Mercurial > dropbear

annotate libtomcrypt/notes/tech0005.txt @ 1156:a8f4dade70e5

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avoid getpass when not used some systems (like android's bionic) do not provide getpass. you can disable ENABLE_CLI_PASSWORD_AUTH & ENABLE_CLI_INTERACT_AUTH to avoid its use (and rely on pubkey auth), but the link still fails because the support file calls getpass. do not define this func if both of those auth methods are not used.
author Mike Frysinger <vapier@gentoo.org>
date Wed, 21 Oct 2015 22:39:55 +0800
parents 0cbe8f6dbf9e
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?