Sign a document by SmartCard on the .NET client and verify on the SQL 2005 server

Hi!
I'm working on the following application:

In the client application (written in C#) an user signs a document by private key, stored on chip card. Signed document and the signature are stored into database on SQL 2005 server.
There is my client code for demonstration:

Client application sample:

System.Data.SqlClient.SqlConnection conn =new System.Data.SqlClient.SqlConnection("Data Source=localhost;Initial Catalog=Test;Integrated Security=True"); conn.Open(); try { CspParameters csp =new CspParameters(1, "Schlumberger Cryptographic Service Provider"); csp.KeyNumber=1; // Initialize an RSACryptoServiceProvider object using // the CspParameters object. RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(csp); // Create some data to sign. string text = "plain text to sign"; // Sign the data using the Smart Card CryptoGraphic Provider. byte[] sig = rsa.SignData(Encoding.Unicode.GetBytes(text), "SHA1"); Console.WriteLine("Signature:\t" + BitConverter.ToString(sig)); // Write to db SqlCommand cmd = new SqlCommand("insert into signed (data, sign) values (@data, @sign) ", conn); SqlParameter parData = new SqlParameter("@data", text); cmd.Parameters.Add(parData); SqlParameter parSign = new SqlParameter("@sign", sig); cmd.Parameters.Add(parSign); cmd.ExecuteNonQuery(); // Verify the data using the Smart Card CryptoGraphic Provider. bool verified = rsa.VerifyData(Encoding.Unicode.GetBytes(text), "SHA1", sig); Console.WriteLine("Verified:\t" + verified); } finally { conn.Close(); }

The document and the signature are stored into the Signed table in the Test database:

use [Test] CREATETABLE [dbo].[signed]( [id] [int]IDENTITY(1,1)NOTNULL, [data] [nvarchar](50)COLLATE Czech_CI_ASNULL, [sign] [varbinary](max)NULL, CONSTRAINT [PK_signed]PRIMARYKEYCLUSTERED )ON [PRIMARY]

Now I want check signature validity on server side.
I found the certificate stored on my chip card in certificate store Current User/Personal/Certificates (the Certificates MMC snapin). I exported it into the binary DER encoded file (cer extension).
Then I imported this certificate into the database [Test] using CREATE CERTIFICATE statement:

CREATECERTIFICATE testCert FROMFILE='c:\temp\My Test Certificate.cer'

Now, I want to verify signature by theVerifySignedByCert() statement:

select VerifySignedByCert( Cert_ID('testCert'), data, [sign])as verifiedFROM signed

The VerifySignedByCert returns 0. I don't understand WHY?
WHAT'S WRONG?

Please help me!

Thankyou
Fipil.

[9829 byte] By [Fipil] at [2008-2-25]