view libtomcrypt/notes/tech0005.txt @ 1629:258b57b208ae

Fix for issue successfull login of disabled user (#78) This commit introduces fix for scenario: 1. Root login disabled on dropbear 2. PAM authentication model enabled While login as root user, after prompt for password user is being notified about login failrue, but after second attempt of prompt for password within same session, login becames succesfull. Signed-off-by: Pawel Rapkiewicz <[email protected]>
author vincentto13 <33652988+vincentto13@users.noreply.github.com>
date Wed, 20 Mar 2019 15:03:40 +0100
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?