Mercurial > dropbear
comparison libtomcrypt/notes/tech0005.txt @ 389:5ff8218bcee9
propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 2af95f00ebd5bb7a28b3817db1218442c935388e)
to branch 'au.asn.ucc.matt.dropbear' (head ecd779509ef23a8cdf64888904fc9b31d78aa933)
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Thu, 11 Jan 2007 03:14:55 +0000 |
| parents | 0cbe8f6dbf9e |
| children | f849a5ca2efc |
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| 388:fb54020f78e1 | 389:5ff8218bcee9 |
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| 1 Tech Note 0005 | |
| 2 Minimizing Code Space | |
| 3 Tom St Denis | |
| 4 | |
| 5 Introduction | |
| 6 ------------ | |
| 7 | |
| 8 Tweaking... | |
| 9 | |
| 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. | |
| 11 | |
| 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 | |
| 13 roughly 40KB of code (49KB on the ARMv4) (both excluding the math library). | |
| 14 | |
| 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 \ | |
| 16 -DLTC_HMAC -DYARROW -DMRSA -DMPI -DTFM_DESC -DARGTYPE=3 -Os -DLTC_SMALL_CODE -fomit-frame-pointer" make IGNORE_SPEED=1 | |
| 17 | |
| 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... | |
| 19 | |
| 20 Neato eh? |