Encrypted file transfer in a solution like Cerberus FTP Server is simple to implement, but with a number of encryption and cipher options available, it can be helpful to understand exactly how your data is secured. Today, we’ll review the Advanced Encryption Standard (AES) to better understand how encrypted file transfer works.

How does encrypted file transfer work?


Data encryption uses a mathematical computation to generate two components: 

  • A cipher, an algorithm that takes a plaintext input and renders it into a coded ciphertext that is not human readable 
  • A matching key, which is used to decode the ciphertext back into plaintext

Ciphers and keys are generated by taking a defined array of binary data (or bits) and performing a series of computations on that data in order to generate a uniquely matching pair. The more computations that are performed, the more potential ciphers and keys are generated, which makes attempts at “guessing” the keys by brute force computation virtually impossible. 

A number of encryption standards exist, but among the most common is the Advanced Encryption Standard (AES).


What is AES 256 Encryption?


AES encryption is one of the most commonly adopted secure data transmission standards. The U.S. National Institute of Standards and Technology chose AES encryption as the U.S. federal government’s encryption standard in the early 2000s to replace the prior Data Encryption Standard (DES) as advances in computing power showed that the DES was vulnerable to brute force “guessing” of ciphers and keys.

AES encryption can be generated in several key sizes, ranging from 128- to 256-bit keys, depending on how many computational rounds are performed during encryption. AES 256 is currently the “highest” encryption level and is produced by 14 computational rounds. As a result, experts estimate that trying to recreate an AES 256 key pair using current computing methods and power would take millions of years to accomplish. 

How Does AES 256 Encryption Work?

AES 256 encryption works through the following steps:

  1. Information Blocking: AES begins by separating binary data into blocks of 128 bits (16 bytes). If the data is not a multiple of 16 bytes, padding is added to make it fit into complete blocks.
  2. Key Expansion: The AES encryption algorithm then uses a process called vital expansion to generate a set of “round keys” based on the original cipher encryption key that will unlock each subsequent computation pass. These “round keys” are used in both the encryption and decryption process.
  3. Initial Round: The first round of AES encryption performs an XOR operation between the input data and the first round key to begin masking the data.
  4. Subsequent Rounds: Each subsequent round performs a number of operations that further replace, shift, and mix the original data in the starting array, using the round key to ensure security.
  5. Final Round: The final round of AES encryption operates similarly to step 4, but performs slightly less complex operations to improve algorithm performance
  6. Cipher Output: After all the rounds are completed, the resulting cipher is the encrypted form of the original data.

To decrypt the cipher and retrieve the original data, an AES keyholder uses its decryption key, which is derived from the original encryption key, to follow the same steps in reverse order. 

Scale Enterprise File Transfers With JSCAPE, Part of the Redwood Software Ecosystem

For a deeper dive into secure file transfer protocols beyond AES, including comparisons and detailed guides on implementing robust security measures, JSCAPE, a Redwood Software brand alongside Cerberus, offers extensive insights and expertise. Explore the differences and applications of DSA vs. RSA encryption to optimize your file transfers for security and performance. Read more on JSCAPE’s blog: DSA vs. RSA Encryption – Which Works Best for File Transfers?

How Does Cerberus FTP Server Implement AES 256 Encryption?

Cerberus FTP Server’s SFTP transfer protocol supports several encryption techniques, including AES. A full list of these ciphers and key exchange methods appears on our support page, and these encryption settings can be managed from your server’s security settings page

You can download a trial version at this link if you want to explore encrypted file transfer with Cerberus FTP.