Hello all,
I am having a problem where I get an error message when I call
FlushFinalBlock when decrypting my encrypted text. I am using the
Rijndael algorithm.
The error message is "Length of the data to decrypt is invalid" and
occurs on the csDecrypt.FlushFinalBlock.
Please find below the two routines I use to encrypt my text and decrypt
the text. I have used the two routines in a very simple app that takes
a string from a label and then calls EncryptString and displays it on
another label. I then call DecryptString and pass it the contents of
the encrypted label text property.
The CryptKey is byte[32] and is set on creation of the object
containing these methods.
Could somebody please enlighten me as to what I am doing wrong!
Thanks in advance
Jimski
public string EncryptString(string pText)
{
string strResult = "";
try
{
// Create the rijndael encryptor
ICryptoTransform encryptor =
_RijndaelEncryptor.CreateEncryptor();
// Encrypt the data to the memory stream
MemoryStream msEncrypt = new MemoryStream(pText.Length);
CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor,
CryptoStreamMode.Write);
// Convert the string to a byte array.
byte[] beforeEncrypt = Encoding.UTF8.GetBytes(pText);
// Write all the data to the crypto stream and flush it to the
MemoryStream.
csEncrypt.Write(beforeEncrypt, 0, beforeEncrypt.Length);
csEncrypt.FlushFinalBlock();
// Read encrypted array of bytes from the MemoryStream
byte[] afterEncrypt = new byte[msEncrypt.Length];
msEncrypt.Position = 0;
msEncrypt.Read(afterEncrypt, 0, afterEncrypt.Length);
csEncrypt.Close();
// Returns the encrypted text as a string
strResult = Encoding.UTF8.GetString(afterEncrypt);
}
catch (Exception ex)
{
// An error occurred during encryption
}
return strResult;
}
public string DecryptString(string pEncryptedText)
{
string strResult = "";
try
{
// Convert the string to a byte array.
byte[] beforeDecrypt = Encoding.UTF8.GetBytes(pEncryptedText);
// Create the rijndael decryptor
ICryptoTransform decryptor =
_RijndaelEncryptor.CreateDecryptor();
// decrypt the data to the memory stream
MemoryStream msDecrypt = new
MemoryStream(beforeDecrypt.Length);
CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor,
CryptoStreamMode.Write);
// Write all the data to the crypto stream and flush it.
csDecrypt.Write(beforeDecrypt, 0, beforeDecrypt.Length);
// ERROR occurs in this next line.
csDecrypt.FlushFinalBlock();
// Read decrypted array of bytes from the MemoryStream
byte[] afterDecrypt = new byte[msDecrypt.Length];
msDecrypt.Position = 0;
msDecrypt.Read(afterDecrypt, 0, afterDecrypt.Length);
csDecrypt.Close();
// Returns the decrypted text as a string
strResult = Encoding.UTF8.GetString(afterDecrypt);
}
catch (Exception ex)
{
// Show error - which in this case is "Length of the data to
decrypt is invalid"
}
return strResult;
} 3 29157
Here's a sample that can should help: http://www.dalepreston.com/Blog/Arch...0_Archive.html
DalePres
MCAD, MCDBA, MCSE
"Jimski" <ji**********@gmail.com> wrote in message
news:11**********************@f14g2000cwb.googlegr oups.com... Hello all,
I am having a problem where I get an error message when I call FlushFinalBlock when decrypting my encrypted text. I am using the Rijndael algorithm.
The error message is "Length of the data to decrypt is invalid" and occurs on the csDecrypt.FlushFinalBlock.
Please find below the two routines I use to encrypt my text and decrypt the text. I have used the two routines in a very simple app that takes a string from a label and then calls EncryptString and displays it on another label. I then call DecryptString and pass it the contents of the encrypted label text property.
The CryptKey is byte[32] and is set on creation of the object containing these methods.
Could somebody please enlighten me as to what I am doing wrong!
Thanks in advance
Jimski public string EncryptString(string pText) { string strResult = "";
try { // Create the rijndael encryptor ICryptoTransform encryptor = _RijndaelEncryptor.CreateEncryptor();
// Encrypt the data to the memory stream MemoryStream msEncrypt = new MemoryStream(pText.Length); CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write);
// Convert the string to a byte array. byte[] beforeEncrypt = Encoding.UTF8.GetBytes(pText);
// Write all the data to the crypto stream and flush it to the MemoryStream. csEncrypt.Write(beforeEncrypt, 0, beforeEncrypt.Length); csEncrypt.FlushFinalBlock();
// Read encrypted array of bytes from the MemoryStream byte[] afterEncrypt = new byte[msEncrypt.Length]; msEncrypt.Position = 0; msEncrypt.Read(afterEncrypt, 0, afterEncrypt.Length);
csEncrypt.Close();
// Returns the encrypted text as a string strResult = Encoding.UTF8.GetString(afterEncrypt); } catch (Exception ex) { // An error occurred during encryption } return strResult; }
public string DecryptString(string pEncryptedText) { string strResult = "";
try { // Convert the string to a byte array. byte[] beforeDecrypt = Encoding.UTF8.GetBytes(pEncryptedText);
// Create the rijndael decryptor ICryptoTransform decryptor = _RijndaelEncryptor.CreateDecryptor();
// decrypt the data to the memory stream MemoryStream msDecrypt = new MemoryStream(beforeDecrypt.Length); CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Write);
// Write all the data to the crypto stream and flush it. csDecrypt.Write(beforeDecrypt, 0, beforeDecrypt.Length); // ERROR occurs in this next line. csDecrypt.FlushFinalBlock();
// Read decrypted array of bytes from the MemoryStream byte[] afterDecrypt = new byte[msDecrypt.Length]; msDecrypt.Position = 0; msDecrypt.Read(afterDecrypt, 0, afterDecrypt.Length);
csDecrypt.Close();
// Returns the decrypted text as a string strResult = Encoding.UTF8.GetString(afterDecrypt); } catch (Exception ex) { // Show error - which in this case is "Length of the data to decrypt is invalid" }
return strResult; }
Thanks Dale,
Your code identified an area that I was implementing wrong.
In my decryption routine I should have populated the memory stream with
the bytes and then created the CryptoStream. Writing them afterwards
was causing problems.
Cheers for you help.
Jimski
I am glad it helped. That's what makes it worth the time to write it.
DalePres
"Jimski" <ji**********@gmail.com> wrote in message
news:11**********************@l41g2000cwc.googlegr oups.com... Thanks Dale,
Your code identified an area that I was implementing wrong.
In my decryption routine I should have populated the memory stream with the bytes and then created the CryptoStream. Writing them afterwards was causing problems.
Cheers for you help. Jimski This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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