/// <summary>
/// Creates the encrypted Datagram.
/// Client provides the encryption method to use as <typeparam name="T">SymmetricAlgorithm</typeparam>.
/// </summary>
/// <param name="key"></param>
/// <param name="salt"></param>
/// <returns></returns>
public string CreateGramContent <T>(string key, string salt)
where T : SymmetricAlgorithm, new()
{
DateTime Now = DateTime.Now.ToUniversalTime();
this._created = string.Format("{0:yyyy-MM-dd-TZ-HH:mm:ss.fff}", Now);
this._messageLength = this._message.Length;
StringBuilder SaltedMessage = new StringBuilder(this.Message);
Random r = new Random((int)DateTime.Now.Ticks);
int charCount = r.Next(3, 25);
for (int charIndex = 0; charIndex < charCount; charIndex++)
{
SaltedMessage.Append((char)r.Next(32, 90));
}
SecureGram work = new SecureGram(this);
work.IsCompressed = this._messageLength >= 10000;
if (work.IsCompressed)
{
MemoryStream messageCompressed = new MemoryStream();
using (var outGZipStream = new GZipStream(messageCompressed, CompressionLevel.Optimal))
{
using (StreamWriter sw = new StreamWriter(outGZipStream))
{
sw.Write(SaltedMessage.ToString());
sw.Close();
}
}
work.Message = Convert.ToBase64String(messageCompressed.ToArray());
}
CipherUtility cipher = new CipherUtility(new T());
return
(cipher.Encrypt(
ObjectJsonSerializer <SecureGram> .CreateDocumentFormat(work),
key,
salt,
Base64FormattingOptions.InsertLineBreaks));
}
/// <summary>
/// Takes a string with the content of the encrypted message, and decrypts/decompresses/validates the content.
/// Client provides the encryption method to use as <typeparam name="T">SymmetricAlgorithm</typeparam>.
/// </summary>
/// <param name="encryptedContent"></param>
/// <param name="key"></param>
/// <param name="salt"></param>
public void LoadGramContent <T>(string encryptedContent, string key, string salt)
where T : SymmetricAlgorithm, new()
{
CipherUtility cipher = new CipherUtility(new T());
this.Load(
ObjectJsonSerializer <SecureGram> .CreateObjectFormat(
cipher.Decrypt(
encryptedContent,
key,
salt)));
if (this._isCompressed)
{
MemoryStream messageCompressed = new MemoryStream(Convert.FromBase64String(this._message));
StringBuilder result = new StringBuilder();
using (var inGZipStream = new GZipStream(messageCompressed, CompressionMode.Decompress))
{
const int size = 16384;
byte[] buffer = new byte[size];
int count = 0;
int TotalWritten = 0;
while (TotalWritten < this._messageLength)
{
count = inGZipStream.Read(buffer, 0, size);
if (TotalWritten + count > this._messageLength)
{
count = this._messageLength - TotalWritten;
}
for (int index = 0; index < count; index++)
{
result.Append((char)buffer[index]);
}
TotalWritten += count;
}
}
this._message = result.ToString();
}
}
