This article summarizes publicly known attacks against block ciphers and stream ciphers. Note that there are perhaps attacks that are not publicly known, and not all entries may be up to date.
This column lists the complexity of the attack:
Attacks that lead to disclosure of the key or plaintext.
| Cipher | Security claim | Best attack | Publish date | Comment |
|---|---|---|---|---|
| AES128 | 2128 | 2126.1 time, 288 data, 28 memory | 2011-08-17 | Independent biclique attack.[1] |
| AES192 | 2192 | 2189.7 time, 280 data, 28 memory | ||
| AES256 | 2256 | 2254.4 time, 240 data, 28 memory | ||
| Blowfish | Up to 2448 | 4 of 16 rounds; 64-bit block is vulnerable to SWEET32 attack. | 2016 | Differential cryptanalysis.[2] Author of Blowfish (Bruce Schneier) recommends using Twofish instead.[3] SWEET32 attack demonstrated birthday attacks to recover plaintext with its 64-bit block size, vulnerable to protocols such as TLS, SSH, IPsec, and OpenVPN, without attacking the cipher itself.[4] |
| Twofish | 2128 – 2256 | 6 of 16 rounds (2256 time) | 1999-10-05 | Impossible differential attack.[5] |
| Serpent-128 | 2128 | 10 of 32 rounds (289 time, 2118 data) | 2002-02-04 | Linear cryptanalysis.[6] |
| Serpent-192 | 2192 | 11 of 32 rounds (2187 time, 2118 data) | ||
| Serpent-256 | 2256 | |||
| DES | 256 | 239 – 243 time, 243 known plaintexts | 2001 | Linear cryptanalysis.[7] In addition, broken by brute force in 256 time, no later than 1998-07-17, see EFF DES cracker.[8] Cracking hardware is available for purchase since 2006.[9] |
| Triple DES | 2168 | 2113 time, 232 data, 288 memory; 64-bit block is vulnerable to SWEET32 attack. | 2016 | Extension of the meet-in-the-middle attack. Time complexity is 2113 steps, but along with proposed techniques, it is estimated to be equivalent to 290 single DES encryption steps. The paper also proposes other time–memory tradeoffs.[10] SWEET32 attack demonstrated birthday attacks to recover plaintext with its 64-bit block size, vulnerable to protocols such as TLS, SSH, IPsec, and OpenVPN.[4] |
| KASUMI | 2128 | 232 time, 226 data, 230 memory, 4 related keys | 2010-01-10 | The cipher used in 3G cell phone networks. This attack takes less than two hours on a single PC, but isn't applicable to 3G due to known plaintext and related key requirements.[11] |
| RC4 | Up to 22048 | 220 time, 216.4 related keys (95% success probability) | 2007 | Commonly known as PTW attack, it can break WEP encryption in Wi-Fi on an ordinary computer in negligible time.[12] This is an improvement of the original Fluhrer, Mantin and Shamir attack published in 2001.[13] |
Attacks that allow distinguishing ciphertext from random data.
| Cipher | Security claim | Best attack | Publish date | Comment |
|---|---|---|---|---|
| RC4 | up to 22048 | ?? time, 230.6 bytes data (90% probability) | 2000 | Paper.[14] |
Attacks that lead to disclosure of the key.
| Cipher | Security claim | Best attack | Publish date | Comment |
|---|---|---|---|---|
| CAST (not CAST-128) | 264 | 248 time, 217 chosen plaintexts | 1997-11-11 | Related-key attack.[15] |
| CAST-128 | 2128 | 6 of 16 rounds (288.51 time, 253.96 data) | 2009-08-23 | Known-plaintext linear cryptanalysis.[16] |
| CAST-256 | 2256 | 24 of 48 rounds (2156.2 time, 2124.1 data) | ||
| IDEA | 2128 | 2126.1 time | 2012-04-15 | Narrow-biclique attack.[17] |
| MISTY1 | 2128 | 269.5 time, 264 chosen plaintexts | 2015-07-30 | Chosen-ciphertext, integral cryptanalysis,[18] an improvement over a previous chosen-plaintext attack.[19] |
| RC2 | 264 – 2128 | Unknown[clarification needed] time, 234 chosen plaintexts | 1997-11-11 | Related-key attack.[15] |
| RC5 | 2128 | Unknown | ||
| SEED | 2128 | Unknown | ||
| Skipjack | 280 | 280 | ECRYPT II recommendations note that, as of 2012, 80 bit ciphers provide only "Very short-term protection against agencies".[20] NIST recommends not to use Skipjack after 2010.[21] | |
| TEA | 2128 | 232 time, 223 chosen plaintexts | 1997-11-11 | Related-key attack.[15] |
| XTEA | 2128 | Unknown | ||
| XXTEA | 2128 | 259 chosen plaintexts | 2010-05-04 | Chosen-plaintext, differential cryptanalysis.[22] |
Attacks that allow distinguishing ciphertext from random data.
| Cipher | Security claim | Best attack | Publish date | Comment |
|---|---|---|---|---|
| CAST-256 | 2256 | 28 of 48 rounds (2246.9 time, 268 memory, 298.8 data) | 2012-12-04 | Multidimensional zero-correlation cryptanalysis.[23] |
On Wednesday, July 17, 1998 the EFF DES Cracker, which was built for less than $250,000, easily won RSA Laboratory's "DES Challenge II" contest and a $10,000 cash prize.
