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Getting error Length of the data to decrypt is invalid [duplicate]

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;
}

Your problem is string cipher_Tx = Encoding.Default.GetString(x_ciphertext, 0, x_ciphertext.Length);.
x_ciphertext is not a valid byte representation of text, it has many unpresentable characters and when you do your byte[] to string conversion you are losing information. The correct way to do it is use a string format that is designed to represent binary data using something like Convert.ToBase64String(byte[]) and Convert.FromBase64String(string).
string cipher_Tx = Convert.ToBase64String(x_ciphertext)
x_encryptor.Dispose();
x_alg.Clear();
byte[] cipher = Convert.FromBase64String(cipher_Tx)
That being said, there is a lot of other "odd" things about your code, for example you don't use using statements and you really should. Also that whole conversion to string and back is totally unnecessary, just return x_ciphertext. There may be other problems with the code too (like where did the strings for Key and IV come from) and many other best practices (like you should be generating a random IV and writing it out in to the output and the key should be generated using a key derivation function not straight from user text), but I stopped checking after I found the string conversion issue.

Your code above works as long as the key and iv used to decrypt match the key and iv used to encrypt. Try this:
byte[] test = new byte[1000000];
for (int i = 0; i < 256; i++)
{
test[i] = (byte)i;
}
var ciphertext = Encrypt(Encoding.Default.GetString(test), "0000000000000000", "0000000000000000");
byte[] check = Decrypt(ciphertext, "0000000000000000", "0000000000000000");
for (int i = 0; i < 256; i++)
{
Debug.Assert(check[i] == (byte)i, "round trip");
}
As you can see, one million bytes encrypt and decrypt just fine with your code, so I don't think it has anything to do with data size.
However, change the IV like this:
byte[] check = Decrypt(ciphertext, "0000000000000000", "000000000000000X"); // note X
and the Debug.Assert will fire -- the decryption will not match. However, x_cryptostream.Close() succeeds.
Next, try changing the key like this:
byte[] check = Decrypt(ciphertext, "000000000000000X", "0000000000000000"); // note X
Now, x_cryptostream.Close() will fail with a CryptographicException, probably, "Padding is invalid and cannot be removed."
Corrupting the key will cause the decryption to fail, and x_cryptostream.Close() to fail.
I think the problem is in your saving and later restoring the key bytes.
BTW: Hopefully you are using the full binary range of the key, and not basing it only on ASCII characters, otherwise you don't really have a strong key.

Rijndael encrypted text causes length of data to decrypt is invalid error - C#

I have searched online but have not been able to find any solutions to my problem.
I am using previously written methods to encrypt and ecrypt text using the Rijndael class.
I use these functions to encrypt and decrypt usernames and emails for a web application I have been working on.
The encryption/decryption works perfectly, but every once in a while I get this error:
System.Security.Cryptography.CryptographicException: Length of the data to decrypt is invalid.
Currently, I am getting this error with a specific email address and I can't reproduce the error even if I replace some of the letters in the email.
Here are the encryption/decrytpion functions. The IV and Key are defined as read only strings.
static public string Encrypting(string Source)
{
byte[] bytIn = System.Text.ASCIIEncoding.ASCII.GetBytes(Source);
// create a MemoryStream so that the process can be done without I/O files
System.IO.MemoryStream ms = new System.IO.MemoryStream();
byte[] IVBytes = Encoding.ASCII.GetBytes(IV);
byte[] KEYBytes = Encoding.ASCII.GetBytes(KEY);
Rijndael rijndael = Rijndael.Create();
rijndael.IV = IVBytes;
rijndael.Key = KEYBytes;
// create Crypto Stream that transforms a stream using the encryption
CryptoStream cs = new CryptoStream(ms, rijndael.CreateEncryptor(), CryptoStreamMode.Write);
// write out encrypted content into MemoryStream
cs.Write(bytIn, 0, bytIn.Length);
cs.FlushFinalBlock();
// get the output and trim the '\0' bytes
byte[] bytOut = ms.GetBuffer();
int i = 0;
for (i = 0; i < bytOut.Length; i++)
if (bytOut[i] == 0)
break;
// convert into Base64 so that the result can be used in xml
return System.Convert.ToBase64String(bytOut, 0, i);
}
static public string Decrypting(string Source)
{
// convert from Base64 to binary
byte[] bytIn = System.Convert.FromBase64String(Source);
// create a MemoryStream with the input
System.IO.MemoryStream ms = new System.IO.MemoryStream(bytIn, 0, bytIn.Length);
byte[] IVBytes = Encoding.ASCII.GetBytes(IV);
byte[] KEYBytes = Encoding.ASCII.GetBytes(KEY);
Rijndael rijndael = Rijndael.Create();
rijndael.IV = IVBytes;
rijndael.Key = KEYBytes;
// create Crypto Stream that transforms a stream using the decryption
CryptoStream cs = new CryptoStream(ms, rijndael.CreateDecryptor(), CryptoStreamMode.Read);
// read out the result from the Crypto Stream
System.IO.StreamReader sr = new System.IO.StreamReader(cs);
return sr.ReadToEnd();
}
FYI - I am very new to cryptography and security.
Can these functions be fixed to avoid special cases that cause the error, or should I scrap these and use the RijndaelManaged class?
Sites I found that use RijndaelManaged:
SeeSharp
TekEye

