4.10.14. The Keygen Element

The user agent may expose a user interface for each keygen element to allow the user to configure settings of the element's key pair generator, e.g. the key length.

The reset algorithm for keygen elements is to set these various configuration settings back to their defaults.

The element's value is the string returned from the following algorithm:

1. Use the appropriate step from the following list:

   If the keytype attribute is in the RSA state

   Generate an RSA key pair using the settings given by the user, if appropriate, using the md5WithRSAEncryption RSA signature algorithm (the signature algorithm with MD5 and the RSA encryption algorithm) referenced in section 2.2.1 ("RSA Signature Algorithm") of RFC 3279, and defined in RFC 2313. [RFC3279] [RFC2313]

   Otherwise, the keytype attribute is in the unknown state

   The given key type is not supported. Return the empty string and abort this algorithm.

   Let private key be the generated private key.

   Let public key be the generated public key.

   Let signature algorithm be the selected signature algorithm.

2. If the element has a challenge attribute, then let challenge be that attribute's value. Otherwise, let challenge be the empty string.

3. Let algorithm be an ASN.1 AlgorithmIdentifier structure as defined by RFC 5280, with the algorithm field giving the ASN.1 OID used to identify signature algorithm, using the OIDs defined in section 2.2 ("Signature Algorithms") of RFC 3279, and the parameters field set up as required by RFC 3279 for AlgorithmIdentifier structures for that algorithm. [X690] [RFC5280] [RFC3279]

4. Let spki be an ASN.1 SubjectPublicKeyInfo structure as defined by RFC 5280, with the algorithm field set to the algorithm structure from the previous step, and the subjectPublicKey field set to the BIT STRING value resulting from ASN.1 DER encoding the public key. [X690] [RFC5280]

5. Let publicKeyAndChallenge be an ASN.1 PublicKeyAndChallenge structure as defined below, with the spki field set to the spki structure from the previous step, and the challenge field set to the string challenge obtained earlier. [X690]

6. Let signature be the BIT STRING value resulting from ASN.1 DER encoding the signature generated by applying the signature algorithm to the byte string obtained by ASN.1 DER encoding the publicKeyAndChallenge structure, using private key as the signing key. [X690]

7. Let signedPublicKeyAndChallenge be an ASN.1 SignedPublicKeyAndChallenge structure as defined below, with the publicKeyAndChallenge field set to the publicKeyAndChallenge structure, the signatureAlgorithm field set to the algorithm structure, and the signature field set to the BIT STRING signature from the previous step. [X690]

8. Return the result of base64 encoding the result of ASN.1 DER encoding the signedPublicKeyAndChallenge structure. [RFC4648] [X690]

The data objects used by the above algorithm are defined as follows. These definitions use the same "ASN.1-like" syntax defined by RFC 5280. [RFC5280]

PublicKeyAndChallenge ::= SEQUENCE { spki SubjectPublicKeyInfo, challenge IA5STRING}SignedPublicKeyAndChallenge ::= SEQUENCE { publicKeyAndChallenge PublicKeyAndChallenge, signatureAlgorithm AlgorithmIdentifier, signature BIT STRING}

Constraint validation: The keygen element is barred from constraint validation.

The challenge IDL attribute must reflect the content attribute of the same name.

The keytype IDL attribute must reflect the content attribute of the same name, limited to only known values.

The type IDL attribute must return the value "keygen".

The willValidate, validity, and validationMessage IDL attributes, and the checkValidity() and setCustomValidity() methods, are part of the constraint validation API. The labels IDL attribute provides a list of the element's labels. The autofocus, disabled, form, and name IDL attributes are part of the element's forms API.

The element has a value mode flag which is either value or default. Initially, the value mode flag must be set to default.

The element also has a default value. Initially, the default value must be the empty string.

When the value mode flag is in mode default, the contents of the element represent both the value of the element and its default value. When the value mode flag is in mode value, the contents of the element represent the value of the element only, and the default value is only accessible using the defaultValue IDL attribute.

Whenever the element's descendants are changed in any way, if the value mode flag is in mode default, the element's default value must be set to the value of the element's textContent IDL attribute.

The reset algorithm for output elements is to set the element's value mode flag to default and then to set the element's textContent IDL attribute to the value of the element's default value (thus replacing the element's child nodes).

