Tiny Encryption Algorithm

:This article is about the TEA encryption algorithm. For other meanings, see TEA (disambiguation).

Properties

TEA operates on 64-bit blocks and uses a 128-bit key. It has a 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 constant are used to prevent simple attacks based on the symmetry of the rounds.

Related Topics:
Blocks - Key - Feistel structure - Key schedule - Magic constant - Symmetry

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TEA has a few weaknesses. Most notably, it suffers from equivalent keys — each key is equivalent to three others, and this means that the effective key size is only 126 bits (Kelsey et. al., 1996). This weakness led to a method for hacking Microsoft's Xbox game console, where the cipher was used as a hash function. TEA is also susceptible to a related-key attack which requires 223 chosen plaintexts under a related-key pair, with 232 time complexity (Kelsey et. al., 1997).

Related Topics:
Keys - Bit - Hacking - Microsoft - Xbox - Game console - Hash - Related-key attack - Chosen plaintext

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Because of these weaknesses, a number of revisions of TEA have been designed, including XTEA.

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Vikram Andem presents a comprehensive study of the cryptanalysis of the TEA (see below).

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