Mercurial > dropbear
view libtomcrypt/notes/tech0005.txt @ 1397:18c0b0e450ff
Fix configure options using AC_ARG_ENABLE
Configure options to disable some features, which are checked using
AC_ARG_ENABLE can be invoked with --enable-<option> as well.
The current configure script always generates a #define for such options
even though the --enable-<option> case should not generate a #define.
Fix this by properly checking if the feature should be enabled, in which
case no #define is being generated.
Signed-off-by: Stefan Hauser <[email protected]>
| author | Stefan Hauser <stefan@shauser.net> |
|---|---|
| date | Wed, 27 Jul 2016 19:38:56 +0200 |
| 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?