view libtomcrypt/notes/tech0005.txt @ 1665:7c17995bcdfb

Improve address logging on early exit messages (#83) Change 'Early exit' and 'Exit before auth' messages to include the IP address & port as part of the message. This allows log scanning utilities such as 'fail2ban' to obtain the offending IP address as part of the failure event instead of extracting the PID from the message and then scanning the log again for match 'child connection from' messages Signed-off-by: Kevin Darbyshire-Bryant <[email protected]>
author Kevin Darbyshire-Bryant <6500011+ldir-EDB0@users.noreply.github.com>
date Wed, 18 Mar 2020 15:28:56 +0000
parents f849a5ca2efc
children
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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 -DLTC_RIJNDAEL -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?