signformat

Records the type of encoding that a form viewing program must use to create the mimedata setting in a signature. Specifically, the parameters in signformat specify:

About the mimedata setting:

To create the mimedata setting, a form viewer takes the signer's certificate and a plaintext representation of the form or portion of the form that the signature applies to, and encodes them according to the settings in signformat. For details, see the mimedata option.

Syntax

   <signformat>MIME type; 
      engine="signature engine";
      verifier;
      cval;
      delete;
      parameters
      layoutoverlaptest
   </signformat>
Table 1. signformat properties
Parameter Type Description
MIMEtype string the MIME type of the signed data. May be:
  • XFDL – application/vnd.xfdl
signature engine string the type of signature. Valid types are:
  • ClickWrap
  • CryptoAPI
  • Entrust
  • Generic RSA (includes CryptoAPI and Netscape)
  • HMAC-ClickWrap
  • Netscape
  • signaturePad
  • Silanis

Default: Generic RSA
verifier string an optional flag that indicates which verifier should be used when verifying certificate chains during digital signature operations. Valid verifiers are:
  • Basic – Performs basic certificate verification.
  • DODJ12 – Performs strict certificate verification that complies with US Department of Defense requirements.

Default: Basic
cval string an optional flag that indicates whether the current value of computed options is signed. This is useful if you want to sign the compute, but not the value calculated by the compute (for example, if you are signing the presentation layer of a form).

If you want to sign the current values, do not use this flag. If you do not want to sign the current values, use: cval="off"

Default: current values are signed.
delete string an optional flag that indicates whether the signature can be deleted by the user. By default, all signatures can be deleted. If you want to prevent a signature from being deleted, use: delete="off"
parameters depends on engine additional parameters required by the signature engine (see the following)
layoutoverlaptest string an optional flag that can be set to perform the layout and overlap test. Values can be:
  • required – The layout and overlap test must be performed for any signature type and must be verified. If the signature type does not support the layout and overlap test an error message is presented to the user.
  • optional – The layout and overlap test must be performed if available, and must be verified if possible.
  • none – The layout and overlap test is not performed.

The default value is optional for all signature engines except ClickWrap. The ClickWrap default is none.

Available In

button, signature

About the signature Engines

The following table describes the signature engines that are available:

Table 2. available signature engines
signature Engine Description
ClickWrap The ClickWrap signature allows users to sign a form without requiring a digital certificate. Instead, signers may have to answer some questions about themselves and echo some text to indicate their intent to agree to the document.
CryptoAPI The CryptoAPI signature uses digital certificates that are stored in your Internet Explorer certificate store to create a digital signature.
Entrust The Entrust signature allows the end-user to sign the form using the Entrust brand of products.
Generic RSA The Generic RSA signature uses digital certificates from either your Internet Explorer or your Netscape certificate store.
HMAC-ClickWrap The HMAC-ClickWrap signature is similar to the ClickWrap signature, in that the end-user does not require a digital certificate to create a signature. Instead, the end-user provides a shared secret (such as a password) that can be verified by a server. Once the signature is verified, the server then uses its own digital certificate to sign the form and validate the end-user's non-digital signature.
Netscape The Netscape signature uses digital certificates that are stored in your Netscape certificate store to create a digital signature.
signaturePad The signaturePad signature allows the end-user to sign the form using a variety of pad-style hardware. This signature type includes support for signature pads from Interlink and Topaz, as well as pads that support the WinTab standard.
Silanis A Silanis signature allows the end-user to sign the form using the Silanis brand of products. It is also the only signature type that can create non-locking signatures, in which the data that is signed is not locked to prevent changes.

Additional Parameters for Common signature Engines

The following table details the additional parameters you must use for each signature type when defining the signformat option. Note that the Generic RSA signature does not require any additional parameters.

