tinycrypt/block/tea

 [ TEA Block cipher





Designers         Roger Needham, David Wheeler


First published   1994


Successors        XTEA


Key sizes         128 bits


Block sizes       64 bits


Structure         Feistel network


Rounds            variable; recommended 64 Feistel rounds (32 cycles)








 [ XTEA Block cipher





Designers         Roger Needham, David Wheeler


First published   1997


Derived from      TEA


Successors        Corrected Block TEA


Key sizes         128 bits


Block sizes       64 bits


Structure         Feistel cipher


Rounds            variable; recommended 64 Feistel rounds (32 cycles)








 [ XXTEA Block cipher


 


Designers         David Wheeler, Roger Needham


First published   1998


Derived from      Block TEA


Key sizes         128 bits


Block sizes       arbitrary, at least two words (64 bits)


Structure         Unbalanced Feistel Network


Rounds            depends on the block size; ~52+6*words (6-32 full cycles)








TEA in x86 assembly





I've tried to verify the correctness of the algorithm and ran into problems with test


vectors taken off the internet from various random sources.





To my knowledge, the implementation here is fine.





tea.c          - reference and my own implementation of encrypt/decrypt functions.


test.c         - simple unit to test tea.c





tea_crypt1.asm - 2 separate functions in x86 assembly


tea_crypt2.asm - 2 separate functions in x86 assembly that use carry flag for looping


tea_crypt3.asm - 1 function that uses carry flag and jmp operation for encrypt/decrypt


tea_crypt.asm  - 1 function that uses carry flag and negate operation for ADD/SUB