The issue is almost certainly nothing to do with Rijndael vs. RijndaelManaged (or any other such implementation), but instead because the encrypted data contains a 0x00, and you are incorrectly assuming that the the ciphertext ends at the first 0x00 byte. Since the ciphertext can legitimately contain any byte value you should instead use the stream's Length property to determine the length of the ciphertext.
Eliminate the section you've commented: "get the output and trim the '\0' bytes" and replace the return ... statement with:
return System.Convert.ToBase64String(ms.GetBuffer(), 0, ms.Length);
It should be noted that there are many other issues with your use of cryptography here, e.g. the use of a key generated directly from the ASCII encoding of a string, and the fact you're using a fixed IV both negatively impact security.

The norm for the error is a padding issue. What version of .NET are you using? It is more common to use the AES classes (AES, or Advanced Encryption Standard, which is Rijndael). There are plenty of AES implementations you can find as samples.
If you need some proof AES is Rijndael: http://en.wikipedia.org/wiki/Advanced_Encryption_Standard

Creating Encryption Using string

Hi I'm just trying to encrypt a string but i want to reverse the decryption method to create exactly encrypted key
decryption was
public string newSample(string s)
{
byte[] buffer = Convert.FromBase64String(s);
Encoding utF8 = Encoding.UTF8;
byte[] bytes1 = utF8.GetBytes("key1");
byte[] bytes2 = utF8.GetBytes("key2");
RijndaelManaged rijndaelManaged1 = new RijndaelManaged();
rijndaelManaged1.Mode = CipherMode.CBC;
rijndaelManaged1.Padding = PaddingMode.Zeros;
rijndaelManaged1.BlockSize = 128;
rijndaelManaged1.KeySize = 128;
RijndaelManaged rijndaelManaged2 = rijndaelManaged1;
ICryptoTransform transform = (ICryptoTransform)null;
transform = rijndaelManaged2.CreateDecryptor(bytes2, bytes1);
byte[] bytes3 = (byte[])null;
using (MemoryStream memoryStream = new MemoryStream())
{
using (CryptoStream cryptoStream = new CryptoStream((Stream)memoryStream, transform, CryptoStreamMode.Write))
{
cryptoStream.Write(buffer, 0, buffer.GetLength(0));
cryptoStream.FlushFinalBlock();
}
rijndaelManaged2.Clear();
bytes3 = memoryStream.ToArray();
}
return new string(Encoding.UTF8.GetChars(bytes3));
}
is it possible to reverse the code and create encryption key ? if so
how could be the encryption should look lik for this decryption method ??
thanks

This is the problem - or at least the initial problem:
return new string(Encoding.UTF8.GetChars(bytes3));
The result of encryption is not a UTF-8-encoded byte array... it's arbitrary bytes. By assuming it's valid UTF-8-encoded text, you're losing information.
Instead, you should use a hex or base64 approach, both of which are designed to convert arbitrary binary data to text in a lossless fashion. For example:
return Convert.ToBase64String(bytes3);
Now, your decryption code should start with:
byte[] encryptedData = Convert.FromBase64String(base64EncryptedText);
(Where base64EncryptedText is the value returned from your encryption method.)
From there, it should be a matter of just reversing each step, and there are numerous examples around. You may well find that you've got a problem due to the padding mode, however - you may need to separately record the length of the original data.
As an aside, it's not clear why your method takes a string in the first place. It's odd for an encryption method to take a base64-encoded piece of data. It's more common for it to take either a normal plain text string which is converted into bytes using something like Encoding.UTF8, or for it to take a byte[] to start with.

