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

#!/bin/sh
### BEGIN INIT INFO
# Provides:          dropbear
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Dropbear SSH server
### END INIT INFO
#
# Do not configure this file. Edit /etc/default/dropbear instead!
#

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
DAEMON=/usr/sbin/dropbear
NAME=dropbear
DESC="Dropbear SSH server"

DROPBEAR_PORT=22
DROPBEAR_EXTRA_ARGS=
NO_START=0

set -e

cancel() { echo "$1" >&2; exit 0; };
test ! -r /etc/default/dropbear || . /etc/default/dropbear
test -x "$DAEMON" || cancel "$DAEMON does not exist or is not executable."
test ! -x /usr/sbin/update-service || ! update-service --check dropbear ||
  cancel 'The dropbear service is controlled through runit, use the sv(8) program'

test -z "$DROPBEAR_BANNER" || \
  DROPBEAR_EXTRA_ARGS="$DROPBEAR_EXTRA_ARGS -b $DROPBEAR_BANNER"
test -n "$DROPBEAR_RSAKEY" || \
  DROPBEAR_RSAKEY="/etc/dropbear/dropbear_rsa_host_key"
test -n "$DROPBEAR_DSSKEY" || \
  DROPBEAR_DSSKEY="/etc/dropbear/dropbear_dss_host_key"
test -n "$DROPBEAR_RECEIVE_WINDOW" || \
  DROPBEAR_RECEIVE_WINDOW="65536"

case "$1" in
  start)
	test "$NO_START" = "0" || cancel 'NO_START is not set to zero.'
	echo -n "Starting $DESC: "
	start-stop-daemon --start --quiet --pidfile /var/run/"$NAME".pid \
	  --exec "$DAEMON" -- -d "$DROPBEAR_DSSKEY" -r "$DROPBEAR_RSAKEY" \
	    -p "$DROPBEAR_PORT" -W "$DROPBEAR_RECEIVE_WINDOW" $DROPBEAR_EXTRA_ARGS
	echo "$NAME."
	;;
  stop)
	echo -n "Stopping $DESC: "
	start-stop-daemon --stop --quiet --oknodo --pidfile /var/run/"$NAME".pid
	echo "$NAME."
	;;
  restart|force-reload)
	test "$NO_START" = "0" || cancel 'NO_START is not set to zero.'
	echo -n "Restarting $DESC: "
	start-stop-daemon --stop --quiet --oknodo --pidfile /var/run/"$NAME".pid
	sleep 1
	start-stop-daemon --start --quiet --pidfile /var/run/"$NAME".pid \
	  --exec "$DAEMON" -- -d "$DROPBEAR_DSSKEY" -r "$DROPBEAR_RSAKEY" \
	    -p "$DROPBEAR_PORT" -W "$DROPBEAR_RECEIVE_WINDOW" $DROPBEAR_EXTRA_ARGS
	echo "$NAME."
	;;
  *)
	N=/etc/init.d/$NAME
	echo "Usage: $N {start|stop|restart|force-reload}" >&2
	exit 1
	;;
esac

exit 0