If you want to integrate PKCS7 signing/verifying with a browser and it's not a problem that it's only Internet Explorer (or Netscape + ActiveX plugin) you can look at Capicom. It's a free component and available at the MSDN website.
If you want to integrate PKCS7 signing/verifying with a browser and it's not a problem that it's only Internet Explorer (or Netscape + ActiveX plugin) you can look at Capicom. It's a free component and available at the MSDN website.