> there is an attack that effectively limits it to twice the effective bits of DES
* Meet-in-the-Middle attack.
https://en.wikipedia.org/wiki/Meet-in-the-middle_attack
This attack is surprisingly simple, if you encrypt the message twice by
ciphertext = encrypt(encrypt(message, key1), key2)
Then,
decrypt(ciphertext, key2) == encrypt(message, key1)
An important security property all symmetric ciphers should offer is immunity to chosen-plaintext attack, if the attacker controls "message", it shouldn't make the cipher more easy to crack.
But in this case, the attacker can obtain all the 2^56 possible encryption of message by enumerating key1, put it in a lookup table (assume the table-lookup time is O(1)) , then we can try all possible decryption of ciphertext by enumerating key2. Then compare it with the lookup-table for a match, bingo!
If key is 56-bit, the attacker gets 2^56 outputs for the left side, 2^56 outputs for the right side, total number of operations is 2 x 2^56 == 2^57, not 2^112.
To increase the security claim to 2^112, we need triple encryption, not double encryption, thus 2DES is never used.
The idea that simple double-encryption doesn't work because of such a simple attack shocked a lot of newcomers.
FAQs
Our results show that 80-bit security can be attacked by distributed GPU clusters. Thus, we recommend Present with 80-bit key and other cryptographic algorithms with 80-bit or shorter keys to be removed from ISO/IEC and other standards. 112-bit security of 3des can be broken in 8 years with RTX 3070 GPUs.
Can Triple DES be cracked? ›
3DES is about 2^56 times as difficult to crack as DES. (Not 2^112 times because there is an attack that effectively limits it to twice the effective bits of DES, rather than the three times you might expect at first). If you're using 3 different keys, yes, that makes sense.
How long does it take to crack 56-bit DES? ›
The original Data Encryption Standard (DES) developed in the 70s only had a 56-bit key. In today's world, some computers could crack this in less than 400 seconds, but the 128-bit would take a practical infinity of years to break.
Is 3DES breakable? ›
3DES is not truly “broken,” since there are no feasible ways to deterministically crack the cipher, but it remains vulnerable to a type of probabilistic attack known as Sweet32 – a type of Birthday Attack that depends on randomly occurring coincidences like meeting someone with the same birthday as yours.
How long is a Triple DES bit? ›
When Triple DES is used with three independent keys, sometimes referred to as 3TDEA, it has a key length of 168 bits (3 x 56-bit DES keys = 168 independent key bits). Due to meet-in-the-middle attacks, however, the effective security 3TDEA provides is only 112 bits.
What is the DES and 3DES algorithm? ›
In cryptography, Triple DES (3DES or TDES), officially the Triple Data Encryption Algorithm (TDEA or Triple DEA), is a symmetric-key block cipher, which applies the DES cipher algorithm three times to each data block.
Can DES encryption be broken? ›
There are three attacks known that can break the full 16 rounds of DES with less complexity than a brute-force search: differential cryptanalysis (DC), linear cryptanalysis (LC), and Davies' attack.
How did 3DES improve on DES? ›
Triple DES (3DES) represents a significant advancement in the field of cryptography by addressing the vulnerabilities of single and double encryption methods. Through its use of three stages of DES encryption and decryption, 3DES effectively increases the key length and resists meet-in-the-middle attacks.
What is the disadvantage of 3DES? ›
Limitations of 3DES
Slow Speed: The triple-layered encryption process of 3DES makes it slower than other encryption algorithms. Limited Key Size Options: While 3DES supports variable key sizes, the maximum key size is only 192 bits, which may not be enough to meet the security needs of some applications.
How long would it take a supercomputer to crack AES-256? ›
AES-256 encryption is virtually uncrackable using any brute-force method. It would take millions of years to break it using the current computing technology and capabilities. However, no encryption standard or system is completely secure. In 2009, a cryptanalysis discovered a possible related-key attack.
The EE Times points out that even using a supercomputer, a “brute force” attack would take one billion years to crack AES 128-bit encryption.
How easy is it to crack AES 128? ›
With the right quantum computer, AES-128 would take about 2.61*10^12 years to crack, while AES-256 would take 2.29*10^32 years. For reference, the universe is currently about 1.38×10^10 years old, so cracking AES-128 with a quantum computer would take about 200 times longer than the universe has existed.
Is 3DES still used today? ›
The Triple Data Encryption Algorithm (TDEA or 3DES) is being officially decommissioned, according to draught guidelines provided by NIST on July 19, 2018.
What replaced 3DES? ›
The Advanced Encryption Standard (AES) has changed older encryption techniques like DES, 3DES, and TDEA because of its superior security, performance, and sturdy design. AES gives longer key lengths, making it more proof against attacks, and methods data more effectively.
How big is a des3 key? ›
The triple-DES key length contains 168 bits but the key security falls to 112 bits. Triple DES encrypts input data three times. The three keys are referred to as k1, k2, and k3.
Is 3DES still considered secure? ›
About Triple DES or 3DES
Three-key TDEA may continue to be used for encryption in existing applications but shall not be used for encryption in new applications. After December 31, 2023, three-key TDEA is disallowed for encryption unless specifically allowed by other NIST guidance.
Is Triple DES faster than AES? ›
3DES (Triple Data Encryption Standard) algorithm
This method is gradually being replaced by the AES, since it is up to six times faster, however, there are still electronic payments, credit cards, etc. that use the 3DES standard, so it is still quite in force.
What is the seed length for 3DES? ›
What is the Seed length (seedlen) length for 3DES? Explanation: Seed length = Output Block Length + Key Length = 64 + 232.