The value IDL attribute must act like the element's textContent IDL attribute, except that on setting, in addition, before the child nodes are changed, the element's value mode flag must be set to value.

The defaultValue IDL attribute, on getting, must return the element's default value. On setting, the attribute must set the element's default value, and, if the element's value mode flag is in the mode default, set the element's textContent IDL attribute as well.

The type attribute must return the string "output".

The htmlFor IDL attribute must reflect the for content attribute.

The willValidate, validity, and validationMessage IDL attributes, and the checkValidity() and setCustomValidity() methods, are part of the constraint validation API. The labels IDL attribute provides a list of the element's labels. The form and name IDL attributes are part of the element's forms API.

User agent requirements: If the value attribute is omitted, then the progress bar is an indeterminate progress bar. Otherwise, it is a determinate progress bar.

If the progress bar is a determinate progress bar and the element has a max attribute, the user agent must parse the max attribute's value according to the rules for parsing floating-point number values. If this does not result in an error, and if the parsed value is greater than zero, then the maximum value of the progress bar is that value. Otherwise, if the element has no max attribute, or if it has one but parsing it resulted in an error, or if the parsed value was less than or equal to zero, then the maximum value of the progress bar is 1.0.

If the progress bar is a determinate progress bar, user agents must parse the value attribute's value according to the rules for parsing floating-point number values. If this does not result in an error, and if the parsed value is less than the maximum value and greater than zero, then the current value of the progress bar is that parsed value. Otherwise, if the parsed value was greater than or equal to the maximum value, then the current value of the progress bar is the maximum value of the progress bar. Otherwise, if parsing the value attribute's value resulted in an error, or a number less than or equal to zero, then the current value of the progress bar is zero.

UA requirements for showing the progress bar: When representing a progress element to the user, the UA should indicate whether it is a determinate or indeterminate progress bar, and in the former case, should indicate the relative position of the current value relative to the maximum value.

If the progress bar is an indeterminate progress bar, then the position IDL attribute must return −1. Otherwise, it must return the result of dividing the current value by the maximum value.

If the progress bar is an indeterminate progress bar, then the value IDL attribute, on getting, must return 0. Otherwise, it must return the current value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the value content attribute must be set to that string.

Setting the value IDL attribute to itself when the corresponding content attribute is absent would change the progress bar from an indeterminate progress bar to a determinate progress bar with no progress.

The max IDL attribute must reflect the content attribute of the same name, limited to numbers greater than zero. The default value for max is 1.0.

The labels IDL attribute provides a list of the element's labels.

User agent requirements: User agents must parse the min, max, value, low, high, and optimum attributes using the rules for parsing floating-point number values.

User agents must then use all these numbers to obtain values for six points on the gauge, as follows. (The order in which these are evaluated is important, as some of the values refer to earlier ones.)

The minimum value

If the min attribute is specified and a value could be parsed out of it, then the minimum value is that value. Otherwise, the minimum value is zero.

The maximum value

If the max attribute is specified and a value could be parsed out of it, then the candidate maximum value is that value. Otherwise, the candidate maximum value is 1.0.

If the candidate maximum value is greater than or equal to the minimum value, then the maximum value is the candidate maximum value. Otherwise, the maximum value is the same as the minimum value.

The actual value

If the value attribute is specified and a value could be parsed out of it, then that value is the candidate actual value. Otherwise, the candidate actual value is zero.

If the candidate actual value is less than the minimum value, then the actual value is the minimum value.

Otherwise, if the candidate actual value is greater than the maximum value, then the actual value is the maximum value.

Otherwise, the actual value is the candidate actual value.

The low boundary

If the low attribute is specified and a value could be parsed out of it, then the candidate low boundary is that value. Otherwise, the candidate low boundary is the same as the minimum value.

If the candidate low boundary is less than the minimum value, then the low boundary is the minimum value.

Otherwise, if the candidate low boundary is greater than the maximum value, then the low boundary is the maximum value.

Otherwise, the low boundary is the candidate low boundary.

The high boundary

If the high attribute is specified and a value could be parsed out of it, then the candidate high boundary is that value. Otherwise, the candidate high boundary is the same as the maximum value.

If the candidate high boundary is less than the low boundary, then the high boundary is the low boundary.

Otherwise, if the candidate high boundary is greater than the maximum value, then the high boundary is the maximum value.

Otherwise, the high boundary is the candidate high boundary.

