/// <summary>
/// Sends a message to a specific user on the server
/// </summary>
/// <param name="email">Email of user </param>
/// <param name="plaintext">Text message to be sent </param>
/// <returns></returns>
private async Task SendMsg(string email, string plaintext)
{
try
{
//Check if we have the public key on our disk
var pos = Directory.GetCurrentDirectory().LastIndexOf("\\");
var filename = Directory.GetCurrentDirectory().Substring(0, pos) + "\\" + email + ".key";
if (!File.Exists(filename))
{
Console.WriteLine("Key does not exist for " + email + "\n");
}
else
{
//encide text message and decrypt using RSA formula
var textBytes = Encoding.ASCII.GetBytes(plaintext);
var bigInt = new BigInteger(textBytes);
var key = File.ReadAllText(filename);
//e, E, n, N extraction
byte[] keyBytes = Convert.FromBase64String(key);
var eSize = new byte[4];
for (var i = 0; i < 4; i++)
{
eSize[i] = keyBytes[i];
}
//if (BitConverter.IsLittleEndian)
// Array.Reverse(eSize);
var e = BitConverter.ToInt32(eSize, 0);
var bytes = new byte[e];
for (var i = 4; i < (4 + e); i++)
{
bytes[i - 4] = keyBytes[i];
}
BigInteger E = new BigInteger(bytes);
var nSize = new byte[4];
for (var i = 4 + e; i < 4 + e + 4; i++)
{
nSize[i - 4 - e] = keyBytes[i];
}
//if (BitConverter.IsLittleEndian)
// Array.Reverse(nSize);
var n = BitConverter.ToInt32(nSize, 0);
var nBytes = new byte[n];
for (var i = 0; i < n; i++)
{
nBytes[i] = keyBytes[i + 4 + e + 4];
}
BigInteger N = new BigInteger(nBytes);
//Final decryption of text
var cipher = BigInteger.ModPow(bigInt, E, N);
var cipherArray = cipher.ToByteArray();
var message = Convert.ToBase64String(cipherArray);
var textObj = new TextMessage();
textObj.email = email;
textObj.content = message;
var jsonText = JObject.FromObject(textObj);
//PUT request sends a JSON object
var content = new StringContent(jsonText.ToString(), Encoding.UTF8, "application/json");
var response = await client.PutAsync("http://kayrun.cs.rit.edu:5000/Message/" + email, content);
if (!response.IsSuccessStatusCode)
{
Console.WriteLine("Unable to send Message");
}
else
{
Console.WriteLine("Message written");
}
}
}
catch (HttpRequestException e)
{
Console.WriteLine("exception!\n" + e.Message);
}
}
public TextMessage(TextMessage savedMessage)
{
body = savedMessage.body;
authorId = savedMessage.authorId;
datetime = savedMessage.datetime;
}
