signature with SHA256

问题:

I have a smartcard and I need to sign a file with this. That is a big problem as I see in stackover.

I couldnt use RSACryptoServiceProvider, bkz it doesnt support RSA-SHA256 alogrithm.

At First I used CAPICOM.dll , like code bellow,

SignedData sed = new SignedData(); sed.Content = "a"; // data to sign Signer ser = new Signer(); ser.Certificate = cc; string singnn = sed.Sign(ser, false, CAPICOM_ENCODING_TYPE.CAPICOM_ENCODE_BASE64); 

But there isnt a public key to validate my signature value,, I couldnt get a validate key from capicom.dll.

And after ,

I used X509Certificate2 , and RSACryptoServiceProvider like code below,

        X509Certificate2 certificate = new X509Certificate2();         // Access Personal (MY) certificate store of current user         X509Store my = new X509Store(StoreName.My, StoreLocation.CurrentUser);         my.Open(OpenFlags.ReadOnly);          // Find the certificate we'll use to sign                     RSACryptoServiceProvider csp = null;         foreach (X509Certificate2 cert in my.Certificates)         {             if (cert.Subject.Contains(certSubject))             {                 // We found it.                  // Get its associated CSP and private key                 certificate = cert;                 csp = (RSACryptoServiceProvider)cert.PrivateKey;             }         }         if (csp == null)         {             throw new Exception("No valid cert was found");         }          // Hash the data         SHA1Managed sha1 = new SHA1Managed();         UnicodeEncoding encoding = new UnicodeEncoding();         byte[] data = encoding.GetBytes(text);         byte[] hash = sha1.ComputeHash(data);          //byte[] data = Encoding.UTF8.GetBytes(text);         //HashAlgorithm sha = new SHA256Managed();         //byte[] hash = sha.TransformFinalBlock(data, 0, data.Length);          string key = csp.ToXmlString(false);         // Sign the hash         csp.PersistKeyInCsp = true;         byte[] response = csp.SignData(data, CryptoConfig.MapNameToOID("SHA1"));         string signbase64 = Convert.ToBase64String(response); 

It works , but I need to sign with RSA-SHA256 algorithm. When I changw hash algorithm like this

byte[] response = csp.SignData(data, CryptoConfig.MapNameToOID("SHA256")); 

I m getting an

error : "unspecified error".

Thats my problem, What is the sollution , or which library should I use ??

Thanks for any advice..

回答1:

RSACryptoServiceProvider does work with SHA2-based signatures, but you have to invest some effort into it.

When you use a certificate to get your RSACryptoServiceProvider it really matters what's the underlying CryptoAPI provider. By default, when you create a certificate with 'makecert', it's "RSA-FULL" which only supports SHA1 hashes for signature. You need the new "RSA-AES" one that supports SHA2.

So, you can create your certificate with an additional option: -sp "Microsoft Enhanced RSA and AES Cryptographic Provider" (or an equivalent -sy 24) and then your code would look like (in .NET 4.0):

var rsa = signerCertificate.PrivateKey as RSACryptoServiceProvider; // byte[] signature = rsa.SignData(data, CryptoConfig.CreateFromName("SHA256")); 

If you are unable to change the way your certificate is issued, there is a semi-ligitimate workaround that is based on the fact that by default RSACryptoServiceProvider is created with support for SHA2. So, the following code would also work, but it is a bit uglier: (what this code does is it creates a new RSACryptoServiceProvider and imports the keys from the one we got from the certificate)

var rsa = signerCertificate.PrivateKey as RSACryptoServiceProvider; // Create a new RSACryptoServiceProvider RSACryptoServiceProvider rsaClear = new RSACryptoServiceProvider(); // Export RSA parameters from 'rsa' and import them into 'rsaClear' rsaClear.ImportParameters(rsa.ExportParameters(true)); byte[] signature = rsaClear.SignData(data, CryptoConfig.CreateFromName("SHA256")); 

Hope you find this helpful.

文章来源: signature with SHA256