CryptoStream.Read Method error when decrypting

[James]

Hi,
I am developing a ActiveX Control which will be used in a web page.
The control will encrypt some value then decrypt it when the web page opens
next time.
I tested the control in a windows application and it works fine and no error
jumps.
However, when I tried to use it in a web page, problems came.
There is no problem for encrypting but the decrypting can't be finished.
The error jumped from the line below

csDecrypt.Read( fromEncrypt, 0, fromEncrypt.Len gth);

and the error message reads as below:
PKCS7 padding is invalid and cannot be removed.

I tested again in the windows application but I couldn't trigger the error.
Does any one know why this CryptoStream.Re ad Method behaves differently
in a web browser?


Please see code details below.

protected string DecryptInk(byte[] key,byte[] IV,String Ink64String)
{
ASCIIEncoding textConverter= new ASCIIEncoding() ;
RijndaelManaged myRijndael=new RijndaelManaged ();
byte[] fromEncrypt;
byte[] encrypted;
string decryptedStr;

//Get a decryptor that uses the same key and IV as the encryptor.
ICryptoTransfor m decryptor = myRijndael.Crea teDecryptor(key , IV);

encrypted=Conve rt.FromBase64St ring(Ink64Strin g);

MemoryStream msDecrypt = new MemoryStream(en crypted);
CryptoStream csDecrypt = new CryptoStream(ms Decrypt, decryptor,
CryptoStreamMod e.Read);

fromEncrypt = new byte[encrypted.Lengt h];
try
{
//problem is here!!
csDecrypt.Read( fromEncrypt, 0, fromEncrypt.Len gth);
}
catch (System.Excepti on exp)
{
MessageBox.Show (exp.Message,ex p.Source,Messag eBoxButtons.OK) ;
return String.Empty;
}
decryptedStr=te xtConverter.Get String(fromEncr ypt);

///remove \0 or null reference from the end of the string.
decryptedStr=de cryptedStr.Trim End(Char.Parse( "\0"));
//return the decrypted string.
return decryptedStr;
}

[James]

RE: CryptoStream.Re ad Method error when decrypting

I found the problem.
I passed wrong key and IV which caused an error.


"James" wrote:
[color=blue]
> Hi,
> I am developing a ActiveX Control which will be used in a web page.
> The control will encrypt some value then decrypt it when the web page opens
> next time.
> I tested the control in a windows application and it works fine and no error
> jumps.
> However, when I tried to use it in a web page, problems came.
> There is no problem for encrypting but the decrypting can't be finished.
> The error jumped from the line below
>
> csDecrypt.Read( fromEncrypt, 0, fromEncrypt.Len gth);
>
> and the error message reads as below:
> PKCS7 padding is invalid and cannot be removed.
>
> I tested again in the windows application but I couldn't trigger the error.
> Does any one know why this CryptoStream.Re ad Method behaves differently
> in a web browser?
>
>
> Please see code details below.
>
> protected string DecryptInk(byte[] key,byte[] IV,String Ink64String)
> {
> ASCIIEncoding textConverter= new ASCIIEncoding() ;
> RijndaelManaged myRijndael=new RijndaelManaged ();
> byte[] fromEncrypt;
> byte[] encrypted;
> string decryptedStr;
>
> //Get a decryptor that uses the same key and IV as the encryptor.
> ICryptoTransfor m decryptor = myRijndael.Crea teDecryptor(key , IV);
>
> encrypted=Conve rt.FromBase64St ring(Ink64Strin g);
>
> MemoryStream msDecrypt = new MemoryStream(en crypted);
> CryptoStream csDecrypt = new CryptoStream(ms Decrypt, decryptor,
> CryptoStreamMod e.Read);
>
> fromEncrypt = new byte[encrypted.Lengt h];
> try
> {
> //problem is here!!
> csDecrypt.Read( fromEncrypt, 0, fromEncrypt.Len gth);
> }
> catch (System.Excepti on exp)
> {
> MessageBox.Show (exp.Message,ex p.Source,Messag eBoxButtons.OK) ;
> return String.Empty;
> }
> decryptedStr=te xtConverter.Get String(fromEncr ypt);
>
> ///remove \0 or null reference from the end of the string.
> decryptedStr=de cryptedStr.Trim End(Char.Parse( "\0"));
> //return the decrypted string.
> return decryptedStr;
> }[/color]

[David Whitchurch-Bennett]

RE: CryptoStream.Re ad Method error when decrypting

I'm not sure if you are having these problems, but I have solved a similar
problem that has been troubling me all afternoon....

If you are converting bytes to text using an ASCIIEncoder, or any other
8-bit encoder, it will only convert using 8-bits, i.e. a byte value of 129
will become 1!!

I had this problem because the MSDN sample uses an ASCII encoder! How
annoying!!!!! I hope this helps.

