In cryptography, XTEA (eXtended TEA) is a block cipher designed to correct
weaknesses in TEA. The cipher's designers were David Wheeler and Roger Needham
of the Cambridge Computer Laboratory, and the algorithm was presented in an
unpublished technical report in 1997 (Needham and Wheeler, 1997). It is not
subject to any patents.

Like TEA, XTEA is a 64-bit block Feistel cipher with a 128-bit key and a
suggested 64 Feistel rounds (i.e 32 cycles). Crypt::XTEA uses the recommended
value of 32 cycles by default.

This module implements XTEA encryption. It supports the Crypt::CBC interface.