"Steven Cheng[MSFT]" wrote:

> Hello Benny,
>
> From your description, you're going to use the DSA provider component in
> .net framework to perform digital signing on message, and you're wondering
> how to supply the private key for the provider ,correct?
>
> Based on my experience, priviate key for digtal signing are contained in
> CSP Containers. Generally, when you get a certificate(for encrypting and
> signing), you will get public/private key pair. And you can specify a
> container name when requesting the certificate from CA. After the
> certificate is installed on your computer(in user or computer store), you
> can get the private key either from the certificate(if private key is not
> exported) or from the CSP container(if you've specify a container name or
> know an existing key container).  Then, in .net code, you can either
> retrieve a DSA Provider from the certificate's PrivateKey property  or use
> CspParameters(specify key container name and providertype ) to create a DSA
> Provider. Here are two code snippet demonstrate this:
>
> =======get DSA provider from certificate======
>  private void btnSign_Click(object sender, EventArgs e)
>         {
>             string tp;
>
> //Thumbprint of the certificate
>             tp = "90 6e 56 71 da 31 ac bc 9e 3e 8b b2 08 5f 6e a9 ec f1 21
> 7a";
>
>             X509Store store = new X509Store(StoreName.My,
> StoreLocation.CurrentUser);
>             store.Open(OpenFlags.ReadOnly);
>
>             X509Certificate2Collection certs = 
> store.Certificates.Find(X509FindType.FindByThumbprint, tp, false);
>
>           
>             X509Certificate2 dsauser = certs[0];
>
>             store.Close();
>
>            
>             DSACryptoServiceProvider dsa = dsauser.PrivateKey as
> DSACryptoServiceProvider;
>
>          
>
>             if (dsa != null)
>             {
>                 string plaintext = "123456";
>
>                 byte[] hashedtext =
> SHA1.Create().ComputeHash(Encoding.UTF8.GetBytes(plaintext));
>
>                 byte[] signature = dsa.CreateSignature(hashedtext);
>
>                 MessageBox.Show("signature: " +
> Convert.ToBase64String(signature));
>
>
>                 MessageBox.Show("Signature Isvalid: " + 
> dsa.VerifySignature(hashedtext, signature));
>
>            
>             
>             }
>         }
> =============================
>
> =====create DSA provider from key container==============
>         private void btnSignCSP_Click(object sender, EventArgs e)
>         {
>
>             CspParameters csp = new CspParameters();
>
>
>             csp.KeyContainerName = "SC-TEST-CERT2";
>
>    
>             //csp.ProviderName = "Microsoft Enhanced DSS and Diffie-Hellman
> Cryptographic Provider";
>
>             csp.ProviderType = 13;
>
>             DSACryptoServiceProvider dsa = new
> DSACryptoServiceProvider(csp) ;// dsauser.PrivateKey as
> DSACryptoServiceProvider;
>
>             if (dsa != null)
>             {
>                 string plaintext = "123456";
>                 byte[] hashedtext =
> SHA1.Create().ComputeHash(Encoding.UTF8.GetBytes(plaintext));
>
>                 byte[] signature = dsa.CreateSignature(hashedtext);
>
>                 MessageBox.Show("signature: " +
> Convert.ToBase64String(signature));
>
>
>                 MessageBox.Show("Signature Isvalid: " +
> dsa.VerifySignature(hashedtext, signature));
>
>             }
>
>         }
>     }
> =================================
>
> For test, you can setup a CA on windows server machine to issue some test
> certificate(make sure you choose the DSS provider).  Here are two good web
> articles introducing the cryptography programming in .net framework:
>
>
> #Cryptography in Microsoft.NET Part I: Encryption
> http://www.c-sharpcorner.com/UploadFile/gsparamasivam/CryptEncryption1128200
> 5061028AM/CryptEncryption.aspx
>
> #Cryptography in Microsoft.NET Part II: Digital Envelop and Digital
> Signatures
> http://www.c-sharpcorner.com/UploadFile/Gowri%20S%20Paramasivam/Cryptography
> 211242005003308AM/Cryptography2.aspx?ArticleID=cf900b08-35ed-4524-aeff-68062
> 65a4196
>
>
> Hope this helps.
>
> Sincerely,
>
> Steven Cheng
>
> Microsoft MSDN Online Support Lead
>
> 
>
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