"James" wrote:
[color=blue]
> I found the problem.
> I passed wrong key and IV which caused an error.
>
>
> "James" wrote:
>[color=green]
> > Hi,
> > I am developing a ActiveX Control which will be used in a web page.
> > The control will encrypt some value then decrypt it when the web page opens
> > next time.
> > I tested the control in a windows application and it works fine and no error
> > jumps.
> > However, when I tried to use it in a web page, problems came.
> > There is no problem for encrypting but the decrypting can't be finished.
> > The error jumped from the line below
> >
> > csDecrypt.Read( fromEncrypt, 0, fromEncrypt.Len gth);
> >
> > and the error message reads as below:
> > PKCS7 padding is invalid and cannot be removed.
> >
> > I tested again in the windows application but I couldn't trigger the error.
> > Does any one know why this CryptoStream.Re ad Method behaves differently
> > in a web browser?
> >
> >
> > Please see code details below.
> >
> > protected string DecryptInk(byte[] key,byte[] IV,String Ink64String)
> > {
> > ASCIIEncoding textConverter= new ASCIIEncoding() ;
> > RijndaelManaged myRijndael=new RijndaelManaged ();
> > byte[] fromEncrypt;
> > byte[] encrypted;
> > string decryptedStr;
> >
> > //Get a decryptor that uses the same key and IV as the encryptor.
> > ICryptoTransfor m decryptor = myRijndael.Crea teDecryptor(key , IV);
> >
> > encrypted=Conve rt.FromBase64St ring(Ink64Strin g);
> >
> > MemoryStream msDecrypt = new MemoryStream(en crypted);
> > CryptoStream csDecrypt = new CryptoStream(ms Decrypt, decryptor,
> > CryptoStreamMod e.Read);
> >
> > fromEncrypt = new byte[encrypted.Lengt h];
> > try
> > {
> > //problem is here!!
> > csDecrypt.Read( fromEncrypt, 0, fromEncrypt.Len gth);
> > }
> > catch (System.Excepti on exp)
> > {
> > MessageBox.Show (exp.Message,ex p.Source,Messag eBoxButtons.OK) ;
> > return String.Empty;
> > }
> > decryptedStr=te xtConverter.Get String(fromEncr ypt);
> >
> > ///remove \0 or null reference from the end of the string.
> > decryptedStr=de cryptedStr.Trim End(Char.Parse( "\0"));
> > //return the decrypted string.
> > return decryptedStr;
> > }[/color][/color]

[David Whitchurch-Bennett]

RE: CryptoStream.Re ad Method error when decrypting

I'm not sure if you are having these problems, but I have solved a similar
problem that has been troubling me all afternoon....

If you are converting bytes to text using an ASCIIEncoder, or any other
8-bit encoder, it will only convert using 8-bits, i.e. a byte value of 129
will become 1!!

I had this problem because the MSDN sample uses an ASCII encoder! How
annoying!!!!! I hope this helps.

"James" wrote:
[color=blue]
> I found the problem.
> I passed wrong key and IV which caused an error.
>
>
> "James" wrote:
>[color=green]
> > Hi,
> > I am developing a ActiveX Control which will be used in a web page.
> > The control will encrypt some value then decrypt it when the web page opens
> > next time.
> > I tested the control in a windows application and it works fine and no error
> > jumps.
> > However, when I tried to use it in a web page, problems came.
> > There is no problem for encrypting but the decrypting can't be finished.
> > The error jumped from the line below
> >
> > csDecrypt.Read( fromEncrypt, 0, fromEncrypt.Len gth);
> >
> > and the error message reads as below:
> > PKCS7 padding is invalid and cannot be removed.
> >
> > I tested again in the windows application but I couldn't trigger the error.
> > Does any one know why this CryptoStream.Re ad Method behaves differently
> > in a web browser?
> >
> >
> > Please see code details below.
> >
> > protected string DecryptInk(byte[] key,byte[] IV,String Ink64String)
> > {
> > ASCIIEncoding textConverter= new ASCIIEncoding() ;
> > RijndaelManaged myRijndael=new RijndaelManaged ();
> > byte[] fromEncrypt;
> > byte[] encrypted;
> > string decryptedStr;
> >
> > //Get a decryptor that uses the same key and IV as the encryptor.
> > ICryptoTransfor m decryptor = myRijndael.Crea teDecryptor(key , IV);
> >
> > encrypted=Conve rt.FromBase64St ring(Ink64Strin g);
> >
> > MemoryStream msDecrypt = new MemoryStream(en crypted);
> > CryptoStream csDecrypt = new CryptoStream(ms Decrypt, decryptor,
> > CryptoStreamMod e.Read);
> >
> > fromEncrypt = new byte[encrypted.Lengt h];
> > try
> > {
> > //problem is here!!
> > csDecrypt.Read( fromEncrypt, 0, fromEncrypt.Len gth);
> > }
> > catch (System.Excepti on exp)
> > {
> > MessageBox.Show (exp.Message,ex p.Source,Messag eBoxButtons.OK) ;
> > return String.Empty;
> > }
> > decryptedStr=te xtConverter.Get String(fromEncr ypt);
> >
> > ///remove \0 or null reference from the end of the string.
> > decryptedStr=de cryptedStr.Trim End(Char.Parse( "\0"));
> > //return the decrypted string.
> > return decryptedStr;
> > }[/color][/color]