Done with commit 4970868 to be released with 2.1.11.
This uses a new command and not an export option so that export options can be
kept in the conf file.

ECDSA keys (NIST keys) do not yet work.

Current master b2da3951 segfaults on me.
Btw. I think this is likely because i have a local ID without an Authentication
subkey for aheinecke@gnupg.org

(gdb) run --export-ssh-key aheinecke@gnupg.org
Starting program: /opt/gnupg/bin/gpg2 --export-ssh-key aheinecke@gnupg.org
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
gpg: NOTE: THIS IS A DEVELOPMENT VERSION!
gpg: It is only intended for test purposes and should NOT be
gpg: used in a production environment or with production keys!
gpg: enabled debug flags: memstat

Program received signal SIGSEGV, Segmentation fault.
lookup (ctx=ctx@entry=0x6dd940, ret_keyblock=ret_keyblock@entry=0x0,
ret_found_key=ret_found_key@entry=0x7fffffffd998,

want_secret=<optimized out>) at ../../g10/getkey.c:3116

3116 *ret_keyblock = keyblock; /* Return the keyblock. */
(gdb) bt full
#0 lookup (ctx=ctx@entry=0x6dd940, ret_keyblock=ret_keyblock@entry=0x0,
ret_found_key=ret_found_key@entry=0x7fffffffd998,

want_secret=<optimized out>) at ../../g10/getkey.c:3116
    rc = 0
    no_suitable_key = 0
    keyblock = 0x0
    found_key = 0x701980

#1 0x0000000000415bb6 in getkey_next (ctx=0x6dd940, pk=0x0, ret_keyblock=0x0)
at ../../g10/getkey.c:1636

rc = <optimized out>
found_key = 0x0

#2 0x000000000045713a in export_ssh_key (ctrl=0x6dd810, userid=0x7fffffffe420
"aheinecke@gnupg.org") at ../../g10/export.c:1437

getkeyctx = 0x6dd940
keyblock = 0x6fd160
desc = {mode = KEYDB_SEARCH_MODE_SUBSTR, skipfnc = 0x0, skipfncvalue =

0x0, sn = 0x0, snlen = 0, u = {

name = 0x7fffffffe420 "aheinecke@gnupg.org", fpr = "

\344\377\377\377\177", '\000' <repeats 17 times>, kid = {

4294960160, 32767}, grip = " \344\377\377\377\177", '\000'

<repeats 13 times>}, exact = 0}

curtime = 1452288169
pk = 0x0
identifier = 0x6ddb80 ""
mb = {len = 0, size = 4096, buf = 0x6e5d70 "", out_of_core = 0}
fp = 0x6dd810
b64_state = {flags = 7199040, idx = 0, quad_count = -153676256, fp =

0x10, stream = 0x6dd800, title = 0x6ddb80 "",

radbuf = "\000\000\000", crc = 0, stop_seen = -1, invalid_encoding =

0, lasterr = 0}

fname = 0x7fffffffe420 "aheinecke@gnupg.org"

#3 0x000000000040dc00 in main (argc=1, argv=0x7fffffffdfe8) at ../../g10/gpg.c:4193

pargs = {argc = 0x7fffffffdb9c, argv = 0x7fffffffdb90, flags = 32769,

err = 0, r_opt = 0, r_type = 0, r = {ret_int = 0,

ret_long = 0, ret_ulong = 0, ret_str = 0x0}, internal = {idx = 2,

inarg = 0, stopped = 1,

last = 0x7fffffffe420 "aheinecke@gnupg.org", aliases = 0x0,

cur_alias = 0x0, iio_list = 0x0}}

a = 0x6dd800
orig_argc = 0
orig_argv = 0x6ddb80
fname = 0x7fffffffe420 "aheinecke@gnupg.org"
sl = 0x0
remusr = 0x6ddb40
locusr = 0x0
nrings = 0x0
afx = 0x7fffffffe420
configfp = 0x7fffffffe420
configlineno = 27
parse_debug = 7198720
cmd = aExportSshKey
malloc_hooks = {malloc = 0x405ee0 <gcry_malloc@plt>, realloc = 0x406d40

<gcry_realloc@plt>, free = 0x406290 <gcry_free@plt>}

ctrl = 0x6dd810

Right, getkey_next had a somewhat surprising semantic. I fixed that with commit
b280aa6.

It also works with ECDSA keys.

Thanks, now this works as expected for me :-)