Mercurial > dropbear
view 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> |
---|---|
date | Mon, 25 May 2020 20:50:25 +0500 |
parents | b9d3f725e00b |
children | 13cb8cc1b0e4 |
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Tips for a small system: If you only want server functionality (for example), compile with make PROGRAMS=dropbear rather than just make dropbear so that client functionality in shared portions of Dropbear won't be included. The same applies if you are compiling just a client. --- The following are set in options.h: - You can safely disable blowfish and twofish ciphers, and MD5 hmac, without affecting interoperability - If you're compiling statically, you can turn off host lookups - You can disable either password or public-key authentication, though note that the IETF draft states that pubkey authentication is required. - Similarly with DSS and RSA, you can disable one of these if you know that all clients will be able to support a particular one. The IETF draft states that DSS is required, however you may prefer to use RSA. DON'T disable either of these on systems where you aren't 100% sure about who will be connecting and what clients they will be using. - Disabling the MOTD code and SFTP-SERVER may save a small amount of codesize - You can disable x11, tcp and agent forwarding as desired. None of these are essential, although agent-forwarding is often useful even on firewall boxes. --- If you are compiling statically, you may want to disable zlib, as it will use a few tens of kB of binary-size (./configure --disable-zlib). You can create a combined binary, see the file MULTI, which will put all the functions into one binary, avoiding repeated code. If you're compiling with gcc, you might want to look at gcc's options for stripping unused code. The relevant vars to set before configure are: LDFLAGS=-Wl,--gc-sections CFLAGS="-ffunction-sections -fdata-sections" You can also experiment with optimisation flags such as -Os, note that in some cases these flags actually seem to increase size, so experiment before deciding. Of course using small C libraries such as uClibc and dietlibc can also help. If you have any queries, mail me and I'll see if I can help.