Visual Cryptography: Basics and Best Practices
Written by  Daisie Team
Published on 9 min read


  1. What is Visual Cryptography?
  2. How Visual Cryptography Works
  3. Types of Visual Cryptography
  4. Applications of Visual Cryptography
  5. Advantages and Limitations of Visual Cryptography
  6. How to Implement Visual Cryptography
  7. Best Practices for Visual Cryptography
  8. Future Trends in Visual Cryptography

Picture this: You're trying to securely send an image or text, and you want to ensure only the intended recipient can make sense of it. No, we're not talking about password protection or fancy software. We're talking about a field called visual cryptography. Consider this your introduction to visual cryptography, where we'll dive into the basics and explore some best practices.

What is Visual Cryptography?

Visual cryptography is a cool way to encrypt information — primarily images or text — in such a manner that decoding can be achieved by the human eye. It was first proposed by Moni Naor and Adi Shamir in 1994. Instead of relying on complex algorithms or computation-power, this method uses the human eye's natural ability to combine layered images.

Here's a simple way to understand it: Imagine you have a picture that you want to share with your friend, but you don't want anyone else to see it. Visual cryptography allows you to split this image into two or more 'shares'. Each share looks like random black and white pixels — nothing like the original image. But when you stack these shares together, voila! Your original image appears.

What makes visual cryptography so unique is the fact that you don't need any special software or tools to decrypt the image. All you need is the ability to put two images together and your own eyes. So, whether you're an aspiring coder looking for a fun project, or a seasoned professional seeking more secure ways to share visual data, understanding visual cryptography should be on your to-do list.

Now that you've had an introduction to visual cryptography, let's delve deeper into how it works, its different types, and its applications. We'll also discuss its advantages and limitations, how to implement it, and even take a peek into its future trends.

How Visual Cryptography Works

Visual cryptography works on a pretty simple and neat concept. It splits an image into multiple layers or 'shares'. Think of these shares like layers of transparent film. On their own, these layers look like a bunch of random black and white pixels. They don't reveal anything about the original image.

But when you stack these shares on top of each other, the magic of visual cryptography comes to life. The combined layers reveal the original image. The best part? You don't need any complex software or decryption keys. Your eyes do all the decrypting work for you.

Here's an easier way to understand this. Let's say you have a secret message that you want to share with your friend. You write this message on a piece of transparent film. Then, you create a second layer of film with a pattern of random black and white pixels. Individually, these layers mean nothing. But when you put the two layers together, your message becomes visible.

This is visual cryptography in action: simple, secure, and accessible. It's like having a secret decoder ring from your childhood, but instead of decoding secret messages, you're decoding images. And the best part about visual cryptography? It's a field that's just waiting for you to explore and experiment with.

Coming up next in our introduction to visual cryptography: the different types of visual cryptography and the various ways it is used in the real world.

Types of Visual Cryptography

Now that you have a basic understanding of how visual cryptography works, let's look at the different types of visual cryptography techniques out there. There are two main types you'll come across in your journey of understanding this fascinating subject: basic visual cryptography and extended visual cryptography.

Basic Visual Cryptography: This is the simplest form. Here, the image is divided into two shares, just like the example we used earlier. Each share looks like a random collection of black and white pixels. But when combined, they reveal the original image. This type of visual cryptography is often used for simple tasks, like sharing a secret message between two people.

Extended Visual Cryptography: This is a more advanced form. Here, the image is divided into more than two shares. Each share still looks random on its own, but when all the shares are combined, they reveal the original image. What makes this type so special is that you can also get a partial view of the image by combining some, but not all, of the shares. This is useful when you want to provide different levels of access to the same secret image.

So, which type should you use? Well, that depends on your needs. If you're just getting started with visual cryptography, the basic type is a good place to start. But if you're looking for more flexibility and control over who can access your secret image, then extended visual cryptography might be the way to go.

But regardless of which type you choose, remember: the goal is to keep your secret image safe and secure. And with visual cryptography, you have a fun and effective way to do just that.

Next up in our introduction to visual cryptography, we're going to explore some real-world applications of this exciting technology.

Applications of Visual Cryptography

When you think about secret codes and hidden messages, you may think of spy movies or treasure hunts. But the truth is, visual cryptography has some pretty practical applications in our everyday lives. Let's talk about a few of them, shall we?

Banking and Finance: Banks often need to transmit sensitive data, like your bank account details or credit card number. Visual cryptography can be used to encrypt this data, making it unreadable to anyone who doesn't have the right key to decode it. This can help keep your personal information safe from hackers and identity thieves.

Online Voting: In an age where more and more things are moving online, visual cryptography can help ensure the integrity of online voting systems. By using this technique, each vote can be encrypted in such a way that it can only be decrypted and counted by the authorized body, ensuring the secrecy and accuracy of the vote.

Secure Communications: Whether it's a business sharing trade secrets or a government agency transmitting classified information, visual cryptography can be used to secure these communications. By encrypting the information in a visual format, it can be safely transmitted without fear of interception or unauthorized access.

These are just a few examples of how visual cryptography can be used. There are many more out there, and even more waiting to be discovered. So, the next time you're sending a secret message or protecting sensitive data, remember — visual cryptography can be your secret weapon.

Now, let's move on to the next part of our introduction to visual cryptography, where we'll discuss the advantages and limitations of this fascinating technology.

