What is 3DES? How Triple Data Encryption Standard Works

Modern encryption standards are dominated by algorithms like AES, yet older ciphers still operate within legacy infrastructure across financial services, healthcare, and industrial systems. Triple Data Encryption Standard (3DES) remains in use in environments such as ATM networks, payment terminals, and embedded devices that depend on long-standing cryptographic implementations. Although 3DES was designed to extend the security of DES, it no longer meets modern security requirements. NIST has deprecated 3DES and disallowed its use for encryption after 2023 under NIST SP 800-67 Rev. 2, permitting it only in limited legacy scenarios. Understanding how 3DES works, where it still exists, and its limitations is essential for teams managing transitional systems. This article explains what 3DES is, how Triple DES works at a technical level and where it is still used today. What is 3DES? The Triple Data Encryption Standard, or 3DES, is a symmetric-key block cipher that encrypts data by applying the original DES algorithm three times to each 64-bit block. TDES processes the data in sizes of 64 bits and requires shared secret keys to be used. Why was 3DES Created? 3DES was introduced when DES’s 56-bit key became demonstrably vulnerable to brute-force attacks. Instead of replacing DES outright, 3DES […]