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

.TH dropbearkey 1
.SH NAME
dropbearkey \- create private keys for the use with dropbear(8) or dbclient(1)
.SH SYNOPSIS
.B dropbearkey
\-t
.I type
\-f
.I file
[\-s
.IR bits ]
[\-y]
.SH DESCRIPTION
.B dropbearkey
generates a
\fIRSA\fR, \fIDSS\fR, \fIECDSA\fR, or \fIEd25519\fR
format SSH private key, and saves it to a file for the use with the
Dropbear client or server.
Note that 
some SSH implementations
use the term "DSA" rather than "DSS", they mean the same thing.
.SH OPTIONS
.TP
.B \-t \fItype
Type of key to generate.
Must be one of
.I rsa
.I ecdsa
.I ed25519
or
.IR dss .
.TP
.B \-f \fIfile
Write the secret key to the file
\fIfile\fR. For client authentication ~/.ssh/id_dropbear is loaded by default
.TP
.B \-s \fIbits
Set the key size to
.I bits
bits, should be multiple of 8 (optional). 
.TP
.B \-y
Just print the publickey and fingerprint for the private key in \fIfile\fR.
.SH NOTES
The program dropbearconvert(1) can be used to convert between Dropbear and OpenSSH key formats.
.P
Dropbear does not support encrypted keys. 
.SH EXAMPLE
generate a host-key:
 # dropbearkey -t rsa -f /etc/dropbear/dropbear_rsa_host_key

extract a public key suitable for authorized_keys from private key:
 # dropbearkey -y -f id_rsa | grep "^ssh-rsa " >> authorized_keys
.SH AUTHOR
Matt Johnston ([email protected]).
.br
Gerrit Pape ([email protected]) wrote this manual page.
.SH SEE ALSO
dropbear(8), dbclient(1), dropbearconvert(1)
.P
https://matt.ucc.asn.au/dropbear/dropbear.html