Why are there random characters appearing in my decrypted text?

Intro
I'm trying to encrypt and decrypt texts and sometimes, especially for larger texts, random characters appear within the decrypted text. I'm using AES cryptography within the System.Security.Cryptography namespace and the text I'm trying to encrypt at the moment would be a URL and some info, such as the page title. I've provided an example below and what I've attempted. I've also written the two encryption and decryption methods, minus any lines that output to the Debug Window. The Key and IV used shouldn't be a problem as, for now, they would be constant.
I think it would be wise for me to point out that it encrypts and decrypts 18/01/2013;18/01/2013, in a separate occurrence, as expected.
Example
Say I wanted to decrypt this text:
Barnabe Googes Information & Homepage | Search and Research on BarnabeGooge.com;18/01/2013;18/01/2013;;http://www.googe.com
By default it uses UTF-8 and it would encrypt to:
뤟౏羜ڮ胂淺弊놛荧ꠃ錺槝ヸ蘜ầᄼꕒﾍ⍩㗪潺뱂施㒞ꨛ殳硪픴ی뿨춃�燲ᯁﱪ뙊힓琲鯖嶑⨹갂Ѭ쳀鿜�྄䋖⭫ퟂ㪏�荾ꆺשּ붹梾麦膛
And decrypts back to:
Barnabe Googes Information & Homepage | Search and Research on B���Ax2�!��f�M]18/01/20�;18/01[�;>َ�l?����m��*-��+��^A[=�
What I've attempted
I've attempted to change to other Encodings, but UTF-8 seem to affect the decrypted text the least.
Changed to different types of padding, but Padding.Zeros seems the best. I also can't use Padding.None because it throws a NotSupportedException: bad data length.
Changed the Mode to CBC (Not that it should matter).
Flush/Close CryptoStream so it could flush the final block, or something.
Just in case the fault rested with the title, I used WebUtility.HtmlDecode() to decode the title, but it didn't affect it.
Encryption Method
The encryption below uses AES Encryption, as you can see. I want to point out that key and IV are two global strings within the same class as both of the Encryption and Decryption methods. The reason I've done this is to mess around with different encodings and CryptographyServiceProviders, just if by chance a random change works. Please ignore these as they are constant and won't affect the final encryption/decryption.
public static byte[] EncryptStringToBytes(string plainText, Encoding Enc)
{
if (plainText == null || plainText.Length <= 0)
throw new ArgumentNullException("plainText");
byte[] encrypted;
using (AesCryptoServiceProvider tdsAlg = new AesCryptoServiceProvider())
{
tdsAlg.Key = (byte[])Enc.GetBytes(key).Take(tdsAlg.Key.Length).ToArray();
tdsAlg.IV = (byte[])Enc.GetBytes(IV).Take(tdsAlg.IV.Length).ToArray();
tdsAlg.Padding = PaddingMode.Zeros;
tdsAlg.Mode = CipherMode.CBC;
ICryptoTransform encryptor = tdsAlg.CreateEncryptor(tdsAlg.Key, tdsAlg.IV);
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
swEncrypt.Write(plainText);
}
encrypted = msEncrypt.ToArray();
csEncrypt.Close();
}
}
}
return encrypted;
}
Decryption Method
public static string DecryptStringFromBytes(byte[] cipherText,Encoding Enc)
{
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
string plaintext = null;
using (AesCryptoServiceProvider tdsAlg = new AesCryptoServiceProvider())
{
tdsAlg.Key = (byte[])Enc.GetBytes(key).Take(tdsAlg.Key.Length).ToArray();
tdsAlg.IV = (byte[])Enc.GetBytes(IV).Take(tdsAlg.IV.Length).ToArray() ;
tdsAlg.Padding = PaddingMode.Zeros;
tdsAlg.Mode = CipherMode.CBC;
ICryptoTransform decryptor = tdsAlg.CreateDecryptor();
using (MemoryStream msDecrypt = new MemoryStream(cipherText))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt,true))
{
plaintext = srDecrypt.ReadToEnd().Replace("\0","");
csDecrypt.Close();
return plaintext.Replace("\0",string.Empty);
}
}
}
}
return plaintext;
}
Bootnote
Just in case it matters, I'm using this to get the title of the webpage, but as I've mentioned using HtmlDecode doesn't affect it.
WebClient x = new WebClient();
string source = x.DownloadString(Url);
x.Dispose();
string title= Regex.Match(source, #"\<title\b[^>]*\>\s*(?<Title>[\s\S]*?)\</title\>", RegexOptions.IgnoreCase).Groups["Title"].Value;
title = title.Replace(";", " ");
return title;

Thanks to Hans Passant I found the solution. The problem was that I was using Encoding.GetString() or Encoding.GetBytes() when I was encrypting and decrypting, when I should have been using Convert.ToBase64String() or Convert.FromBase64String().

