Mercurial > dropbear
view libtomcrypt/notes/tech0005.txt @ 511:582cb38e4eb5 insecure-nocrypto
propagate from branch 'au.asn.ucc.matt.dropbear' (head cdcc3c729e29544e8b98a408e2dc60e4483dfd2a)
to branch 'au.asn.ucc.matt.dropbear.insecure-nocrypto' (head 0ca38a1cf349f7426ac9de34ebe4c3e3735effab)
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Thu, 06 Nov 2008 13:16:55 +0000 |
| parents | 0cbe8f6dbf9e |
| children | f849a5ca2efc |
line wrap: on
line source
Tech Note 0005 Minimizing Code Space Tom St Denis Introduction ------------ Tweaking... 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. 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 roughly 40KB of code (49KB on the ARMv4) (both excluding the math library). CFLAGS="-DLTC_NO_CIPHERS -DLTC_NO_HASHES -DLTC_NO_PRNGS -DLTC_NO_MACS -DLTC_NO_MODES -DLTC_NO_PK -DRIJNDAEL -DLTC_CTR_MODE -DSHA256 \ -DLTC_HMAC -DYARROW -DMRSA -DMPI -DTFM_DESC -DARGTYPE=3 -Os -DLTC_SMALL_CODE -fomit-frame-pointer" make IGNORE_SPEED=1 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... Neato eh?