1 Tech Note 0005 2 Minimizing Code Space 3 Tom St Denis 4 5 Introduction 6 ------------ 7 8 Tweaking... 9 10 You can disable whole classes of algorithms on the command line with the LTC_NO_* defines. From there you can manually turn on what you want to enable. 11 12 The following build with GCC 3.4.4 on an AMD64 box gets you AES, CTR mode, SHA-256, HMAC, Yarrow, full RSA PKCS #1, PKCS #5 and ASN.1 DER in 13 roughly 40KB of code (49KB on the ARMv4) (both excluding the math library). 14 15 CFLAGS="-DLTC_NO_CIPHERS -DLTC_NO_HASHES -DLTC_NO_PRNGS -DLTC_NO_MACS -DLTC_NO_MODES -DLTC_NO_PK -DRIJNDAEL -DLTC_CTR_MODE -DSHA256 \ 16 -DLTC_HMAC -DYARROW -DMRSA -DMPI -DTFM_DESC -DARGTYPE=3 -Os -DLTC_SMALL_CODE -fomit-frame-pointer" make IGNORE_SPEED=1 17 18 Obviously this won't get you performance but if you need to pack a crypto lib in a device with limited means it's more than enough... 19 20 Neato eh? 21