Table 3. additional parameters for signature engines.
signature engine examples
Engine Parameter Valid Settings Description
Clickwrap, HMAC-Clickwrap hashalg sha1 hash algorithm with 160-bit message digest. This is the default setting.
Clickwrap, HMAC-Clickwrap hashalg sha256 hash algorithm with 256-bit message digest
Clickwrap, HMAC-Clickwrap hashalg sha384 hash algorithm with 384-bit message digest
Clickwrap, HMAC-Clickwrap hashalg sha512 hash algorithm with 512-bit message digest
Clickwrap, HMAC-Clickwrap hashalg md5 hash algorithm with 128-bit message digest
Clickwrap, HMAC-Clickwrap titleText String text to display for the main title of the signature dialog box
Clickwrap, HMAC-Clickwrap mainPrompt String text to display for the main prompt
Clickwrap, HMAC-Clickwrap mainText String text to display for the main text
Clickwrap, HMAC-Clickwrap question1Text String label for the first question
Clickwrap, HMAC-Clickwrap answer1Text String default answer to the first question; user can overwrite
Clickwrap, HMAC-Clickwrap question2Text String label for the second question
Clickwrap, HMAC-Clickwrap answer2Text String default answer to the second question; user can overwrite
Clickwrap, HMAC-Clickwrap question3Text String label for the third question
Clickwrap, HMAC-Clickwrap answer3Text String default answer to the third question; user can overwrite
Clickwrap, HMAC-Clickwrap question4Text String label for the forth question
Clickwrap, HMAC-Clickwrap answer4Text String default answer to the forth question; user can overwrite
Clickwrap, HMAC-Clickwrap question5Text String label for the fifth question
Clickwrap, HMAC-Clickwrap answer5Text String default answer to the fifth question; user can overwrite
Clickwrap, HMAC-Clickwrap echoPrompt String text to display for the echo prompt
Clickwrap, HMAC-Clickwrap echoText String text the user enters. For example, the actual echo text typed by the user
Clickwrap, HMAC-Clickwrap buttonPrompt String text to display before the accept and reject buttons
Clickwrap, HMAC-Clickwrap acceptText String text to display on the accept button
Clickwrap, HMAC-Clickwrap rejectText String text to display on the reject button
Clickwrap, HMAC-Clickwrap HMACsigner String a comma delimited list of the answers that store the signer's identity. This is written as answern. For example, answer1, answer2, and so on. Note that this parameter applies only to HMAC-Clickwrap signatures
Clickwrap, HMAC-Clickwrap HMACSecret String a comma delimited list of the answers that store the shared secret. This is written as answern. For example, answer1, answer2, and so on. Note that this parameter applies only to HMAC-Clickwrap signatures
Clickwrap, HMAC-Clickwrap readonly String a comma delimited list of the answers that should be read-only. This is written as answern. For example, answer1, answer2, and so on. Note that this parameter applies only to HMAC-Clickwrap signatures
CryptoAPI csp determined by form viewing program Cryptographic Service Provider (ie Microsoft™ Base Cryptographic Provider v1.0)
CryptoAPI csptype rsa_full full RSA implementation (this is the default)
CryptoAPI csptype rsa_sig for a CSP that supplies only RSA signature algorithms
CryptoAPI csptype dss for a CSP that supplies algorithms compliant with the Digital signature Standard
CryptoAPI csptype dss_dh for a CSP that supplies DSS compliant algorithms and Diffie-Hellman encryption
CryptoAPI csptype fortezza for a CSP that supplies Fortezza algorithms
CryptoAPI csptype
Note: Instead of using one of the previous settings for csptype, the numeric value that is defined for it in the cryptographic API may be used. For example, csptype=dss and csptype=3 produce the same result.
Note: Instead of using one of the previous settings for csptype, the numeric value that is defined for it in the cryptographic API may be used. For example, csptype=dss and csptype=3 produce the same result.
CryptoAPI hashalg sha1 hash algorithm with 160-bit message digest. This is the default setting.
CryptoAPI hashalg sha256 hash algorithm with 256-bit message digest
CryptoAPI hashalg sha384 hash algorithm with 384-bit message digest
CryptoAPI hashalg sha512 hash algorithm with 512-bit message digest
CryptoAPI hashalg md5 hash algorithm with 128-bit message digest
Entrust hashalg sha1 hash algorithm with 160-bit message digest. This is the default setting.
Entrust hashalg md5 hash algorithm with 128-bit message digest
Netscape hashalg sha1 hash algorithm with 160-bit message digest. This is the default setting.
Netscape hashalg sha256 hash algorithm with 256-bit message digest
Netscape hashalg sha384 hash algorithm with 384-bit message digest
Netscape hashalg sha512 hash algorithm with 512-bit message digest
Netscape hashalg md5 hash algorithm with 128-bit message digest
signaturePad TSP String defines the preferred signature pad software/hardware to use. Valid settings are:
  • Interlink
  • Topaz
  • WinTab

