HTML 5 <keygen> Tag

This tag has now been removed from the HTML5 specification (which is still in draft status at time of writing). Rather than remove this article altogether, I have decided to keep it here for reference.

The HTML <keygen> tag is used for generating a key pair. This can be used for generating signed certificates, which can be used to authenticate to services that use Transport Layer Security (TLS) and certificate authentication. When the control's form is submitted, the private key is stored in the local keystore, and the public key is packaged and sent to the server.

When used in a form, the <keygen> element will provide the user with a range of key size options. It may also provide a choice of where to generate the key, for example in a smart card or in software and stored on disk. In this case the user's browser would need to be configured to support cryptographic hardware.

The <keygen> element was introduced in HTML5.

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Attributes

HTML tags can contain one or more attributes. Attributes are added to a tag to provide the browser with more information about how the tag should appear or behave. Attributes consist of a name and a value separated by an equals (=) sign, with the value surrounded by double quotes. Here's an example, style="color:black;".

There are 3 kinds of attributes that you can add to your HTML tags: Element-specific, global, and event handler content attributes.

The attributes that you can add to this tag are listed below.

Element-Specific Attributes

The following table shows the attributes that are specific to this tag/element.

AttributeDescription
autofocusAutomatically gives focus to this control when the page loads. This allows the user to start using the control without having to select it first. There must not be more than one element in the document with the autofocus attribute specified.

This is a boolean attribute. If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace (i.e. either autofocus or autofocus="autofocus").

Possible values:

  • [Empty string]
  • autofocus
challengeSpecifies whether or not the value of the keygen is be challenged when submitted.
disabledDisables the control. The control won't accept changes from the user. It also cannot receive focus and will be skipped when tabbing.

This is a boolean attribute. If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace (i.e. either disabled or disabled="disabled").

Possible values:

  • [Empty string]
  • disabled
formSpecifies the ID of a form to which this control belongs.

Possible values:

[The ID of a form element in the element's owner Document]
keytypeSpecifies a key type. For example, the value "RSA" specifies an RSA key.
nameAssigns a name to the input control.

Global Attributes

The following attributes are standard across all HTML 5 tags (although the tabindex attribute does not apply to dialog elements).

For a full explanation of these attributes, see HTML 5 global attributes.

Event Handler Content Attributes

Event handler content attributes enable you to invoke a script from within your HTML. The script is invoked when a certain "event" occurs. Each event handler content attribute deals with a different event.

For a full list of event handlers, see HTML 5 event handler content attributes.

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