TinyTwofish

; ------------------------------------------------------- ; Files: ; ; 2fish_avr.cfg ; Compile-time options/info (incl. key size) ; 2fish_avr.s ; Twofish encryption algorithm ; 2fish_c_avr.h ; 2fish_c_avr.s ; Wrapper for interfacing with C programs ; avrmacros.s ; Useful GNU as macros for the AVR ; example.s ; Test/demo program ; kat_test.s ; Known Answer Tests in AVR assembly ; kat_example.c ; Example/Known Answer Tests in C ; driver.c ; Simple AVR emulator using simavr ; ; Extra files: ; ; portable/2fishy.*, portable/2fishy_test.c ; Portable reference implementation (used during development) ; portable/2fish_x86_64.s ; x86-64 implementation (used during development) ; portable/KAT.txt ; Known-Answer-Tests from the original paper ; ; ------------------------------------------------------- ; Overview of most interesting implementations; KEY_SIZE=128 ; Column information: ; ; SIZE Actual footprint of code + tables (excl. alignment) ; ASIZE Minimum amount of flash necessary to load (incl. alignment) ; SRAM Total amount of SRAM needed (.bss and stack) ; E Cycles needed to encrypt one block ; KE Cycles needed to keyschedule & encrypt one block ; ; For a giving keysize, tinyTwofish runs in constant time; the timings ; listed are indepedent of the encryption key or the plaintext.

; Implementations not pre-computing the key-dependent s-box: ; Per SRAM size: ; ; 1) Smallest possible ; 2) Trade-off favouring space ; 3) Trade-off favouring speed ; 4) Fastest possible

SIZE: 724 ASIZE: 768 SRAM: 42 E: 83511 KE: 83891 ; INLINE_round_g=0 UNROLL_round_h=0 UNROLL_round_g=0 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=0 TAB_key=0 TAB_sbox=0 TAB_q=0 SRAM_q=1 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 1130 ASIZE: 1536 SRAM: 37 E: 17448 KE: 17828 ; INLINE_round_g=0 UNROLL_round_h=0 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=0 TAB_sbox=0 TAB_q=1 SRAM_q=0 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 1498 ASIZE: 1536 SRAM: 35 E: 12624 KE: 13004 ; INLINE_round_g=1 UNROLL_round_h=1 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=0 TAB_sbox=0 TAB_q=1 SRAM_q=0 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 2274 ASIZE: 2560 SRAM: 35 E: 11939 KE: 12319 ; INLINE_round_g=1 UNROLL_round_h=1 UNROLL_round_g=1 UNROLL_keypair=1 UNROLL_enc=1 UNROLL_swap=1 TAB_key=0 TAB_sbox=0 TAB_q=1 SRAM_q=0 UNROLL_whiten=1 INLINE_whiten=1

SIZE: 688 ASIZE: 704 SRAM: 179 E: 38006 KE: 83629 ; INLINE_round_g=0 UNROLL_round_h=0 UNROLL_round_g=0 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=0 TAB_key=1 TAB_sbox=0 TAB_q=0 SRAM_q=1 UNROLL_whiten=0 INLINE_whiten=0 SIZE: 1136 ASIZE: 1536 SRAM: 174 E: 7769 KE: 17332 ; INLINE_round_g=0 UNROLL_round_h=0 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=1 TAB_sbox=0 TAB_q=1 SRAM_q=0 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 1524 ASIZE: 1536 SRAM: 174 E: 5785 KE: 12929 ; INLINE_round_g=1 UNROLL_round_h=1 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=1 TAB_sbox=0 TAB_q=1 SRAM_q=0 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 2304 ASIZE: 2560 SRAM: 172 E: 5557 KE: 12321 ; INLINE_round_g=1 UNROLL_round_h=1 UNROLL_round_g=1 UNROLL_keypair=1 UNROLL_enc=1 UNROLL_swap=1 TAB_key=1 TAB_sbox=0 TAB_q=1 SRAM_q=0 UNROLL_whiten=1 INLINE_whiten=1

SIZE: 684 ASIZE: 704 SRAM: 691 E: 11894 KE: 24877 ; INLINE_round_g=0 UNROLL_round_h=0 UNROLL_round_g=0 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=0 TAB_key=1 TAB_sbox=0 TAB_q=1 SRAM_q=1 UNROLL_whiten=0 INLINE_whiten=0 SIZE: 762 ASIZE: 768 SRAM: 686 E: 7385 KE: 16468 ; INLINE_round_g=0 UNROLL_round_h=0 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=1 TAB_sbox=0 TAB_q=1 SRAM_q=1 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 1150 ASIZE: 1152 SRAM: 686 E: 5401 KE: 12065 ; INLINE_round_g=1 UNROLL_round_h=1 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=1 TAB_sbox=0 TAB_q=1 SRAM_q=1 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 1930 ASIZE: 1984 SRAM: 684 E: 5173 KE: 11457 ; INLINE_round_g=1 UNROLL_round_h=1 UNROLL_round_g=1 UNROLL_keypair=1 UNROLL_enc=1 UNROLL_swap=1 TAB_key=1 TAB_sbox=0 TAB_q=1 SRAM_q=1 UNROLL_whiten=1 INLINE_whiten=1

