Re: .Net & Java - RSA Encryption/Decryption Problem.
From: Valery Pryamikov (Valery_at_nospam.harper.no)
Date: 09/28/04
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Date: Tue, 28 Sep 2004 19:15:33 +0200
Have you checked that link on Mitch's site:
http://www.jensign.com/JavaScience/dotnet/RSAEncrypt/index.html
-Valery.
http://www.harper.no/valery
"Ali Khawaja" <alikha@gmail.com> wrote in message
news:f99ae6b7.0409280908.c3aed8a@posting.google.com...
>I am encrypting some text using java bouncyCastle RSA provider, and
> trying to decrypt using .Net.
>
> I was given a pfx file. I installed it in my system's certificate
> store. Then I exported the public key in an x509 certificate, used
> that in my java code to encrypt the data and write it to a file as
> follows:
> ----------------------------------------
> InputStream inStream = getClass().getResourceAsStream("pubkey.cer");
> CertificateFactory cf = CertificateFactory.getInstance("X.509");
> cert = (X509Certificate)cf.generateCertificate(inStream);
>
> String info = "Hello how are you"; // string to encode
> Cipher rsaCipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", "BC");
> rsaCipher.init(Cipher.ENCRYPT_MODE, cert);
> byte[] encryptedData = rsaCipher.doFinal(info.getBytes());
>
> FileOutputStream fos = new FileOutputStream(encfilePath,false);
> fos.write(encryptedData);
> fos.close();
> ------------------------------------------
> If I print the public key from java code after creating the
> certificate, its same as the public key of the certificate in my
> system's certificate store.
>
> After writing the encyrpted data to a file, I try to open the file and
> decrypt using the certificate. I have tried three different ways.
>
> -----CAPICOM -----------
> First, I tried CAPICOM, and it said "ASN1 bad tag value met."
>
> CAPICOM.EnvelopedData env = new CAPICOM.EnvelopedDataClass();
> Certificate cert = GetCAPICertificate();
> env.Recipients.Add(cert);
> env.Decrypt(txtEncryptedData.Text);
>
> GetCAPICertificate is my method that gets the Certificate from system
> certificate store. i have made sure that the certificate is the
> correct one.
>
> I opened the encoded file in asndump utitlity and it did not complain
> about anything. Following is the output:
>
> File: H:\Documents and Settings\Ali\.coltencrypted
> Time: 11:51:41, 09/28/2004
> ---------------------------------------------------------------------
> <51 0F>
> [APPLICATION 17]
> 07 93 A2 EF 30 74 39 81 ....0t9.
> 77 9C AD F3 DE B7 DA w......
>
> ---------------------------------------------------------------------
>
> Second thing I tried was to use Security Guru Mitch Gallant's pfxopen
> utility, that allows you to load a pfx file in a keycontainer, and
> initialize RSA using CSP that is initialized by that keycontainer. It
> throws an exception saying:
>
> Bad Data at
> System.Security.Cryptography.RSACryptoServiceProvider._DecryptPKWin2KEnh
> .. System.Security.Cryptography.RSACryptoServiceProvider .....
> at CertTestApp.CryptoForm.DecryptUsingPfx() in
> h:\projects\colt\certtestapp\form1.cs:line 311
>
> Here's the code:
>
> string pfxfilename = @"H:\Projects\Colt\cert\ColtPOSCert_0924.pfx";
> string pwd = string.Empty;
> PfxOpen pfx = new PfxOpen();
> pfx.LoadPfx(pfxfilename,ref pwd);
>
> CspParameters csp = new CspParameters();
> csp.KeyContainerName = pfx.container;
> csp.KeyNumber = 1;
>
> Stream stream = new FileStream(@"H:\Documents and
> Settings\Ali\.coltencrypted",FileMode.Open);
> int datalen = (int)stream.Length;
> byte[] filebytes = new byte[datalen];
> stream.Seek(0,SeekOrigin.Begin);
> stream.Read(filebytes,0,datalen);
> stream.Close();
>
> RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(csp);
> byte[] decryptedData = rsa.Decrypt(filebytes,false);
> ------------------------------------------------------------------
>
> Finally I tried WSE 2.0: I probed the certifcates in the system
> certifcate store, and got the certificate that i needed to decrypt. it
> has a very nice method on the certificate to export the parameters
> including the private ones in a CSPParameters object, after which you
> can import them in the RSACryptoServiceProvider. That failed also
> *sigh*, saying that
>
> Export of private parameters is not supported
> at
> Microsoft.Web.Services2.Security.Cryptography.RSACryptoServiceProvider.ExportParameters(Boolean
> includePrivateParameters)
>
> My code was:
>
> RSAParameters coltParams = certificate.Key.ExportParameters(true);
> RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
> rsa.ImportParameters(coltParams);
>
> It just failed at the very first line saying export of private
> parameters is not supported. Tooltip on the method says that "When
> overriden in a derived class, exports the RSA parameters ...".
>
> ------------------------------------------------
>
> So i am kinda stuck. i am not too good with security, but i am
> obviously missing something. sorry for the long post, but i'll really
> appreciate any help.
>
> Thanks
> Ali
> alikha@gmail.com
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