Editing Tiny Encryption Algorithm (section)

==Properties==

TEA operates on two 32-bit [[unsigned integers]] (could be derived from a 64-bit data [[block size (cryptography)|block]]) and uses a 128-bit  [[key (cryptography)|key]]. It has a [[Feistel network|Feistel structure]] with a suggested 64 rounds, typically implemented in pairs termed ''cycles''. It has an extremely simple [[key schedule]], mixing all of the key material in exactly the same way for each cycle. Different multiples of a [[magic number (programming)|magic constant]] are used to prevent simple attacks based on the [[symmetry]] of the rounds. The magic constant, 2654435769 or 0x9E3779B9 is chosen to be {{math|⌊2{{sup|32}}{{fraction}}{{phi}}⌋}}, where {{math|{{phi}}}} is the [[golden ratio]] (as a [[nothing-up-my-sleeve number]]).<ref name="teapaper"/>

TEA has a few weaknesses. Most notably, it suffers from equivalent keys—each key is equivalent to three others, which means that the effective key size is only 126 [[bit]]s.<ref name="kelsey1996">{{cite book |first1=John |last1=Kelsey |last2=Schneier |first2=Bruce |author-link2=Bruce Schneier |last3=Wagner |first3=David |title=Advances in Cryptology — CRYPTO '96 |chapter=Key-Schedule Cryptanalysis of IDEA, G-DES, GOST, SAFER, and Triple-DES |series=Lecture Notes in Computer Science |url=http://www.schneier.com/paper-key-schedule.pdf |volume=1109 |pages=237–251 |year=1996 |doi=10.1007/3-540-68697-5_19 |isbn=978-3-540-61512-5 |access-date=25 February 2008 |archive-date=8 February 2012 |archive-url=https://web.archive.org/web/20120208081900/http://www.schneier.com/paper-key-schedule.pdf |url-status=dead }}</ref> As a result, TEA is especially bad as a [[cryptographic hash function]]. This weakness led to a method for [[Hacker (hobbyist)|hacking]] [[Microsoft]]'s [[Xbox (console)|Xbox]] [[game console]], where the cipher was used as a hash function.<ref>{{cite web |url=http://www.xbox-linux.org/wiki/17_Mistakes_Microsoft_Made_in_the_Xbox_Security_System#Startup_Security.2C_Take_Two |title=17 Mistakes Microsoft Made in the Xbox Security System |author=Michael Steil |archive-url=https://web.archive.org/web/20090416175601/http://www.xbox-linux.org/wiki/17_Mistakes_Microsoft_Made_in_the_Xbox_Security_System |archive-date=16 April 2009}}</ref> TEA is also susceptible to a [[related-key attack]] which requires 2<sup>23</sup> [[chosen plaintext]]s under a related-key pair, with 2<sup>32</sup> time complexity.<ref name="kelsey1997">{{cite book |first1=John |last1=Kelsey |last2=Schneier |first2=Bruce |author-link2=Bruce Schneier |last3=Wagner |first3=David |title=Information and Communications Security |chapter=Related-key cryptanalysis of 3-WAY, Biham-DES, CAST, DES-X, NewDES, RC2, and TEA |series=Lecture Notes in Computer Science | 
url = http://www.schneier.com/paper-relatedkey.html | 
volume = 1334 | pages = 233–246 | year = 1997 | 
doi = 10.1007/BFb0028479| 
isbn = 978-3-540-63696-0 | 
citeseerx = 10.1.1.35.8112 }}</ref>  Because of these weaknesses, the [[XTEA]] cipher was designed.