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Cipher security summary
Summary of attacks against common ciphers

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.

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Table color key

  No known successful attacks — attack only breaks a reduced version of the cipher   Theoretical break — attack breaks all rounds and has lower complexity than security claim   Attack demonstrated in practice

Best attack

This column lists the complexity of the attack:

  • If the attack doesn't break the full cipher, "rounds" refers to how many rounds were broken
  • "time" — time complexity, number of cipher evaluations for the attacker
  • "data" — required known plaintext-ciphertext pairs (if applicable)
  • "memory" — how many blocks worth of data needs to be stored (if applicable)
  • "related keys" — for related-key attacks, how many related key queries are needed

Common ciphers

Key or plaintext recovery attacks

Attacks that lead to disclosure of the key or plaintext.

CipherSecurity claimBest attackPublish dateComment
AES1282128 2126.1 time, 288 data, 28 memory 2011-08-17Independent biclique attack.1
AES1922192 2189.7 time, 280 data, 28 memory
AES2562256 2254.4 time, 240 data, 28 memory
BlowfishUp to 24484 of 16 rounds; 64-bit block is vulnerable to SWEET32 attack.2016Differential 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
Twofish2128 – 22566 of 16 rounds (2256 time)1999-10-05Impossible differential attack.5
Serpent-128212810 of 32 rounds (289 time, 2118 data)2002-02-04Linear cryptanalysis.6
Serpent-192219211 of 32 rounds (2187 time, 2118 data)
Serpent-2562256
DES256239 – 243 time, 243 known plaintexts2001Linear 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 21682113 time, 232 data, 288 memory; 64-bit block is vulnerable to SWEET32 attack.2016Extension 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.11
KASUMI2128232 time, 226 data, 230 memory, 4 related keys2010-01-10The 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.12
RC4Up to 22048220 time, 216.4 related keys (95% success probability)2007Commonly known as PTW attack, it can break WEP encryption in Wi-Fi on an ordinary computer in negligible time.13 This is an improvement of the original Fluhrer, Mantin and Shamir attack published in 2001.14

Distinguishing attacks

Main article: Distinguishing attack

Attacks that allow distinguishing ciphertext from random data.

CipherSecurity claimBest attackPublish dateComment
RC4up to 22048?? time, 230.6 bytes data (90% probability)2000Paper.15

Less-common ciphers

Key recovery attacks

Attacks that lead to disclosure of the key.

CipherSecurity claimBest attackPublish dateComment
CAST (not CAST-128)264248 time, 217 chosen plaintexts1997-11-11Related-key attack.16
CAST-12821286 of 16 rounds (288.51 time, 253.96 data)2009-08-23Known-plaintext linear cryptanalysis.17
CAST-256225624 of 48 rounds (2156.2 time, 2124.1 data)
IDEA2128 2126.1 time2012-04-15Narrow-biclique attack.18
MISTY12128 269.5 time, 264 chosen plaintexts 2015-07-30Chosen-ciphertext, integral cryptanalysis,19 an improvement over a previous chosen-plaintext attack.20
RC2264 – 2128Unknown time, 234 chosen plaintexts1997-11-11Related-key attack.21
RC52128Un­known
SEED2128Un­known
Skipjack280280ECRYPT II recommendations note that, as of 2012, 80 bit ciphers provide only "Very short-term protection against agencies".22 NIST recommends not to use Skipjack after 2010.23
TEA2128 232 time, 223 chosen plaintexts 1997-11-11Related-key attack.24
XTEA2128Un­known
XXTEA2128259 chosen plaintexts2010-05-04Chosen-plaintext, differential cryptanalysis.25

Distinguishing attacks

Main article: Distinguishing attack

Attacks that allow distinguishing ciphertext from random data.

