Mercurial > dropbear
annotate SMALL @ 1672:3a97f14c0235
Add Chacha20-Poly1305, AES128-GCM and AES256-GCM support (#93)
* Add Chacha20-Poly1305 authenticated encryption
* Add general AEAD approach.
* Add [email protected] algo using LibTomCrypt chacha and
poly1305 routines.
Chacha20-Poly1305 is generally faster than AES256 on CPU w/o dedicated
AES instructions, having the same key size.
Compiling in will add ~5,5kB to binary size on x86-64.
function old new delta
chacha_crypt - 1397 +1397
_poly1305_block - 608 +608
poly1305_done - 595 +595
dropbear_chachapoly_crypt - 457 +457
.rodata 26976 27392 +416
poly1305_process - 290 +290
poly1305_init - 221 +221
chacha_setup - 218 +218
encrypt_packet 1068 1270 +202
dropbear_chachapoly_getlength - 147 +147
decrypt_packet 756 897 +141
chacha_ivctr64 - 137 +137
read_packet 543 637 +94
dropbear_chachapoly_start - 94 +94
read_kex_algos 792 880 +88
chacha_keystream - 69 +69
dropbear_mode_chachapoly - 48 +48
sshciphers 280 320 +40
dropbear_mode_none 24 48 +24
dropbear_mode_ctr 24 48 +24
dropbear_mode_cbc 24 48 +24
dropbear_chachapoly_mac - 24 +24
dropbear_chachapoly - 24 +24
gen_new_keys 848 854 +6
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(add/remove: 14/0 grow/shrink: 10/0 up/down: 5388/0) Total: 5388 bytes
* Add AES128-GCM and AES256-GCM authenticated encryption
* Add general AES-GCM mode.
* Add [email protected] and [email protected] algo using
LibTomCrypt gcm routines.
AES-GCM is combination of AES CTR mode and GHASH, slower than AES-CTR on
CPU w/o dedicated AES/GHASH instructions therefore disabled by default.
Compiling in will add ~6kB to binary size on x86-64.
function old new delta
gcm_process - 1060 +1060
.rodata 26976 27808 +832
gcm_gf_mult - 820 +820
gcm_add_aad - 660 +660
gcm_shift_table - 512 +512
gcm_done - 471 +471
gcm_add_iv - 384 +384
gcm_init - 347 +347
dropbear_gcm_crypt - 309 +309
encrypt_packet 1068 1270 +202
decrypt_packet 756 897 +141
gcm_reset - 118 +118
read_packet 543 637 +94
read_kex_algos 792 880 +88
sshciphers 280 360 +80
gcm_mult_h - 80 +80
dropbear_gcm_start - 62 +62
dropbear_mode_gcm - 48 +48
dropbear_mode_none 24 48 +24
dropbear_mode_ctr 24 48 +24
dropbear_mode_cbc 24 48 +24
dropbear_ghash - 24 +24
dropbear_gcm_getlength - 24 +24
gen_new_keys 848 854 +6
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(add/remove: 14/0 grow/shrink: 10/0 up/down: 6434/0) Total: 6434 bytes
| author | Vladislav Grishenko <themiron@users.noreply.github.com> |
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| date | Mon, 25 May 2020 20:50:25 +0500 |
| parents | b9d3f725e00b |
| children | 13cb8cc1b0e4 |
| rev | line source |
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1 Tips for a small system: |
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2 |
| 161 | 3 If you only want server functionality (for example), compile with |
| 4 make PROGRAMS=dropbear | |
| 5 rather than just | |
| 6 make dropbear | |
| 7 so that client functionality in shared portions of Dropbear won't be included. | |
| 8 The same applies if you are compiling just a client. | |
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9 |
| 161 | 10 --- |
| 11 | |
| 12 The following are set in options.h: | |
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13 |
| 161 | 14 - You can safely disable blowfish and twofish ciphers, and MD5 hmac, without |
| 15 affecting interoperability | |
| 16 | |
| 17 - If you're compiling statically, you can turn off host lookups | |
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18 |
| 161 | 19 - You can disable either password or public-key authentication, though note |
| 20 that the IETF draft states that pubkey authentication is required. | |
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21 |
| 161 | 22 - Similarly with DSS and RSA, you can disable one of these if you know that |
| 23 all clients will be able to support a particular one. The IETF draft | |
| 24 states that DSS is required, however you may prefer to use RSA. | |
| 25 DON'T disable either of these on systems where you aren't 100% sure about | |
| 26 who will be connecting and what clients they will be using. | |
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27 |
| 161 | 28 - Disabling the MOTD code and SFTP-SERVER may save a small amount of codesize |
| 29 | |
| 30 - You can disable x11, tcp and agent forwarding as desired. None of these are | |
| 31 essential, although agent-forwarding is often useful even on firewall boxes. | |
| 32 | |
| 33 --- | |
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34 |
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35 If you are compiling statically, you may want to disable zlib, as it will use |
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36 a few tens of kB of binary-size (./configure --disable-zlib). |
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37 |
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38 You can create a combined binary, see the file MULTI, which will put all |
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39 the functions into one binary, avoiding repeated code. |
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40 |
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41 If you're compiling with gcc, you might want to look at gcc's options for |
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42 stripping unused code. The relevant vars to set before configure are: |
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43 |
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44 LDFLAGS=-Wl,--gc-sections |
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45 CFLAGS="-ffunction-sections -fdata-sections" |
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46 |
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47 You can also experiment with optimisation flags such as -Os, note that in some |
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48 cases these flags actually seem to increase size, so experiment before |
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49 deciding. |
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50 |
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51 Of course using small C libraries such as uClibc and dietlibc can also help. |
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52 |
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53 If you have any queries, mail me and I'll see if I can help. |