I had the same problem of extra output. For me it was not encoding-problem, because I was passing it as byte array in BCrypt library. As it is plain-text, I would use space-character as padding before encryption and trim after decryption.
int padding = BLOCK_SIZE - (input_len+1)%BLOCK_SIZE;
if(padding && (input_len+padding) <= buf_size)
{
memset(buf+input_len, ' ', padding);
input_len += padding;
}
For 128 bit encryption, the block-size is 16. Note that the buf_size should be multiple of the block-size to make it work all the time. As we padded the input already, we do not need the padding algorithm in decryption.
tdsAlg.Padding = PaddingMode.None;
And at the end of decryption, I would trim the output.

Encryption output always different even with same key

I'm trying to store a password in a file that I'd like to retrieve for later. Hashing is not an option as I need the password for connecting to a remote server for later.
The following code works well, but it creates a different output each time even though the key is the same. This is bad as when the application shuts down and restarts I won't be able to retrieve my password any more. How can I store passwords in a file and retrieve them later?
public class EncyptDecrypt {
static System.Security.Cryptography.TripleDESCryptoServiceProvider keyProv = new System.Security.Cryptography.TripleDESCryptoServiceProvider();
public static System.Security.Cryptography.TripleDESCryptoServiceProvider KeyProvider {
get {
keyProv.Key = new byte[] { /* redacted with prejudice */ };
return keyProv;
}
}
public static string Encrypt(string text, SymmetricAlgorithm key) {
if (text.Equals(string.Empty)) return text;
// Create a memory stream.
MemoryStream ms = new MemoryStream();
// Create a CryptoStream using the memory stream and the
// CSP DES key.
CryptoStream encStream = new CryptoStream(ms, key.CreateEncryptor(), CryptoStreamMode.Write);
// Create a StreamWriter to write a string
// to the stream.
StreamWriter sw = new StreamWriter(encStream);
// Write the plaintext to the stream.
sw.WriteLine(text);
// Close the StreamWriter and CryptoStream.
sw.Close();
encStream.Close();
// Get an array of bytes that represents
// the memory stream.
byte[] buffer = ms.ToArray();
// Close the memory stream.
ms.Close();
// Return the encrypted byte array.
return System.Convert.ToBase64String(buffer);
}
// Decrypt the byte array.
public static string Decrypt(string cypherText, SymmetricAlgorithm key) {
if (cypherText.Equals(string.Empty)) return cypherText;
string val;
try {
// Create a memory stream to the passed buffer.
MemoryStream ms = new MemoryStream(System.Convert.FromBase64String(cypherText));
// Create a CryptoStream using the memory stream and the
// CSP DES key.
CryptoStream encStream = new CryptoStream(ms, key.CreateDecryptor(), CryptoStreamMode.Read);
// Create a StreamReader for reading the stream.
StreamReader sr = new StreamReader(encStream);
// Read the stream as a string.
val = sr.ReadLine();
// Close the streams.
sr.Close();
encStream.Close();
ms.Close();
}
catch (System.Exception) {
return string.Empty;
}
return val;
}
}

I believe that what's happening is that the crypto provider is randomly generating an IV. Specify this and it should no longer differ.
Edit: You can do this in your 'keyProvider' by setting the IV property.

According to the docs of CreateEncryptor:
If the current IV property is a null
reference (Nothing in Visual Basic),
the GenerateIV method is called to
create a new random IV.
This will make the ciphertext different every time.
Note: a way around this is discussed here where I suggest you can prepend the plaintext with a mac ... then the first block of ciphertext is effectively the IV, but it's all repeatable

You need to specify an IV (initialization vector), even if you generate a random one. If you use random IV then you must store it along with the ciphertext so you can use it later on decryption, or you can derive an IV from some other data (for example if you're encrypting a password, you can derive the IV from the username).