HTML <keygen> Tag: Usage, Attributes, and Examples

By Cristian G. Guasch •  Updated: 09/25/23 •  10 min read

Navigating the vast ocean of HTML tags can sometimes feel like you’re exploring a never-ending maze. One such intriguing corner of this labyrinth is the <keygen> tag. This lesser-known but highly useful tag, which was used in HTML5, played a crucial role in form encryption. Although it’s no longer supported in HTML5 or modern browsers, understanding its functionality can provide valuable insight into past encryption practices.

The <keygen> tag essentially facilitated key-pair generation — a critical component of online security measures back in the day. On encountering this tag, your browser would generate a public-private key pair on form submission. The private key remained stored locally on your machine while the public one got sent to the server for certification.

However, let’s not dwell too much on mystery and nostalgia! It’s important to remember that even though the <keygen> tag is deprecated now (meaning it doesn’t work anymore), studying its usage and attributes still carries educational merit. After all, knowledge of how things were done previously often helps us understand present technologies better! So stick around as we dive deeper into what made this seemingly obscure tag tick and some examples of how it was employed in real-world scenarios.

Let me dive right into the heart of our topic: Understanding the HTML <keygen> tag. If you’re like most web developers, you’ve likely encountered this little-known tag in your coding adventures. But what is it? What does it do? And more importantly, how can you use it effectively?

The <keygen> tag is a part of HTML5 and was initially intended to facilitate key pair generation. The idea was for it to generate a public-private key pair when submitting forms on a webpage. This would then be used for client-side certificate authentication.

Sounds confusing? Let’s break it down with an example:

<form action="/submit_form" method="post">
  Username: <input type="text" name="username"><br>
  Key: <keygen name="security"><br>
  <input type="submit">

In this block of code, you’ll notice that we have a form with three inputs: one for the username, another being the <keygen> tag (named “security”), and finally, a submit button.

When the user clicks submit after filling out their username, the browser generates two keys – one public and one private. The public key gets sent along with the form data while the private key stays stored in the user’s system.

However, there’s something important I need to point out: as useful as this may sound, as of now, all major browsers including Google Chrome and Mozilla Firefox have dropped support for this tag! So if you’re thinking about using <keygen>, I’d advise caution.

It’s also worth mentioning that there aren’t many attributes associated with <keygen>. It has only three attributes: name, challenge, and keytype. Here’s how each works:

There you have it! That’s a quick rundown on HTML <keygen>. Remember, while it might seem intriguing, its lack of browser support makes it a risky choice for your web development needs. But now that you know about it, you’re one step closer to mastering every corner of HTML5!

Breaking Down the Attributes of HTML <keygen>

Diving straight into the heart of the matter, let’s unravel the attributes associated with HTML <keygen> tag. It’s worth noting that this tag is not supported in HTML5, but understanding its usage can still be beneficial.

The first attribute we’ll examine is ‘name’. This is a mandatory one and it helps specify a name for the key pair generated by <keygen>. Here’s an example:

<keygen name="user_key">

Next up, we have ‘autofocus’. When included, it allows the page to automatically focus on this element when it loads. A typical use case might look like this:

<keygen autofocus>

Then there’s ‘challenge’. It provides a random string that gets encrypted with the private key to ensure authenticity. But remember, no browsers are currently using this attribute! An illustrative snippet would be:

<keygen challenge="random_string">

A common mistake I’ve noticed among beginners involves confusing ‘challenge’ with providing security against malicious activities. In reality, it’s just for checking authenticity.

The final attribute we’re exploring today is ‘disabled’. As you’d expect, adding this prevents any user interaction with the element – useful in certain circumstances!

<keygen disabled>

Hopefully now you’re more comfortable navigating your way around HTML <keygen>’s attributes. Stay tuned for our next section where we’ll dive even deeper!

Practical Usage Scenarios for <keygen> in HTML

Diving straight into it, the <keygen> tag in HTML is an interesting little element. It’s been part of HTML since the early days, but you might not have crossed paths with it yet. So when and why should we use it? Let’s explore some practical scenarios.

Firstly, the <keygen> tag is primarily used for generating a pair of keys – one private and one public. This comes in handy when dealing with form data that needs to be securely encrypted before being sent off to a server. Say you’re building an online banking application; using <keygen>, users can generate their own unique key pairs right within their browsers!

