A digital signature is the mechanism for indicating one's approval of DGN files to other users and communicating approval in a verifiable manner. A digital signature captures the current state of a model or file.

Background

A digital signature (not to be confused with a digital certificate) is an electronic signature that can be used to authenticate the identity of the sender of a message or the signer of a document, and possibly to ensure that the original content of the message or document that has been sent is unchanged. 

Digitally signing a model or file can be used to indicate approval of the design. Another user can then detect the signature, verify the signer´s identity, and verify that the design has not been changed since it was signed. Model-specific signatures are displayed graphically in the context of the design. Multiple signatures can be affixed to a single file or model. Hierarchical signing is also supported so that one signature is dependent upon prior signatures. A signature can cover the content of a model or file and all of its references including DGN and DWG references.

Steps to Accomplish

Option 1 Adding File Signature(You must have certificate for dignature signature installed)

1. You must go to Workspace>Configuration>Protection and enable protection
2. Go to Tools>Security>Digital>Open Toolbox
3. Click on Add File Signature.
4. Click on Browse button, this will open to location of where personal certificate store has the file stored on your machine
5. (Optional) Enter the reason the file is being signed in the Purpose field.
6. (Optional) Enter the date the signature expires in the Expiry field.
7. (Optional) Click the Include References check box if you want the contents of all references attached to the master file to be included in the signature.
8. Select certificate, Click OK. The new signature is annotated automatically with the current time from the
   signer´s machine.

Option 2 Using a digital signature cell

A signature cell is really just a cell. It is created and managed as a normal cell in a cell library. It is then placed in the model that is being signed. What makes a signature cell special is that it itself is digitally signed

1. Click the Attach Signature Cell Library icon
2. Select the signature cell.
3. Select the signature cell from the Cell drop-down list. Only valid signature cells belonging to the current view are displayed and available for placement.
4. Place a data point in the DGN being signed.

Option 3 Adding a Model Signature

The Place Signature Cell tool is used to place a model signature that applies to and is displayed in the context of the current model. A model signature requires a signature cell that is placed in the current model to represent the signature visually.  A model signature applies to the contents of the current model

1. From the Digital Signatures dialog, select the Place Signature Cell icon. This tool is used to place a model signature that applies to and displays in the current model.
2. Select the cell library that contains the signature cell with the Attach Signature Cell Library tool. The Cell field will be populated with a list of available signature cells from the currently attached signature cell library.
3. Choose a signature cell from the Cell pull-down menu.
4. Enter the angle and scale of the cell.
5. (Optional) Check the Include Reference box to include all attached references in the signing.
6. (Optional) Enter the name of the person signing the model in the Signer field. The Signer defaults to the current user´s login name.
7. (Optional) Enter a description of the signer´s intent.
8. (Optional) Enter a date that the signature expires.
9. Check this option to make the new signature depend on all signatures that are currently selected in the Digital Signatures dialog. This check box is disabled if no signatures are selected.
10. Click a data point to place the signature cell. The new signature displays in the current model of the DGN file and appears in the Signature dialog.

A red seal next to the signature in the model indicates that it is a signature. Moving or modifying the signature invalidates the signature. An invalid signature is displayed with a red X across it. A yellow warning symbol is displayed if the signature is based on a certificate that is not trusted or if the signature has expired.

Use the Add Signature tool on the Digital Signatures dialog to add additional signatures to a file or model. Adding a new signature does not invalidate existing signatures. The same user can place multiple instances of the same signature cell or multiple signature cells. The same user can also place a mixture of file, model, and hidden model signatures.

Creating a Signing Hierarchy

 To create a hierarchy, the signer selects one or more existing signatures in the Digital Signatures dialog before activating the Add Model or File Signature tool. The signer then specifies that the new signature will depend on the selected signatures.

1. From the Digital Signatures dialog, select one or more existing signatures.
2. Select the Add File Signature (or Place Signature Cell) icon. The Add File Signature (or Place Signature Cell) dialog opens. The name of the signer and there location is filled in from the selection of the certificate.
3. Select a certificate from your personal certificate store.
4. Click the Dependent Signature check box if you want to create a signature hierarchy.
5. Click OK.

See Also

Digital Signatures - Security - Microstation

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