; //extract initialisation vector it was encrypted with
byte[] keyBytes = decryptKey(encKey, IV); //decrypt key
Key key = new Key(keyID, keyBytes); //creates key object to return
return(key);
}
else //must generate new key and create DB entry
{
byte[] newKey = CryptoUtility.GenerateAESRandomKey(); //generate random AES key
byte[] masterKey = Globals.getMasterKey(); //gets master key to encrypt the new key
Tuple <byte[], byte[]> encResult = CryptoUtility.AESEncrypt(newKey, masterKey); //encrypts new key with master key
byte[] encNewKey = encResult.Item1; //extract encrypted key
byte[] IV = encResult.Item2; //extract initialisation vector
insertNewKey(encNewKey, IV); //insert it into database
return(getTodaysKey()); //1 level of recursion, creates entry then fetches and returns it
}
}
//this method tests the creation of a random AES key, then using it encrypt and decrypt a message
public void testRandomKeyEncryption()
{
string data = "hello, good morning, I hope all is well. blahblahblahblahblah";
byte[] dataBytes = Encoding.UTF8.GetBytes(data); //convert data to bytes
byte[] keyBytes = CryptoUtility.GenerateAESRandomKey(); //gets randomly generated
//tuple contains encrypted bytes plus initialisation vector needed to decrypt it
Tuple <byte[], byte[]> enc = CryptoUtility.AESEncrypt(dataBytes, keyBytes); //encypts and gets encrypted bytes + IV
byte[] encBytes = enc.Item1; //encrypted bytes
byte[] IV = enc.Item2; //Instantiation vector
string decryptedString = CryptoUtility.AESDecrypt(encBytes, keyBytes, IV);
Assert.AreEqual <string>(data, decryptedString); //compare original data to the decrypted string
}
/// <summary>
/// Takes message (which must have sender/recipient set) and stores it in the database.
/// </summary>
/// <param name="message">Message to store</param>
public void commitMessage(Message message)
{
Boolean sent = false; //was received
if (message.target != 0) //was sent
{
sent = true;
}
int conversationID; //ID of User the message was exchanged with
if (sent) //was sent by this application
{
conversationID = message.target; //get ID of who it was sent to (ID of sender would be zero - aka local)
}
else //wat received by this applicaiton
{
conversationID = message.sender; //gets ID of sender (ID of target would be zero - aka local)
}
Key key = keyManager.getTodaysKey(); //get key being used at time of inserting message
byte[] plainMessageBytes = Encoding.UTF8.GetBytes(message.message); //convert message text into byte array
Tuple <byte[], byte[]> encResult = CryptoUtility.AESEncrypt(plainMessageBytes, key.keyBytes); //encrypt message with todays key
byte[] encMessage = encResult.Item1; //extract encrypted message
byte[] IV = encResult.Item2; //extract initialisation vector
int keyID = key.keyID;
key = null; //let the key bytes be garbage collected.
//runs query and passes blobs to store message
db.messageInsert($"INSERT INTO Messages (conversationID, sent, message, keyID, IV) VALUES (\"{conversationID}\",\"{sent}\",@message,\"{keyID}\",@IV)", encMessage, IV);
//string messageString = message.message;
//run query to store it
//db.update($"INSERT INTO Messages (conversationID, sent, message) VALUES (\"{conversationID}\",\"{sent}\",\"{messageString}\")");
}
/// <summary>
/// AES 加密(高级加密标准，是下一代的加密算法标准，速度快，安全级别高，目前 AES 标准的一个实现是 Rijndael 算法)
/// </summary>
/// <param name="encryptString">待加密密文</param>
/// <param name="encryptKey">加密密钥</param>
/// <returns></returns>
public static string AESEncrypt(this string encryptString, string encryptKey)
{
return(CryptoUtility.AESEncrypt(encryptString, encryptKey));
}
