What is the International Data Encryption Algorithm (IDEA)?

Anton P. | September 15, 2023

The IDEA algorithm is an encryption option for converting plain text data into unreadable format. It is a symmetric-key block cipher, applying one key for encryption and decryption. 

So, the purpose of this algorithm is to support more secure communications and other digital transfers. While IDEA is secure, experts put it aside for other, likely more efficient algorithms.

Thus, we help you discover what IDEA is, how it works, and why services might opt for other methods nowadays. 

Learn about the IDEA algorithm and how it works.

What IDEA is and how it works

An International Data Encryption Algorithm (IDEA) decides how the encryption process works. Thus, one of its main characteristics is the symmetric-key block cipher. By explaining each word, we see: 

  • IDEA is a symmetric algorithm applying one key for encryption and decryption. 
  • It encrypts data not as a whole but after dividing it into 64-bit blocks. 

So, IDEA operates on 64-bit blocks and uses a 128-bit key. However, the blocks get split into four internal blocks of 16 bits. Thus, the encryption occurs in a series of eight rounds. 

The algorithm uses six keys for every round (each key is 16 bits). Since IDEA completes eight rounds, it uses 48 subkeys in total. Additionally, its key schedule generates four extra keys for transforming the output in the last round. 

Other procedures relevant to this process are bitwise XOR, multiplication modulo, and addition modulo. 

Decryption process

The decryption of IDEA repeats similar steps as encryption. It does require different 16-bit key subblocks, which are the inverse versions of the encryption keys. Furthermore, the algorithm uses subblocks in reverse to decrypt data. 

Privacy is a BIG DEAL!


The beginning of the IDEA algorithm

IDEA emerged in 1991 thanks to the efforts of Xuejia Lai and James Massey. Its purpose was to replace DES (Data Encryption Standard).

IDEA started with a different name: Proposed Encryption Standard. Later, it was named the Improved Proposed Encryption Standard until finally becoming IDEA. 

While it did not replace DES, Pretty Good Privacy integrates IDEA into its operation. Thus, the algorithm is still in use, even if not for its intended purpose. 

How secure the IDEA algorithm is

The IDEA algorithm is secure, and most attacks do not threaten the reliability of IDEA in practice. In fact, most regard it as a robust encryption algorithm. So, some services could still use IDEA despite some of its shortcomings. However, providers choose other algorithms for multiple reasons. 

Problems with the IDEA algorithm 

You can find that many sources claim that AES largely replaced IDEA in today’s cryptography. Knowing that experts consider it relatively secure, it might seem odd that the algorithm is not in action anymore. 

Here are the biggest issues concerning IDEA and how they made the algorithm less practical and safe to use:

  • For a long time, IDEA creators patented the algorithm. Thus, it limited the adoption of this encryption option in certain countries. As of 2012, IDEA is patent-free, and anyone can use it. 
  • Due to its key size, IDEA lost some potential users. While 128-bit key size is secure, it is theoretically vulnerable to brute-force attacks. Of course, such attacks would require a significant amount of computing power. 
  • IDEA operates on 64-bit blocks, which might also be unsuitable for applications requiring larger blocks. For comparison, AES operates on 128-bit blocks.

IDEA NXT was also one of the attempts to improve the original algorithm. However, the patents might also interfere with its broader application. 

Choosing the best encryption methods 

You might have little control over what algorithms the systems you choose operate. However, you can pick products that opt for robust and modern solutions. 

Atlas VPN is one of the products that treats their users’ data security with the utmost care. We look for new methods and overcome challenges faced in the fast-paced world. Atlas VPN currently uses AES-256 encryption, one of the most secure algorithms!

Anton P.

Anton P.

Former chef and the head of Atlas VPN blog team. He's an experienced cybersecurity expert with a background of technical content writing.



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