Advantages and Limitations of Visual Cryptography

The beauty of visual cryptography lies in its simplicity. You don't need to be a math whiz or a computer science expert to understand it. It's like a magic trick — simple, yet amazing. But is it all roses and rainbows? Let's dig into some pros and cons.


Firstly, visual cryptography is incredibly secure. As long as you keep your decryption key safe, it's nearly impossible for anyone else to decode your hidden message. You can send your secret love letters or your top-secret business plans without fear.

Secondly, no expensive or complex hardware is needed. All you need is a computer and the right software. This makes it accessible for everyone, from students working on a school project to businesses protecting their intellectual property.


But, like all good things, visual cryptography has its limitations too. The most notable one is that it can only be used for black and white images. If you want to send a colorful picture of your cat in a secret message, you're out of luck. For now, at least.

Also, the quality of the decrypted image can be a bit low. So if you're a perfectionist who likes everything in high definition, this might be a bit of a letdown.

That said, the advantages of visual cryptography far outweigh its limitations. It's a powerful tool that, when used properly, can help you protect your information and communicate securely. It's definitely worth learning more about, as we'll continue to do in our ongoing introduction to visual cryptography.

How to Implement Visual Cryptography

Now that we've looked at what visual cryptography is and its pros and cons, let's get to the fun part — implementing it. Don't worry, we won't get too technical. Besides, remember the magic trick analogy? The fun part is always the trick, not how it's done. So, let's dive in.

Step 1: Choose Your Image

First off, you need an image. Remember, it has to be a black and white image. Your image can be anything: a message, a drawing, or even a QR code. Be creative! But also remember, the simpler the image, the clearer the result will be.

Step 2: Create the Cryptographic Key

Next, you need to generate a cryptographic key. This key is another black and white image of the same size as your original image. You can create this key randomly, pixel by pixel. And remember, keep this key safe. If someone else gets their hands on it, they can decode your encrypted image.

Step 3: Encrypt Your Image

Now comes the cool part. Using the key you just created, you can now encrypt your image. This involves a bit of pixel manipulation, but the basic premise is that each pixel of your image is transformed into a pair of pixels in the encrypted image.

Step 4: Decrypt Your Image

Finally, to decrypt the image, all you need to do is place the key over the encrypted image. The magic of visual cryptography will reveal your original image. Pretty cool, right?

And there you have it — a basic introduction to visual cryptography implementation. It's simple, secure, and perfect for sharing your secret messages. So go ahead, give it a try. Who knows? You might just find it as mesmerizing as a magic trick.

Best Practices for Visual Cryptography

So, you've grasped the basic idea on how to implement visual cryptography. Great! Now, let's talk about some best practices that will help you get the most out of this fascinating technology.

1. Use Simple Images: As mentioned before, the simpler the image, the clearer the result. Complex images might end up looking muddled when decrypted.

2. Secure Your Key: The key is your secret weapon in visual cryptography. It's what keeps your images safe. So, make sure to keep it secure. Treat it as you would your house key. You wouldn't want anyone else getting their hands on it, would you?

3. Practice Pixel Precision: When creating your key and encrypting your image, each pixel matters. Be precise and meticulous. It's like putting together a puzzle — each piece needs to fit perfectly.

4. Verify Before Sharing: Always verify your encrypted image before sharing it. Decrypt it using your key and make sure the original image appears as intended.

5. Keep Learning: Visual cryptography, like any technology, is constantly evolving. Stay updated with the latest research and advancements. Remember, learning is a lifelong journey.

These best practices for visual cryptography can help you avoid common pitfalls and ensure the successful implementation of this technology. It's not just about getting the job done, but doing it well. So, keep these tips in mind as you take your first steps into the world of visual cryptography.

Now that we've got our head around the basics and best practices of visual cryptography, let's take a peek into the future trends of this intriguing field. As with any technology, visual cryptography is not static and continues to evolve rapidly. So, what's coming up next?

1. Quantum Cryptography: Quantum physics has the potential to transform the field of visual cryptography. With quantum cryptography, we could encrypt images in a way that's virtually impossible to crack, raising the bar for security.

2. AI and Machine Learning: Artificial intelligence can help improve the efficiency and accuracy of visual cryptography. For instance, machine learning algorithms could be developed to optimize the creation of cryptographic keys.

3. Combination With Other Techniques: Visual cryptography might be combined with other cryptographic techniques to enhance security. This could result in hybrid methods that provide multiple layers of protection.

4. Advances in Key Distribution: The future may see new ways to distribute keys securely. This could involve innovative use of technologies like blockchain or secure cloud storage.

5. Use in Augmented and Virtual Reality: As AR and VR technologies become more prevalent, we could see visual cryptography playing a key role in securing data within these immersive environments.

Remember, the future is not set in stone. These trends merely represent some possibilities based on current knowledge and progress. The world of visual cryptography is a dynamic one, full of potential for innovation and growth. So, keep an eye on these future trends, and who knows? You might be at the forefront of the next big breakthrough in visual cryptography!

If you enjoyed learning about visual cryptography and want to deepen your understanding of the digital economy, check out the workshop 'Crypto For Creators, Part 1: The Backbone Of The Digital Economy' by Tom Glendinning. This workshop will provide you with valuable insights into the world of cryptography and its role in the digital economy, which can be beneficial for creators and artists alike.