CipherSecurity claimBest attackPublish dateComment
CAST-2562256 28 of 48 rounds (2246.9 time, 268 memory, 298.8 data) 2012-12-04Multidimensional zero-correlation cryptanalysis.26

See also

References

  1. Andrey Bogdanov; Dmitry Khovratovich; Christian Rechberger (2011-08-17). "Biclique Cryptanalysis of the Full AES". Cryptology ePrint Archive. https://eprint.iacr.org/2011/449 ↩

  2. Vincent Rijmen (1997). "Cryptanalysis and Design of Iterated Block Ciphers". Ph.D. Thesis. /wiki/Vincent_Rijmen ↩

  3. Dahna McConnachie (2007-12-27). "Bruce Almighty: Schneier preaches security to Linux faithful". Computerworld. Archived from the original on 2012-06-03. Retrieved 2014-02-13. https://web.archive.org/web/20120603124940/http://www.computerworld.com.au/article/46254/bruce_almighty_schneier_preaches_security_linux_faithful/ ↩

  4. Karthikeyan Bhargavan, Gaëtan Leurent (August 2016). "On the Practical (In-)Security of 64-bit Block Ciphers — Collision Attacks on HTTP over TLS and OpenVPN". ACM CCS 2016. https://sweet32.info/ ↩

  5. Niels Ferguson (1999-10-05). "Impossible Differentials in Twofish". Schneier. /wiki/Niels_Ferguson ↩

  6. Eli Biham; Orr Dunkelman; Nathan Keller (2002-02-04). Linear Cryptanalysis of Reduced Round Serpent. FSE 2002. doi:10.1007/3-540-45473-X_2. /wiki/Doi_(identifier) ↩

  7. Junod, Pascal (2001). On the Complexity of Matsui's Attack. Selected Areas in Cryptography. pp. 199–211. Archived from the original on 2009-05-27. https://web.archive.org/web/20090527065754/http://crypto.junod.info/sac01.html ↩

  8. "DES Cracker Project". EFF. Archived from the original on May 7, 2017. Retrieved August 26, 2015. 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. https://web.archive.org/web/20170507231657/https://w2.eff.org/Privacy/Crypto/Crypto_misc/DESCracker/HTML/19980716_eff_des_faq.html ↩

  9. "COPACOBANA – Special-Purpose Hardware for Code-Breaking". http://www.sciengines.com/copacobana ↩

  10. Stefan Lucks (1998-03-23). "Attacking Triple Encryption". Fast Software Encryption. Lecture Notes in Computer Science. Vol. 1372. Springer. pp. 239–253. doi:10.1007/3-540-69710-1_16. ISBN 978-3-540-64265-7. 978-3-540-64265-7 ↩

  11. Karthikeyan Bhargavan, Gaëtan Leurent (August 2016). "On the Practical (In-)Security of 64-bit Block Ciphers — Collision Attacks on HTTP over TLS and OpenVPN". ACM CCS 2016. https://sweet32.info/ ↩

  12. Orr Dunkelman; Nathan Keller; Adi Shamir (2010-01-10). "A Practical-Time Attack on the A5/3 Cryptosystem Used in Third Generation GSM Telephony". Cryptology ePrint Archive. https://eprint.iacr.org/2010/013 ↩

  13. Erik Tews; Ralf-Philipp Weinmann; Andrei Pyshkin (2007). Breaking 104 Bit WEP in Less Than 60 Seconds. WISA 2007. https://eprint.iacr.org/2007/120 ↩

  14. Scott Fluhrer; Itsik Mantin; Adi Shamir (2001-12-20). Weaknesses in the Key Scheduling Algorithm of RC4 (PDF). Selected Areas in Cryptography 2001. http://www.crypto.com/papers/others/rc4_ksaproc.pdf ↩

  15. Scott R. Fluhrer; David A. McGrew. Statistical Analysis of the Alleged RC4 Keystream Generator (PDF). FSE 2000. pp. 19–30. Archived from the original (PDF) on 2014-05-02. https://web.archive.org/web/20140502020708/http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/FluhrerMcgrew.pdf ↩

