Mercurial > dropbear
view libtomcrypt/notes/tech0005.txt @ 958:1bf92da7a2a0
Try without identifying current user
Small change that warns the user if the current user cannot be identified rather than aborting. This came in handy when I put dropbear on a dlink that did not have a true user environment. Falling back on the "-l" option and user@ options works just fine as a client. The only implication I found is that the -J option will fail ungracefully without a known own_user.
| author | iquaba <cooka2011@gmail.com> |
|---|---|
| date | Wed, 06 Aug 2014 08:48:43 -0500 |
| parents | 0cbe8f6dbf9e |
| children | f849a5ca2efc |
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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?