[Mono-devel-list] Serialization of RSAParameters

[Christian Rudh]

Hi

Thanks for the explanation and the advice!
I got it to work using the .ToXmlString() now :)

/Christian

On Tue, 2003-10-21 at 23:18, Sebastien Pouliot wrote:
> Christian,
> 
> This is why it wont work:
> 
> 	[Serializable]
> 	public struct RSAParameters {
> 		[NonSerialized]
> 		public byte[] P;
> 		[NonSerialized]
> 		public byte[] Q;
> 		[NonSerialized]
> 		public byte[] D;
> 		[NonSerialized]
> 		public byte[] DP;
> 		[NonSerialized]
> 		public byte[] DQ;
> 		[NonSerialized]
> 		public byte[] InverseQ;
> 
> 		public byte[] Modulus;
> 		public byte[] Exponent;
> 	}
> 
> The private key is never serialized because it would introduce many security
> issues. This means that both signature and decryption are impossible using a
> serialized keypair.
> 
> This is also the case for MS framework
> (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html
> /frlrfsystemsecuritycryptographyrsaparametersclassdtopic.asp) so your sample
> shouldn't work under Windows.
> 
> The best way to get the full keypair is to use RSA.ToXmlString(true). This
> will give you an XML string containing the full keypair. You can then
> serialize with, of course, the proper security the resulting string.
> 
> Sebastien Pouliot
> Security Architect, Motus Technologies, http://www.motus.com
> work: spouliot at motus.com
> home: spouliot at videotron.ca
> blog: http://pages.infinit.net/ctech/poupou.html
> 
> 
> -----Original Message-----
> From: mono-devel-list-admin at lists.ximian.com
> [mailto:mono-devel-list-admin at lists.ximian.com]On Behalf Of Christian
> Rudh
> Sent: 21 octobre 2003 10:12
> To: mono-devel-list at lists.ximian.com
> Subject: [Mono-devel-list] Serialization of RSAParameters
> 
> 
> Hi
> 
> I am trying to serialize the RSA-keys into a bytestream so I can write
> them to disk (and a few other things). I'm able now to serialize them
> and then use it in encryption, but it doesn't work in decryption. I
> export to RSAParameters using the true-flag so I get everything, but
> when I deserialize it seems as if I only get the parts of the public key
> back? That's why encryption works fine, but not decryption.
> 
> I have compiled the following sources from various places and with my
> own code. It crashes when (in the end) it uses RSA2.decrypt. But if you
> comment out where it gets the RSAParameters from the deserialization
> (----2----) and instead import from the original RSA (-----1----) it
> works fine.
> 
> So are there any problems with serialization of RSAParameters or am I
> missing something?
> 
> 
> Regards,
> Christian Rudh
> 
> 
> //Create a UnicodeEncoder to convert between byte array and string.
> UnicodeEncoding ByteConverter = new UnicodeEncoding();
> 
> //Create byte arrays to hold original, encrypted, and decrypted data.
> byte[] dataToEncrypt = ByteConverter.GetBytes("Text to Encrypt");
> byte[] encryptedData;
> byte[] decryptedData;
> 
> //Create a new pair of keys
> RSACryptoServiceProvider RSA = new RSACryptoServiceProvider(1024);
> 
> //Export the public key
> RSAParameters RSAP = RSA.ExportParameters(true);
> 
> //Serialize the public key
> MemoryStream ms = new MemoryStream();
> BinaryFormatter b = new BinaryFormatter();
> b.Serialize(ms, RSAP);
> byte[] keyHolder = ms.ToArray();
> ms.Close();
> 
> //Deserialize the public key and store it in newRSAP
> MemoryStream ms2 = new MemoryStream(keyHolder);
> BinaryFormatter b2 = new BinaryFormatter();
> RSAParameters newRSAP = (RSAParameters)b2.Deserialize(ms2);
> ms2.Close();
> 
> //Encrypt the data using newRSAP which holds the RSAParameters
> RSACryptoServiceProvider RSA1 = new RSACryptoServiceProvider();
> RSA1.ImportParameters(newRSAP);
> encryptedData = RSA1.Encrypt(dataToEncrypt, false);
> 
> //Decrypt the data using newRSAP which holds the RSAParameters
> RSACryptoServiceProvider RSA2 = new RSACryptoServiceProvider();
> //-------------1-------------
> //RSA2.ImportParameters(RSA.ExportParameters(true));
> //-------------2-------------
> RSA2.ImportParameters(newRSAP);
> decryptedData = RSA2.Decrypt(encryptedData, false);
> 
> //Display the decrypted plaintext to the console.
> Console.WriteLine("Decrypted plaintext: {0}",
> ByteConverter.GetString(decryptedData));
> 
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