private void btnDecrypt_Click(object sender, EventArgs e)
{
SymmetricCryptoProvider symmetricCrypt = new SymmetricCryptoProvider();
if (string.IsNullOrWhiteSpace(txtDecryptPassphrase.Text))
{
MessageBox.Show("Cannot decrypt without a passphrase", "Error", MessageBoxButtons.OK,
MessageBoxIcon.Error);
return;
}
string plaintext = "";
try
{
plaintext = symmetricCrypt.DecryptWithKey(txtCypertext.Text, txtDecryptPassphrase.Text);
}
catch (CryptographicException)
{
MessageBox.Show("Unable to decrypt with provided passphrase", "Error", MessageBoxButtons.OK,
MessageBoxIcon.Error);
return;
}
txtCypertext.Text = plaintext;
tabControl1.SelectTab(0);
}
public void Encrypt_Decrypt_ReturnsOriginalValue()
{
var crypto = new SymmetricCryptoProvider();
var cryptoText = crypto.EncryptWithKey(secret, password);
var original = crypto.DecryptWithKey(cryptoText, password);
Assert.AreEqual(secret, original);
}
public void Encrypt_Decrypt_Hash_ReturnsOriginalValue()
{
var crypto = new SymmetricCryptoProvider();
string hashedPassword = SymmetricCryptoProvider.GetSecureHashForString(password);
var cryptoText = crypto.EncryptWithKey(secret, hashedPassword);
var original = crypto.DecryptWithKey(cryptoText, hashedPassword);
Assert.AreEqual(secret, original);
}
public SelfDestructingMessage GetMessage(int messageId, string passphrase)
{
var db = new CryptAByteContext();
SelfDestructingMessage message = db.SelfDestructingMessages.SingleOrDefault(m => m.MessageId == messageId);
//.Include("SelfDestructingMessageAttachment")
if (message == null)
{
throw new ArgumentOutOfRangeException("messageId", "Message not found. Was it already read?");
}
var crypto = new SymmetricCryptoProvider();
try
{
message.Message = crypto.DecryptWithKey(message.Message, passphrase);
var attachment = db.SelfDestructingMessageAttachments.FirstOrDefault(a => a.MessageId == messageId);
if (attachment != null)
{
message.HasAttachment = true;
// todo: get filename here
}
}
catch (Exception)
{
throw new ArgumentOutOfRangeException("passphrase", "server error decrypting message");
}
message.Message = GzipCompression.Decompress(message.Message);
db.SelfDestructingMessages.Remove(message);
db.SaveChanges();
message.SelfDestructingMessageAttachment = new SelfDestructingMessageAttachment
{
// AttachmentName = attachmentName
};
return(message);
}
public SelfDestructingMessageAttachment GetAttachment(int messageId, string passphrase)
{
var db = new CryptAByteContext();
var crypto = new SymmetricCryptoProvider();
var attachment = db.SelfDestructingMessageAttachments.SingleOrDefault(m => m.MessageId == messageId);
if (attachment != null)
{
attachment.Attachment = crypto.DecryptWithKey(attachment.Attachment, passphrase);
db.SelfDestructingMessageAttachments.Remove(attachment);
// todo: move decompression to this class
}
db.SaveChanges();
return(attachment);
}
public void DeleteKeyWithPassphrase(string token, string passphrase)
{
var db = new CryptAByteContext();
var key = db.Keys.Include("Messages").SingleOrDefault(k => k.KeyToken == token);
if (key == null)
{
throw new ArgumentOutOfRangeException("Key for this token not found. Was it already deleted?");
}
var crypto = new SymmetricCryptoProvider();
try
{
var plaintext = crypto.DecryptWithKey(key.PrivateKey, passphrase);
}
catch (ArgumentException)
{
throw new ArgumentException("Failed to verify passphrase. A correct passphrase is required to verify the delete request.");
}
db.Keys.Remove(key);
db.SaveChanges();
}
