How to Retrieve a C# Digital Signature

A digital signature lets your email recipients verify that an email came from you. You can add a digital signature to an email, which helps fight against phishing emails and identity theft. When you automate emails with C#, you must grab the digital signal and verify that it is up to date. This is all automated using C# classes and functions available in the Visual Studio software that hosts C# programming tools.

Things You'll Need

• Visual Studio

Instructions

1. Click the Windows "Start" button and "All Programs." Click the "Microsoft .NET Framework" program group, then click "Visual Studio." Your software opens.

2. Click the icon labeled "Open." Double-click your project file name to open your C# code. The code file that opens is where you type the digital signature retrieval code.

3. Type the following code to retrieve the digital signature from the user's certificate store:

   X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser);

   my.Open(OpenFlags.ReadOnly);

4. Get the user key. The key is the pass code for the digital signature. Type the following line of code to retrieve the key from the key store on the server, which houses all digital signatures for your network:

   csp = (RSACryptoServiceProvider)certificate.PrivateKey;

5. Verify that the digital signature is good, meaning it has not expired and is a valid key. Type the following line of code to verify that the signature is not corrupted or expired:

   return csp.VerifyHash(hash, CryptoConfig.MapNameToOID("SHA1"), signature);

References

• Fyan's Digital World: C# - How to Sign and Verify Digital Signatures