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 ------------------------------------------------------------------------------ (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 ------------------------------------------------------------------------------ (add/remove: 14/0 grow/shrink: 10/0 up/down: 6434/0) Total: 6434 bytes

Dropbear for Debian
-------------------

This package will attempt to listen on port 22. If the OpenSSH 
package ("ssh") is installed, the file /etc/default/dropbear 
will be set up so that the server does not start by default.

You can run Dropbear concurrently with OpenSSH 'sshd' by 
modifying /etc/default/dropbear so that "NO_START" is set to 
"0" and changing the port number that Dropbear runs on. Follow 
the instructions in the file.

This package suggests you install the "ssh" package. This package 
provides the "ssh" client program, as well as the "/usr/bin/scp" 
binary you will need to be able to retrieve files from a server 
running Dropbear via SCP.

Replacing OpenSSH "sshd" with Dropbear
--------------------------------------

You will still want to have the "ssh" package installed, as it 
provides the "ssh" and "scp" binaries. When you install this 
package, it checks for existing OpenSSH host keys and if found, 
converts them to the Dropbear format.

If this appears to have worked, you should be able to change over 
by following these steps:

1. Stop the OpenSSH server
   % /etc/init.d/ssh stop
2. Prevent the OpenSSH server from starting in the future
   % touch /etc/ssh/sshd_not_to_be_run
3. Modify the Dropbear defaults file, set NO_START to 0 and 
   ensure DROPBEAR_PORT is set to 22.
   % editor /etc/default/dropbear
4. Restart the Dropbear server.
   % /etc/init.d/dropbear restart

See the Dropbear homepage for more information:
  http://matt.ucc.asn.au/dropbear/dropbear.html