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annotate libtomcrypt/notes/tech0005.txt @ 1397:18c0b0e450ff

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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
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children f849a5ca2efc
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1 Tech Note 0005
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2 Minimizing Code Space
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3 Tom St Denis
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5 Introduction
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6 ------------
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8 Tweaking...
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10 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.
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12 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
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13 roughly 40KB of code (49KB on the ARMv4) (both excluding the math library).
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15 CFLAGS="-DLTC_NO_CIPHERS -DLTC_NO_HASHES -DLTC_NO_PRNGS -DLTC_NO_MACS -DLTC_NO_MODES -DLTC_NO_PK -DRIJNDAEL -DLTC_CTR_MODE -DSHA256 \
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16 -DLTC_HMAC -DYARROW -DMRSA -DMPI -DTFM_DESC -DARGTYPE=3 -Os -DLTC_SMALL_CODE -fomit-frame-pointer" make IGNORE_SPEED=1
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18 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...
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20 Neato eh?