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I was recommended coSign for c# to sign and verify documents. I can't find anything helpful on the subject of using .cer and .pfx files to sign pdf files. I was assuming it would be as easy as loading a .cer file as a X509Certificate2, and then coSign could just import it.

Samples for coSign seem limited. I was able to get coSign to verify if a document had a signature already on it, but I have no idea if it can verify if that is the same one based on the digital certificate.

I've also used another library to sign documents with those type of certificate files. It is not able to verify digital signatures though.

lockgar
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2 Answers2

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With CoSign you can import externally-issued certificates and keys to your CoSign account. However, it is important to note that typically every CoSign account (whether CoSign on-premise or CoSign Cloud) by default already includes a key and a certificate that can be used for signing.

If you do want to use a different signature key and certificate issued on a PFX file, for example, you can follow the procedure below:

  • From a command-line run the utility C:\Program Files\ARX\ARX CryptoKit\utils\pkcs12util.exe You will need to specify the PFX filename and PFX file password

  • Your CoSign account should now include the key and certificate from the PFX file and you can use CoSign SAPI for signing with it.

Ari S.
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When you create a CoSign Trial or Cloud account the certificate is created on the CoSign Appliance for you. You cannot import your own certificate to the appliance, nor do you need to.

The API calls should be made to the CoSign appliance in order to function, at no time can signatures be made if the CoSign appliance is not being used (otherwise it wouldn't be so secure). You will notice that even with your CoSign user certificate that you cannot export a PFX or P12 file, because you can never export the private key from the appliance.

Regards,

Dave Strang

The Digital Signature Company Phone: (866) 327-9754 Email: daves@arx.com Website: www.arx.com

user3546821
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