How to Encrypt Compressed Data Using zlib and CryptoJS in Node.js

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In this guide, we'll explore how to effectively compress an object using zlib and encrypt it with CryptoJS's AES encryption algorithm. We'll guide you through the steps to avoid common pitfalls, ensuring you can retrieve your original data seamlessly.

Understanding the Problem

You might be using the following code to deflate (compress) an object and then encrypt it:

[[See Video to Reveal this Text or Code Snippet]]

When you try to decompress the data, you might encounter an error:

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This error typically indicates that the zlib header was lost during the conversion of compressed to a string.

The Solution

Step 1: Preserve the zlib Header

To ensure that the zlib header remains intact during encryption, we need to convert the compressed data into a Base64 representation before encrypting. Here's how:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Decrypt and Inflate

When you decrypt the data, you will also need to reverse this process:

[[See Video to Reveal this Text or Code Snippet]]

Complete Code Example

Here’s the complete code showcasing the above changes:

[[See Video to Reveal this Text or Code Snippet]]

Output

When you run this code, you should see an output similar to:

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An Alternate Approach: Encrypt First, Then Compress

While the approach above works well, a more efficient method is to encrypt the data before compressing it. This strategy can lead to a smaller final output size. Here's how:

Encrypt the object's string representation.

Compress the encrypted string.

Revised Code Example

[[See Video to Reveal this Text or Code Snippet]]

Final Output

The output will resemble:

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Conclusion

By following these methods, you ensure the integrity and security of your data, keeping it safe for transmission and storage. Happy Coding!