Protect CAD Documents

With Autodesk products, there are two methods used for protecting a drawing. Digital Certificate or Password Protect you document. We will give you a short description of each and describe how a Hash Code can help determine if a drawing is valid.

Digital Certificates

You may purchase a standard (Person Not Validated) Certificate from Verisign for $20USD. This validates the user by email only. Other more strict certificates will call and verify the business information. Once you have downloaded a certificate, it will have a Private Key that you will choose when creating the certificate. To install this certificate with a Private Key (PK), you will be prompted to enter it to install on your local machine. If you only need the Public Certificate (Without PK), you can export this with Internet Explorer, under Certificates. You may distribute the Public Key to any user along with your CAD file that has been signed with your installed PK Certificate. If you do not send the Public Key Certificate for the user to install, they will not see the drawing is Valid Signature Dialog Box.

To use a Digital Certificate, do the following steps:

1. Purchase a Digital Certificate; You will create a PK, which is stored inside the Certificate.

2. Install the Digital Certificate on your local machine for strong PK signing of CAD drawings.

3 Either you the Autodesk Certificate dialog under “Security Options” or use AEC Signature to sign your drawing.

4. Distribute your Public Key Certificate (Must be Exported. ). This does not have a Password attached, so the user can click to install.

As a result, the end user can’t change the certificate on the drawing, but will be notified if they change it on their end.

Password Protect

Under Security Options in AutoCAD, select Password Protect Document, and enter your password. This will force the user to enter a password to open the drawing. Note, you CANNOT use Certificates and Password Protect at the same time. It’s either or! With AEC Signature, you can password protect the document and generate a report.

Hash Code

Hashes, Checksums or Cyclic Redundancy Checks (CRC) are used on CLOSED files with read access to generate a hash code to compare with the original file to determine if there have been any changes. If the codes are not equal, then the file has changed. AEC Signature uses the following hash algorithms: MD5, SHA1, SHA256, SHA384, SHA512.

If you have an open CAD file, the file access is partially locked, so hash software cannot complete the read. That is why we write out a copy of your drawing in AEC Signature. We can then perform a read to generate a public key report.


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