The optimum point

If the optimum attribute is specified and a value could be parsed out of it, then the candidate optimum point is that value. Otherwise, the candidate optimum point is the midpoint between the minimum value and the maximum value.

If the candidate optimum point is less than the minimum value, then the optimum point is the minimum value.

Otherwise, if the candidate optimum point is greater than the maximum value, then the optimum point is the maximum value.

Otherwise, the optimum point is the candidate optimum point.

All of which will result in the following inequalities all being true:

• minimum value ≤ actual value ≤ maximum value
• minimum value ≤ low boundary ≤ high boundary ≤ maximum value
• minimum value ≤ optimum point ≤ maximum value

UA requirements for regions of the gauge: If the optimum point is equal to the low boundary or the high boundary, or anywhere in between them, then the region between the low and high boundaries of the gauge must be treated as the optimum region, and the low and high parts, if any, must be treated as suboptimal. Otherwise, if the optimum point is less than the low boundary, then the region between the minimum value and the low boundary must be treated as the optimum region, the region from the low boundary up to the high boundary must be treated as a suboptimal region, and the remaining region must be treated as an even less good region. Finally, if the optimum point is higher than the high boundary, then the situation is reversed; the region between the high boundary and the maximum value must be treated as the optimum region, the region from the high boundary down to the low boundary must be treated as a suboptimal region, and the remaining region must be treated as an even less good region.

UA requirements for showing the gauge: When representing a meter element to the user, the UA should indicate the relative position of the actual value to the minimum and maximum values, and the relationship between the actual value and the three regions of the gauge.

The value IDL attribute, on getting, must return the actual value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the value content attribute must be set to that string.

The min IDL attribute, on getting, must return the minimum value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the min content attribute must be set to that string.

The max IDL attribute, on getting, must return the maximum value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the max content attribute must be set to that string.

The low IDL attribute, on getting, must return the low boundary. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the low content attribute must be set to that string.

The high IDL attribute, on getting, must return the high boundary. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the high content attribute must be set to that string.

The optimum IDL attribute, on getting, must return the optimum value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the optimum content attribute must be set to that string.

The labels IDL attribute provides a list of the element's labels.

The rules in this section are complicated by the fact that although conforming documents will never contain nested form elements, it is quite possible (e.g. using a script that performs DOM manipulation) to generate documents that have such nested elements. They are also complicated by rules in the HTML parser that, for historical reasons, can result in a form-associated element being associated with a form element that is not its ancestor.

When a form-associated element is created, its form owner must be initialized to null (no owner).

When a form-associated element is to be associated with a form, its form owner must be set to that form.

When a form-associated element or one of its ancestors is inserted into a Document, then the user agent must reset the form owner of that form-associated element. The HTML parser overrides this requirement when inserting form controls.

When an element is removed from a Document resulting in a form-associated element and its form owner (if any) no longer being in the same home subtree, then the user agent must reset the form owner of that form-associated element.

When a form-associated element's form attribute is set, changed, or removed, then the user agent must reset the form owner of that element.

When a form-associated element has a form attribute and the ID of any of the elements in the Document changes, then the user agent must reset the form owner of that form-associated element.

When a form-associated element has a form attribute and an element with an ID is inserted into or removed from the Document, then the user agent must reset the form owner of that form-associated element.

When the user agent is to reset the form owner of a form-associated element, it must run the following steps:

1. If the element's form owner is not null, and the element's form content attribute is not present, and the element's form owner is its nearest form element ancestor after the change to the ancestor chain, then do nothing, and abort these steps.

2. Let the element's form owner be null.

3. If the element has a form content attribute and is itself in a Document, then run these substeps:

   1. If the first element in the Document to have an ID that is case-sensitively equal to the element's form content attribute's value is a form element, then associate the form-associated element with that form element.

   2. Abort the "reset the form owner" steps.

4. Otherwise, if the form-associated element in question has an ancestor form element, then associate the form-associated element with the nearest such ancestor form element.

5. Otherwise, the element is left unassociated.

... <form id="a">  <div id="b"></div> </form> <script>  document.getElementById('b').innerHTML = '<table><tr><td><form id="c"><input id="d"></table>' + '<input id="e">'; </script>...

Form-associated elements have a form IDL attribute, which, on getting, must return the element's form owner, or null if there isn't one.