Cipher security summary

Template:Use ymd dates This article summarizes publicly known attacks against block ciphers. Note that not all entries may be up to date.

Table color key
No known successful attacks
Theoretical break
Attack demonstrated in practice

The Best attack 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 block ciphers[]

Attacks that lead to disclosure of the key.

Cipher	Security claim	Best attack	Attack date	Comment
AES128	2¹²⁸	Template:?
AES192	2¹⁹²	Template:Nowrap	2009-12-04^[1]
AES256	2²⁵⁶	Template:Nowrap	2009-12-04^[1]
Blowfish	2⁴⁴⁸	4 of 16 rounds	1997^[2]
DES	2⁵⁶	2⁵⁶ time	1998-07-17^[3]	Broken by brute force, see EFF DES cracker. Off-the-shelf hardware is available for $10,000.^[4]
Template:Nowrap	2¹⁶⁸	2¹¹³ time, 2³² data, 2⁸⁸ memory	1998-03-23^[5]
KASUMI	2¹²⁸	2³² time, 2²⁶ data, 2³⁰ memory, 4 related keys	2010-01-10^[6]	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.
Serpent-128	2¹²⁸	10 of 32 rounds (2⁸⁹ time, 2¹¹⁸ data)	2002-02-04^[7]	Linear cryptanalysis
Serpent-192	2¹⁹²	11 of 32 rounds (2¹⁸⁷ time, 2¹¹⁸ data)
Serpent-256	2²⁵⁶	11 of 32 rounds (2¹⁸⁷ time, 2¹¹⁸ data)
Twofish	2¹²⁸..2²⁵⁶	6 of 16 rounds (2²⁵⁶ time)	1999-10-05^[8]

Attacks that lead to disclosure of the key.

Cipher	Security claim	Best attack	Attack date	Comment
CAST-128	2¹²⁸	2⁴⁸ time, 2¹⁷ chosen plaintexts	1997-11-11^[9]	Related-key attack
IDEA	2¹²⁸	6 of 8.5 rounds (2^126.8 time, 2⁶⁴ data)	2007-03-26^[10]	Differential-linear attack
RC2	2⁶⁴..2¹²⁸	2^?? time, 2³⁴ chosen plaintexts	1997-11-11^[9]	Related-key attack
RC5	2¹²⁸	Template:?
SEED	2¹²⁸	Template:?
Skipjack	2⁸⁰	Template:Nowrap	1999-05-02^[11]	Chosen plaintext impossible differential cryptanalysis
TEA	2¹²⁸	Template:Nowrap	1997-11-11^[9]	Related-key attack
XTEA	2¹²⁸	Template:?
XXTEA	2¹²⁸	2⁵⁹ chosen plaintexts	2010-05-04^[12]	Chosen-plaintext, differential cryptanalysis