Beginning Crypto question

[SenseiHitokiri]

I have some code that converts a string into base64 for some
encryption.
It was written on the 1.1 framework but I am trying to get it to work
on 2.0. It throws exceptions on the cryptStream.Flu shFinalBlock() and
cryptStream.Cle ar(). Can anyone tell me what is up with this?
Thanks ahead of time for any help you can offer.

public static string EncryptAndBase6 4( string val )
{
byte[] buf = UnicodeEncoding .Unicode.GetByt es(val);

MemoryStream memStream = new MemoryStream();
CryptoStream cryptStream = new CryptoStream(me mStream, enc3des,
CryptoStreamMod e.Write);

cryptStream.Wri te(buf, 0, buf.Length);
cryptStream.Flu shFinalBlock();
cryptStream.Cle ar();
Array.Clear(buf , 0, buf.Length);

buf = memStream.GetBu ffer();
val = Convert.ToBase6 4String(buf, 0, (int)memStream. Length);
Array.Clear(buf , 0, (int)memStream. Length);
return val;
}

public static object DecryptFromBase 64( object val )
{
if( val.Equals( DBNull.Value ) )
return DBNull.Value;

return DecryptFromBase 64( (string)val );
}

public static string DecryptFromBase 64( string base64str )
{
byte[] buf = Convert.FromBas e64String(base6 4str);
MemoryStream memStream = new MemoryStream();
CryptoStream cryptStream = new CryptoStream(me mStream, dec3des,
CryptoStreamMod e.Write );

cryptStream.Wri te(buf, 0, buf.Length);
cryptStream.Flu shFinalBlock();
cryptStream.Cle ar();

Array.Clear(buf , 0, buf.Length);
buf = memStream.GetBu ffer();

string ret = UnicodeEncoding .Unicode.GetStr ing(buf, 0,
(int)memStream. Length);
Array.Clear(buf , 0, (int)memStream. Length);
memStream.Close ();

return ret;
}

[Jon Skeet [C# MVP]]

SenseiHitokiri <se************ @gmail.comwrote :

I have some code that converts a string into base64 for some
encryption.
It was written on the 1.1 framework but I am trying to get it to work
on 2.0. It throws exceptions on the cryptStream.Flu shFinalBlock() and
cryptStream.Cle ar(). Can anyone tell me what is up with this?
Thanks ahead of time for any help you can offer.

Could you post a short but complete program which demonstrates the
problem?

See http://www.pobox.com/~skeet/csharp/complete.html for details of
what I mean by that.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

[SenseiHitokiri]

hmm I swore I posted the code up in here but I don't see it. Well here
it is again. C#

using System;
using System.Security .Cryptography;
using System.Text;

namespace DebugCrypto
{
class DebugCrypto
{
static void Main(string[] args)
{
DebugCrypto x = new DebugCrypto();
Console.Read();
}
void Program()
{
string base64str = "FmcT1N0kYX/IId4m6GuYpg=="; //string to
decrypt
ICryptoTransfor m dec3des = SetupCrypto();
byte[] buf = Convert.FromBas e64String(base6 4str);

System.IO.Memor yStream memStream = new
System.IO.Memor yStream();
CryptoStream cryptStream = new CryptoStream(me mStream,
dec3des, CryptoStreamMod e.Write);

cryptStream.Wri te(buf, 0, buf.Length);
try
{
cryptStream.Flu shFinalBlock(); //This is what
errors out
cryptStream.Cle ar(); // and this
}
catch (Exception ex)
{
Console.WriteLi ne(ex.ToString( ));
}

Array.Clear(buf , 0, buf.Length);
buf = memStream.GetBu ffer();

Console.WriteLi ne(UnicodeEncod ing.Unicode.Get String(buf,
0, (int)memStream. Length));

Array.Clear(buf , 0, (int)memStream. Length);
memStream.Close ();
}

ICryptoTransfor m SetupCrypto()
{
TripleDESCrypto ServiceProvider des3 = new
TripleDESCrypto ServiceProvider ();

byte[] salt =
System.Text.UTF 8Encoding.UTF8. GetBytes("testK ey"); //Encryption key
SHA1 hash = new SHA1Managed();
for (int i = 0; i < 200; ++i)
{
salt = hash.ComputeHas h(salt, 0, salt.Length);
hash.Initialize ();
}
PasswordDeriveB ytes pdb = new
PasswordDeriveB ytes("testKey", salt, "SHA512", 1000);
Array.Clear(sal t, 0, salt.Length);
hash.Clear();

byte[] key3des = pdb.GetBytes(24 );
byte[] iv3des = pdb.GetBytes(8) ;

return( des3.CreateDecr yptor(key3des, iv3des) );
}
}
}

[Jon Skeet [C# MVP]]

SenseiHitokiri <se************ @gmail.comwrote :

hmm I swore I posted the code up in here but I don't see it. Well here
it is again. C#

<snip>

Well, the exception (after putting in a call to x.Program() - your
program as posted does nothing :) suggests that the data is invalid.
We'll need to see a short but complete program that produces that data
to start with, too.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

[SenseiHitokiri]

On Mar 20, 3:05 am, Jon Skeet [C# MVP] <[e-mail] wrote:

SenseiHitokiri <senseihitok... @gmail.comwrote :

hmm I swore I posted the code up in here but I don't see it. Well here
it is again. C#

<snip>

Well, the exception (after putting in a call to x.Program() - your
program as posted does nothing :) suggests that the data is invalid.
We'll need to see a short but complete program that produces that data
to start with, too.

