I am working in a C# application. We have common methods to store data on a file. These methods encrypt the data and store them on the file system. when we need the data, ReadData method decrypts the data and returns me plain text.
This code works fine in normal cases if size of the text in small. but for a example text given below, the decryption code is throwing exception - length of the data to decrypt is invalid.
The exception occurs at line
// close the CryptoStream
x_cryptostream.Close();
I tried different ways but no luck. Can some pls help.
Why am I encrypting already encrypted data - I am just trying to store in a file using common method of the huge application. The common methods storedata(key,data)
nad readdata(key)
do the encryption/decryption I can't avoid.
public static byte[] Decrypt(byte[] ciphertext, string Key, string IV)
{
byte[] k = Encoding.Default.GetBytes(Key);
byte[] iv = Encoding.Default.GetBytes(IV);
// create the encryption algorithm
SymmetricAlgorithm x_alg = SymmetricAlgorithm.Create("Rijndael");
x_alg.Padding = PaddingMode.PKCS7;
// create an ICryptoTransform that can be used to decrypt data
ICryptoTransform x_decryptor = x_alg.CreateDecryptor(k, iv);
// create the memory stream
MemoryStream x_memory_stream = new MemoryStream();
// create the CryptoStream that ties together the MemoryStream and the
// ICryptostream
CryptoStream x_cryptostream = new CryptoStream(x_memory_stream,
x_decryptor, CryptoStreamMode.Write);
// write the ciphertext out to the cryptostream
x_cryptostream.Write(ciphertext, 0, ciphertext.Length);
// close the CryptoStream
x_cryptostream.Close();
// get the plaintext from the MemoryStream
byte[] x_plaintext = x_memory_stream.ToArray();
Below is the code of encrypt method.
public static byte[] Encrypt(string strplain, string Key, string IV)
{
byte[] k = Encoding.Default.GetBytes(Key);
byte[] iv = Encoding.Default.GetBytes(IV);
byte[] plaintext = Encoding.Default.GetBytes(strplain);
// create the encryption algorithm
SymmetricAlgorithm x_alg = SymmetricAlgorithm.Create("Rijndael");
x_alg.Padding = PaddingMode.PKCS7;
// create an ICryptoTransform that can be used to encrypt data
ICryptoTransform x_encryptor = x_alg.CreateEncryptor(k, iv);
// create the memory stream
MemoryStream x_memory_stream = new MemoryStream();
// create the CryptoStream that ties together the MemoryStream and
// the ICryptostream
CryptoStream x_cryptostream = new CryptoStream(x_memory_stream,
x_encryptor, CryptoStreamMode.Write);
// write the plaintext out to the cryptostream
x_cryptostream.Write(plaintext, 0, plaintext.Length);
// close the CryptoStream
x_cryptostream.Close();
// get the ciphertext from the MemoryStream
byte[] x_ciphertext = x_memory_stream.ToArray();
// close memory stream
x_memory_stream.Close();
// convert from array to string
string cipher_Tx = Encoding.Default.GetString(x_ciphertext,
0, x_ciphertext.Length);
x_encryptor.Dispose();
x_alg.Clear();
byte[] cipher = Encoding.Default.GetBytes(cipher_Tx);
return cipher;
}
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