Here’s how you’d implement this:

<form action="submitForm.cgi" method="post">
  Username: <input type="text" name="userName"><br>
  Key: <keygen name="userKey">
  <input type="submit">

In this example, when the user clicks on “Submit”, they are prompted to create a new key pair. The public key gets sent along with other form data (in our case, ‘Username’), while the private key remains safely stored in user’s browser.

However, there are important considerations too! One common mistake is overlooking browser support – while most modern browsers still recognize <keygen>, it has officially been deprecated from HTML5 standards due to lack of adoption and better alternatives like JavaScript Web Cryptography API.

Another area where <keygen> finds its use is client certificate creation. Suppose your web app requires clients to present certificates for mutual SSL authentication – here again, using <keygen> users can generate these certificates directly in-browser. But remember! Always validate such certificates on server-side as well.

So yes, even though HTML <keygen> tag may seem archaic, it still holds its own in certain scenarios. But with its deprecation and the rise of more flexible APIs, don’t be surprised if you never actually use this tag in your web development journey!

Real-World Examples of HTML <keygen> Tag Application

Let’s dive right into the deep end with some real-world examples of the HTML <keygen> tag in action. It’s worth noting that this element was initially used by Netscape for SSL certificate generation in forms but has since been deprecated in HTML5.

Take the case of encrypted email services, for instance. Back when it was still current, you might’ve found the <keygen> tag being used to generate a key pair on user registration. The private key would stay on the user’s device while the public one goes to the server. This way, only encrypted messages could be read on that particular device.

<form action="process.php" method="post">
  Username: <input type="text" name="username"><br>
  Password: <input type="password" name="pwd"><br>
  Generate Public/Private Key Pair: 
  <keygen name="security" challenge="random_string_here">
  <input type="submit">

In another scenario, consider online banking systems or secure intranets. Here too, you’d have seen <keygen> at work if you were around before its depreciation. It helped generate client certificates for authentication during login, adding an extra layer of security.

<form action="/login.php" method=post enctype='multipart/form-data'>
    <!-- some input fields here for username and password -->
    Client Certificate:
    <keygen name=spkacChallenge challenge=some_challenge_string>

As we look back now though, it’s clear there were issues with compatibility across different browsers and devices – Internet Explorer never supported it fully while Chrome and Firefox dropped support eventually too. Not to mention that using JavaScript-based libraries like Forge or Web Cryptography API offers more flexibility and control over keys generation process these days.

In spite of its limitations and ultimate deprecation, the <keygen> tag was indeed a handy tool in its time for creating secure web applications. Its footprint can still be found in older systems that haven’t been updated to HTML5 or modern encryption libraries yet.

Common Mistakes

While it’s no longer relevant, let’s cover some common mistakes developers made with the <keygen> tag:

So there you have it – a look back at HTML’s deprecated but once useful <keygen> tag!

Concluding Thoughts on Using the HTML <keygen> Tag

I’ve spent a good amount of time discussing the ins and outs of the HTML <keygen> tag. Now, I’d like to draw your attention to some key points about its usage, attributes, and examples.

Firstly, keep in mind that this tag is not supported in HTML5. So if you’re working with modern coding standards, it’s best to avoid using it. Instead, consider other forms of client authentication such as SSL certificates or JWT tokens.

<keygen name="security">

Remember that when used correctly in older versions of HTML, <keygen> can generate a key pair for user authentication. But remember it isn’t a one-size-fits-all solution for security.

Next up are attributes. The name attribute is an essential component – without it, the <keygen> tag won’t function properly!

Common mistakes? One that jumps out at me involves forgetting to include a form around the <keygen> element:

<form action="/submit_key.cgi" method="post">
  Key size: 
  <keygen name="rsa_keypair" challenge="random_chars" keytype="RSA">

Without wrapping this tag in a form element, your keys won’t be generated – trust me on this one!

Now that we’ve covered these bases – what’s left? Not much really! Just remember:

Master these points and you’ll have no problem navigating your way around this particular piece of code!

Cristian G. Guasch

Hey! I'm Cristian Gonzalez, I created HTML Easy to help you learn HTML easily and fast.

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