; Implementations using key-dependent S-Boxes (requires >1K SRAM) ; Per SRAM size: ; ; 1) Trade-off favouring space ; 2) Trade-off favouring speed ; 3) Fastest possible ; ; NOTE: ; - The 'smallest possible implementations' in this category perform worse but have larger Flash/SRAM footprints than some S-Box-less configurations ; - These implementations offer a SRAM vs. space/key setup time trade-off (TAB_q=0/1)

SIZE: 948 ASIZE: 960 SRAM: 1199 E: 4537 KE: 288237 ; INLINE_round_g=0 UNROLL_round_h=0 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=1 TAB_sbox=1 TAB_q=0 SRAM_q=1 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 1116 ASIZE: 1152 SRAM: 1198 E: 3801 KE: 285011 ; INLINE_round_g=1 UNROLL_round_h=0 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=1 TAB_sbox=1 TAB_q=0 SRAM_q=1 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 1554 ASIZE: 1600 SRAM: 1197 E: 3573 KE: 284783 ; INLINE_round_g=1 UNROLL_round_h=0 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=1 UNROLL_swap=1 TAB_key=1 TAB_sbox=1 TAB_q=0 SRAM_q=1 UNROLL_whiten=1 INLINE_whiten=1

SIZE: 1318 ASIZE: 1536 SRAM: 1198 E: 4537 KE: 50253 ; INLINE_round_g=0 UNROLL_round_h=0 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=1 TAB_sbox=1 TAB_q=1 SRAM_q=0 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 1514 ASIZE: 1536 SRAM: 1198 E: 3801 KE: 35779 ; INLINE_round_g=1 UNROLL_round_h=1 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=1 TAB_sbox=1 TAB_q=1 SRAM_q=0 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 2158 ASIZE: 2560 SRAM: 1196 E: 3573 KE: 35171 ; INLINE_round_g=1 UNROLL_round_h=1 UNROLL_round_g=1 UNROLL_keypair=1 UNROLL_enc=1 UNROLL_swap=1 TAB_key=1 TAB_sbox=1 TAB_q=1 SRAM_q=0 UNROLL_whiten=1 INLINE_whiten=1

SIZE: 944 ASIZE: 960 SRAM: 1710 E: 4537 KE: 46701 ; INLINE_round_g=0 UNROLL_round_h=0 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=1 TAB_sbox=1 TAB_q=1 SRAM_q=1 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 1140 ASIZE: 1152 SRAM: 1710 E: 3801 KE: 32227 ; INLINE_round_g=1 UNROLL_round_h=1 UNROLL_round_g=1 UNROLL_keypair=0 UNROLL_enc=0 UNROLL_swap=1 TAB_key=1 TAB_sbox=1 TAB_q=1 SRAM_q=1 UNROLL_whiten=1 INLINE_whiten=0 SIZE: 1784 ASIZE: 1792 SRAM: 1708 E: 3573 KE: 31619 ; INLINE_round_g=1 UNROLL_round_h=1 UNROLL_round_g=1 UNROLL_keypair=1 UNROLL_enc=1 UNROLL_swap=1 TAB_key=1 TAB_sbox=1 TAB_q=1 SRAM_q=1 UNROLL_whiten=1 INLINE_whiten=1

; A full list of all useful combinations of options is in config.txt. ; ; General recommendation: ; UNROLL_round_g = UNROLL_swap = UNROLL_whiten = 1, INLINE_whiten=0 ; Other settings result in unfavourable trade-offs. ; UNROLL_keypair = UNROLL_enc = 0 ; These control 'outer loops' which do not need to be unrolled. ; INLINE_round_g = UNROLL_round_h ; ; Increasing KEY_SIZE to 192 or 256 will increase SRAM size with 8/16 ; bytes if TAB_key=0; as well as increase ROM footprint. ; ; Certain configurations are sub-optimal, in the sense that they have no ; advantage over another configuration. These are omitted from config.txt. ; ; Range of supported MCU's: ; - tinyTwofish can run on ATtiny13 with KEY_SIZE=128 and KEY_SIZE=192 ; - ATmega32 and better (e.g. Arduino) can handle any configuration