--
Jon Skeet - <[e-mail] >http://www.pobox.com/~skeet Blog:http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

Hmm... that may be a little harder. I'm taking over this code from
someone else and at the moment that is in a seperate app that I do not
have access to. I can try to rip out the encrypt code from this
program and throw it up here but that may take me a bit to discern
it. Damn I wish he gave me some documentation lol.

[SenseiHitokiri]

Ok give this a whirl. It generates the encrypted string and prints it
to the screen but then gives me a bad data error when trying to
decrypt.

using System;
using System.Security .Cryptography;
using System.Text;
using System.IO;

namespace DebugCrypto
{
class DebugCrypto
{
ICryptoTransfor m enc3des, dec3des;
byte[] key3des = null;
byte[] iv3des = null;

static void Main(string[] args)
{
DebugCrypto x = new DebugCrypto();
string read = Console.ReadLin e();
while ( read != "exit" )
{
string encrypted = x.EncryptAndBas e64(read);

Console.WriteLi ne("Encrypting : ");
Console.WriteLi ne(encrypted);
Console.WriteLi ne("Decrypting : ");
Console.WriteLi ne(x.DecryptFro mBase64(encrypt ed));
Console.WriteLi ne("\n");
}
}

public DebugCrypto()
{
string sKey = "testKey";

TripleDESCrypto ServiceProvider des3 = new
TripleDESCrypto ServiceProvider ();

byte[] salt =
System.Text.UTF 8Encoding.UTF8. GetBytes(sKey);
SHA1 hash = new SHA1Managed();
for (int i = 0; i < 200; ++i)
{
salt = hash.ComputeHas h(salt, 0, salt.Length);
hash.Initialize ();
}
PasswordDeriveB ytes pdb = new PasswordDeriveB ytes(sKey,
salt, "SHA512", 1000);
Array.Clear(sal t, 0, salt.Length);
hash.Clear();

key3des = pdb.GetBytes(24 );
iv3des = pdb.GetBytes(8) ;

enc3des = des3.CreateEncr yptor(key3des, iv3des);
dec3des = des3.CreateDecr yptor(key3des, iv3des);
des3.Clear();
}

public string EncryptAndBase6 4(string val)
{
byte[] buf = UnicodeEncoding .Unicode.GetByt es(val);

MemoryStream memStream = new MemoryStream();
CryptoStream cryptStream = new CryptoStream(me mStream,
enc3des, CryptoStreamMod e.Write);

cryptStream.Wri te(buf, 0, buf.Length);
int memLength = (int)memStream. Length;

cryptStream.Flu shFinalBlock();
cryptStream.Cle ar();
Array.Clear(buf , 0, buf.Length);

buf = memStream.GetBu ffer();
val = Convert.ToBase6 4String(buf, 0, memLength );
Array.Clear(buf , 0, memLength );
return val;
}

public string DecryptFromBase 64(string base64str)
{
byte[] buf = Convert.FromBas e64String(base6 4str);
MemoryStream memStream = new MemoryStream();
CryptoStream cryptStream = new CryptoStream(me mStream,
dec3des, CryptoStreamMod e.Write);

cryptStream.Wri te(buf, 0, buf.Length);
int memLength = (int)memStream. Length;

cryptStream.Flu shFinalBlock();
cryptStream.Cle ar();
Array.Clear(buf , 0, buf.Length);
buf = memStream.GetBu ffer();

string ret = UnicodeEncoding .Unicode.GetStr ing(buf, 0,
memLength);
Array.Clear(buf , 0, memLength );
memStream.Close ();
return ret;
}
}
}

[Jon Skeet [C# MVP]]

SenseiHitokiri <se************ @gmail.comwrote :

Ok give this a whirl. It generates the encrypted string and prints it
to the screen but then gives me a bad data error when trying to
decrypt.

The encryption is broken:

public string EncryptAndBase6 4(string val)
{
byte[] buf = UnicodeEncoding .Unicode.GetByt es(val);

MemoryStream memStream = new MemoryStream();
CryptoStream cryptStream = new CryptoStream(me mStream,
enc3des, CryptoStreamMod e.Write);

cryptStream.Wri te(buf, 0, buf.Length);
int memLength = (int)memStream. Length;

cryptStream.Flu shFinalBlock();
cryptStream.Cle ar();
Array.Clear(buf , 0, buf.Length);

buf = memStream.GetBu ffer();
val = Convert.ToBase6 4String(buf, 0, memLength );
Array.Clear(buf , 0, memLength );
return val;
}

Note how it works out the length of memStream *before* it flushes the
final block. Just move that line to *after* cryptStream.Flu shFinalBlock
(and do the same in the decryption) and it works. However, it's not the
nicest way of doing it. It's simpler to use MemoryStream.To Array to get
the buffer, rather than asking for the length at all. I would
personally write the decryption code as (the encryption side mirrors
it, of course):

public string DecryptFromBase 64(string base64str)
{
byte[] buf = Convert.FromBas e64String(base6 4str);
using (MemoryStream memStream = new MemoryStream())
{
using (CryptoStream cryptStream = new CryptoStream
(memStream, dec3des, CryptoStreamMod e.Write))
{
cryptStream.Wri te(buf, 0, buf.Length);
// I don't think this is necessary in .NET 2.0
// but it is in 1.1 due to a bug in CryptoStream,
// IIRC
cryptStream.Flu shFinalBlock();
}

byte[] decrypted = memStream.ToArr ay();

return Encoding.Unicod e.GetString(dec rypted);
}
}

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too