  16. John Kelsey; Bruce Schneier; David Wagner (1997-11-11). "Related-key cryptanalysis of 3-WAY, Biham-DES, CAST, DES-X NewDES, RC2, and TEA". In Yongfei Han; Tatsuaki Okamoto; Sihan Quing (eds.). Information and Communications Security: First International Conference. Vol. 1334. Springer. pp. 233–246. CiteSeerX 10.1.1.35.8112. doi:10.1007/BFb0028479. ISBN 978-3-540-63696-0. 978-3-540-63696-0 ↩

  17. Meiqin Wang; Xiaoyun Wang; Changhui Hu (2009-08-23). "New Linear Cryptanalytic Results of Reduced-Round of CAST-128 and CAST-256". Selected Areas in Cryptography. Lecture Notes in Computer Science. Vol. 5381. pp. 429–441. doi:10.1007/978-3-642-04159-4_28. ISBN 978-3-642-04158-7. S2CID 35612393. 978-3-642-04158-7 ↩

  18. Dmitry Khovratovich; Gaetan Leurent; Christian Rechberger. "Narrow-Bicliques: Cryptanalysis of Full IDEA" (PDF). Archived from the original (PDF) on 2013-12-03. Retrieved 2015-08-26. https://web.archive.org/web/20131203001223/http://www.di.ens.fr/~leurent/files/IDEA_EC12.pdf ↩

  19. Achiya Bar-On (2015-07-30). "A 270 Attack on the Full MISTY1". Cryptology ePrint Archive. https://eprint.iacr.org/2015/746 ↩

  20. Yosuke Todo (2015-07-06). Integral Cryptanalysis on Full MISTY1. CRYPTO 2015. https://eprint.iacr.org/2015/682 ↩

  21. John Kelsey; Bruce Schneier; David Wagner (1997-11-11). "Related-key cryptanalysis of 3-WAY, Biham-DES, CAST, DES-X NewDES, RC2, and TEA". In Yongfei Han; Tatsuaki Okamoto; Sihan Quing (eds.). Information and Communications Security: First International Conference. Vol. 1334. Springer. pp. 233–246. CiteSeerX 10.1.1.35.8112. doi:10.1007/BFb0028479. ISBN 978-3-540-63696-0. 978-3-540-63696-0 ↩

  22. "ECRYPT II Yearly Report on Algorithms and Keysizes (2011-2012)" (PDF). CORDIS. 30 September 2012. D.SPA.20 Rev. 1.0, ICT-2007-216676 ECRYPT II. https://cordis.europa.eu/docs/projects/cnect/6/216676/080/deliverables/002-DSPA20.pdf ↩

  23. Transitions: Recommendation for Transitioning the Use of Cryptographic Algorithms and Key Lengths, NIST http://csrc.nist.gov/publications/nistpubs/800-131A/sp800-131A.pdf ↩

  24. John Kelsey; Bruce Schneier; David Wagner (1997-11-11). "Related-key cryptanalysis of 3-WAY, Biham-DES, CAST, DES-X NewDES, RC2, and TEA". In Yongfei Han; Tatsuaki Okamoto; Sihan Quing (eds.). Information and Communications Security: First International Conference. Vol. 1334. Springer. pp. 233–246. CiteSeerX 10.1.1.35.8112. doi:10.1007/BFb0028479. ISBN 978-3-540-63696-0. 978-3-540-63696-0 ↩

  25. Elias Yarrkov (2010-05-04). "Cryptanalysis of XXTEA". Cryptology ePrint Archive. https://eprint.iacr.org/2010/254 ↩

  26. Andrey Bogdanov; Gregor Leander; Kaisa Nyberg; Meiqin Wang (2012-12-04). "Integral and multidimensional linear distinguishers with correlation zero" (PDF). Advances in Cryptology – ASIACRYPT 2012: 18th International Conference on the Theory and Application of Cryptology and Information Security. Vol. 7658. Springer. pp. 244–261. doi:10.1007/978-3-642-34961-4. ISBN 978-3-642-34960-7. S2CID 26601027. 978-3-642-34960-7 ↩