128 Bit vs 256 Bit Encryption SSL: What You Need to Know

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Ever wonder what 128 or 256 bit encryption means? Here’s your answer

As you’re reading this blog post, it’s highly likely that you’ve come across various SSL certificate options of 128 bit and 256 bit encryption strength. And now you’re probably wondering what the difference is between the two and which is more effective. On the surface, it’s evident that the bigger the encryption strength, the better it is. However, there’s more to 128 bit vs 256 bit encryption than just the numbers.

In this post, we’ll outline what both 128 bit and 256 bit encryption mean, how they differ, and which one is better for you.

Let’s First Understand How Encryption Works

We all send and receive a ton of information on the internet every day such as financial details, passwords, private messages, pictures, etc. When this information transmits from one location to another, there’s a risk of people with ill intentions stealing and tampering with that confidential data.

That’s where encryption comes in.

Encryption is the process in which the data we send/receive is converted into an unreadable format to prevent any third party from reading and altering it. It’s what keeps us safe on the internet so that we can use it without being insecure about our private information.

The Role of Encryption Keys in Encryption

The entire operation of turning our data into a scrambled format is done using two encryption keys — public and private keys. Both these keys are distinct, yet they’re related mathematically.

When a user sends data to a server, it’s encrypted using the public key. And this data, as you may have rightly guessed, can only be decrypted using the corresponding private key. The intended recipient keeps the private key for obvious reasons. 

This particular method of encryption is called asymmetric encryption, or public key encryption. A significant advantage of this encryption method is that it allows only the intended recipients to see the data, as verification of each party is ensured through the encryption keys. However, this method comes with a major pitfall: It takes a lot more time for the data to be encrypted as each time the data is transmitted, the verification of the opposite key is done.

This is where a method of encryption known as symmetric encryption saves the day.

Once both parties have validated private and the public key of each other using asymmetric encryption, the encryption of the data using a single key begins. This is called symmetric encryption. And this is the key that usually has a length of 128 bits or 256 bits.

What Do 128 Bit and 256 Bit Mean in Encryption?

As we discussed earlier, when talking about 128 bit vs 256 bit encryption, the numbers 128 and 256 represent the encryption key length. It means that your data is encrypted (locked) and decrypted (unlocked) using a key of 128 or 256 bits. (Note: Every bit represents a binary digit, either 1 or 0.) The key having 128 bits of length will have 2128 possible combinations, and the key of 256 bits will have 2256 possible combinations.

If hackers want to crack this key, they will likely have to try most of these combinations. Whether it’s 128 or 256 bits, no supercomputer will be able to crack the key in any practical timeframe.

Without the assistance of quantum computing (which is still nowhere near ready for real-world use), here’s how much time it’ll take to crack the key:

Key Size Time to Crack
56-bit 399 Seconds
128-bit 1.02 x 1018 years
192-bit 1.872 x 1037 years
256-bit  3.31 x 1056 years

There’s More to a Key Than Just Its Length

It’s quite obvious that the higher the key length, the better it is for you. However, you must take your server configuration and browser capabilities into consideration. So, if you’ve purchased an SSL certificate that has the encryption strength of 256 bits, it’s possible that encryption might be done by a key of 40 bits of length. Please note that the maximum encryption strength that can be applied will be 256 bits. However, you must configure your server accordingly.

128 Bit vs 256 Bit: What’s the Conclusion?

As you saw, the amount of time it would take to break 128 or 256 bit encryption is beyond our imagination. You should be okay with either of them until quantum computing technology advances to a point that it’s not longer available in just a laboratory setting and poses a danger in the real world.

However, until that happens — and given that 256 bit encryption is notably harder to crack than 128 bit encryption — we’d recommend you go with the 256 bit. But you should always keep in mind that the encryption strength isn’t everything that matters.

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