Using cryptographic streams with XML

[theinsanecoder@gmail.com]

Hi, i'm using the xmlserializer to load and unload data from my files
but i want to crypt them using a not so secure cryptographic encoder.
My code to encrypt "seems" to work fine, the file is outputted but when
i import the file again using the same concept (but in reversed form) i
get XMLDocument is invalid (1, 1) exception thrown back at me. Here is
the code :

SAVING PORTION

'Save the game
Dim oXS As XmlSerializer = New
XmlSerializer(G etType(Game.Gam e))
Dim oStmW As StreamWriter
Dim oXmlW As XmlTextWriter

'Setup the stream writer
oStmW = New StreamWriter(pF ilename)

'Setup cryptographic stream cypher
Dim CryptoAlgo As New DESCryptoServic eProvider()
Dim Cryptographer As
System.Security .Cryptography.C ryptoStream
CryptoAlgo.Bloc kSize = 64
CryptoAlgo.KeyS ize = 64
Cryptographer = New
System.Security .Cryptography.C ryptoStream(oSt mW.BaseStream,
CryptoAlgo.Crea teEncryptor(KEY _8, IV_8), CryptoStreamMod e.Write)

'Setup the text writer with cryptostream instead of
original stream (Crypto will link them)
oXmlW = New XmlTextWriter(C ryptographer, New
System.Text.UTF 8Encoding())

'Execute the write
oXS.Serialize(o XmlW, Game)
oXmlW.Close()



LOADING PORTION

'Load the new game
Dim oXS As XmlSerializer = New
XmlSerializer(G etType(Game.Gam e))
Dim oStmR As StreamReader
Dim oXmlR As XmlTextReader

'Setup the stream reader
oStmR = New StreamReader(pF ilename)

'Setup cryptographic stream cypher
Dim CryptoAlgo As New DESCryptoServic eProvider()
Dim Cryptographer As
System.Security .Cryptography.C ryptoStream
CryptoAlgo.Bloc kSize = 64
CryptoAlgo.KeyS ize = 64
Cryptographer = New
System.Security .Cryptography.C ryptoStream(oSt mR.BaseStream,
CryptoAlgo.Crea teEncryptor(KEY _8, IV_8), CryptoStreamMod e.Read)

'Setup the text reader with cryptostream instead of
original stream (Crypto will link them)
oXmlR = New XmlTextReader(C ryptographer)

'Execute the read
oXmlR.Whitespac eHandling =
WhitespaceHandl ing.Significant
Game = oXS.Deserialize (oXmlR)
oXmlR.Close()

Like said earlier, SAVING seems to work fine and outputs a file that is
encrypted when i open it from notepad, but i may be wrong, maybe it's
just outputting rubish. The Load definitely doesn't work throwing back
an InvalidOperatio nException with the following content, "There is an
error in the XML document (1, 1)"

Can anyone help please?

[tomb]

Re: Using cryptographic streams with XML

Try not using the xmlwriter for the encrypted output. Just use the
xmlreader for the unencrypted input. Mind you, I'm no expert on xml nor
cryptography, but purely from a logical perspective, the . It's worth a
shot.

Tom

theinsanecoder@ gmail.com wrote:

>Hi, i'm using the xmlserializer to load and unload data from my files
>but i want to crypt them using a not so secure cryptographic encoder.
>My code to encrypt "seems" to work fine, the file is outputted but when
>i import the file again using the same concept (but in reversed form) i
>get XMLDocument is invalid (1, 1) exception thrown back at me. Here is
>the code :
>
>SAVING PORTION
>
'Save the game
Dim oXS As XmlSerializer = New
>XmlSerializer( GetType(Game.Ga me))
Dim oStmW As StreamWriter
Dim oXmlW As XmlTextWriter
>
'Setup the stream writer
oStmW = New StreamWriter(pF ilename)
>
'Setup cryptographic stream cypher
Dim CryptoAlgo As New DESCryptoServic eProvider()
Dim Cryptographer As
>System.Securit y.Cryptography. CryptoStream
CryptoAlgo.Bloc kSize = 64
CryptoAlgo.KeyS ize = 64
Cryptographer = New
>System.Securit y.Cryptography. CryptoStream(oS tmW.BaseStream,
>CryptoAlgo.Cre ateEncryptor(KE Y_8, IV_8), CryptoStreamMod e.Write)
>
'Setup the text writer with cryptostream instead of
>original stream (Crypto will link them)
oXmlW = New XmlTextWriter(C ryptographer, New
>System.Text.UT F8Encoding())
>
'Execute the write
oXS.Serialize(o XmlW, Game)
oXmlW.Close()
>
>
>
>LOADING PORTION
>
'Load the new game
Dim oXS As XmlSerializer = New
>XmlSerializer( GetType(Game.Ga me))
Dim oStmR As StreamReader
Dim oXmlR As XmlTextReader
>
'Setup the stream reader
oStmR = New StreamReader(pF ilename)
>
'Setup cryptographic stream cypher
Dim CryptoAlgo As New DESCryptoServic eProvider()
Dim Cryptographer As
>System.Securit y.Cryptography. CryptoStream
CryptoAlgo.Bloc kSize = 64
CryptoAlgo.KeyS ize = 64
Cryptographer = New
>System.Securit y.Cryptography. CryptoStream(oS tmR.BaseStream,
>CryptoAlgo.Cre ateEncryptor(KE Y_8, IV_8), CryptoStreamMod e.Read)
>
'Setup the text reader with cryptostream instead of
>original stream (Crypto will link them)
oXmlR = New XmlTextReader(C ryptographer)
>
'Execute the read
oXmlR.Whitespac eHandling =
>WhitespaceHand ling.Significan t
Game = oXS.Deserialize (oXmlR)
oXmlR.Close()
>
>Like said earlier, SAVING seems to work fine and outputs a file that is
>encrypted when i open it from notepad, but i may be wrong, maybe it's
>just outputting rubish. The Load definitely doesn't work throwing back
>an InvalidOperatio nException with the following content, "There is an
>error in the XML document (1, 1)"
>
>Can anyone help please?
>
>
>

[crazyone]

Re: Using cryptographic streams with XML

Problem is if i don't use an XML reader or XML Writer i can't keep the
line feeds in my descriptive texts. I'd have to provide some complex
HTML content which would output <BR>s insteads of vbCrLfs... Unless you
klnow of a solution to bypass the line feeding problem i have to keep
the text reader/writer...