If no setting is specified, the form viewing software will determine which hardware is available, and will default to either Interlink or Topaz first and WinTab second.
signaturePad hashalg sha1 hash algorithm with 160-bit message digest. This is the default setting.
signaturePad hashalg md5 hash algorithm with 128-bit message digest
signaturePad titleText String text to display for the main title of the signature dialog box
signaturePad mainPrompt String text to display for the main prompt
signaturePad mainText String text to display for the main text
signaturePad question1Text String label for the first question
signaturePad answer1Text String default answer to the first question; user can overwrite
signaturePad question2Text String label for the second question
signaturePad answer2Text String default answer to the second question; user can overwrite
signaturePad question3Text String label for the third question
signaturePad answer3Text String default answer to the third question; user can overwrite
signaturePad question4Text String label for the forth question
signaturePad answer4Text String default answer to the forth question; user can overwrite
signaturePad question5Text String label for the fifth question
signaturePad answer5Text String default answer to the fifth question; user can overwrite
signaturePad echoPrompt String text to display for the echo prompt
signaturePad echoText String text to display for the signer to echo
signaturePad buttonPrompt String text to display before the accept and reject buttons
signaturePad acceptText String text to display on the accept button
signaturePad rejectText String text to display on the reject button
signaturePad readonly String a comma delimited list of the answers that should be read-only. This is written as answern. For example, answer1, answer2, and so on.
signaturePad startText String text to display on the button that starts the signature capture
signaturePad endText String text to display on the button that ends the signature capture
signaturePad penColor String the color to use when drawing the signature on the screen. This is either a color name or a comma separated list of RGB values.
signaturePad backgroundColor String the color to use for the background of the signature graphic. This is either a color name or a comma separated list of RGB values.
Silanis lock on sets the signature to lock all signed data. This prevents the user from changing data once it has been signed. By default, all signature types lock the data.
Silanis lock off prevents the signature from locking the data. This means users will be able to change signed data. Note that changes to signed data will still break the signature.

Example

This example shows a button configured for a CryptoAPI signature.

   <button sid="empSigButton">
      <type>signature</type>
      <value compute="signer"></value>
      <signer></signer>
      <format>
         <datatype>string</datatype>
         <constraints>
            <mandatory>on</mandatory>
         </constraints>
      </format>
      <signformat>         application/vnd.xfdl;
         csp="Microsoft Base Cryptographic Provider v1.0";
         csptype=rsa_full; hashalg=sha1
      </signformat>
      <signoptions>
         <filter>omit</filter>
         <optiontype>triggeritem</optiontype>
         <optiontype>coordinates</optiontype>
      </signoptions>
      <signitemrefs>
         <filter>omit</filter>
         <itemref>PAGE1.mgrSigButton</itemref>
         <itemref>PAGE1.admSigButton</itemref>
         <itemref>PAGE1.empsignature</itemref>
         <itemref>PAGE1.mgrsignature</itemref>
         <itemref>PAGE1.admsignature</itemref>
      </signitemrefs>
   <!-- The items listed previously MUST have itemlocation
   options with absolute and extent as the last
   settings in order for the filter under to
   be sufficient in terms of security -->
      <signoptionrefs>
         <filter>keep</filter>
         <optionref>PAGE1.mgrSigButton.itemlocation</optionref>
         <optionref>PAGE1.admSigButton.itemlocation</optionref>
         <optionref>PAGE1.empsignature.itemlocation</optionref>
         <optionref>PAGE1.mgrsignature.itemlocation</optionref>
         <optionref>PAGE1.admsignature.itemlocation</optionref>
      </signoptionrefs>
      <signature>empsignature</signature>
   </button>

This example shows a button configured for a Clickwrap signature.

   <button sid="empSigButton">
      <type>signature</type>
      <value compute="signer"></value>
      <signer></signer>
      <format>
         <datatype>string</datatype>
         <constraints>
            <mandatory>on</mandatory>
         </constraints>
      </format>
      <signformat>application/vnd.xfdl; 
         engine="ClickWrap"; hashalg="md5";
         titleText="Document Acceptance";
         echoPrompt="Type the following:"; 
         echoText="I agree";question1Text="Name:";
         question2Text="Employee ID #:"
      </signformat>
      <signoptions>
         <filter>omit</filter>
         <optiontype>triggeritem</optiontype>
         <optiontype>coordinates</optiontype>
      </signoptions>
      <signitemrefs>
         <filter>omit</filter>
         <itemref>PAGE1.mgrSigButton</itemref>
         <itemref>PAGE1.admSigButton</itemref>
         <itemref>PAGE1.empsignature</itemref>
         <itemref>PAGE1.mgrsignature</itemref>
         <itemref>PAGE1.admsignature</itemref>
      </signitemrefs>
      <!-- The items listed previously MUST have itemlocation
      options with absolute and extent as the last
      settings in order for the filter under to
      be sufficient in terms of security -->
      <signoptionrefs>
         <filter>keep</filter>
         <optionref>PAGE1.mgrSigButton.itemlocation</optionref>
         <optionref>PAGE1.admSigButton.itemlocation</optionref>
         <optionref>PAGE1.empsignature.itemlocation</optionref>
         <optionref>PAGE1.mgrsignature.itemlocation</optionref>
         <optionref>PAGE1.admsignature.itemlocation</optionref>
      </signoptionrefs>
      <signature>empsignature</signature>
   </button>

Usage details

  1. An XFDL Viewer automatically copies the signformat option from a signature button to its associated signature item.
  2. signformat is an optional setting for a button item, but is mandatory for a signature item.
Parent topic: XFDL options and array elements