OpenSSH private key format errors with LibreSSL 2.7

[Bernard Spil]

On 2018-04-07 11:24, Bernard Spil wrote:
> On 2018-04-07 9:04, Joel Sing wrote:
>> On Friday 06 April 2018 21:31:01 Bernard Spil wrote:
>>> Hi,
>>> 
>>> When using OpenSSH with LibreSSL 2.7.x it cannot read existing RSA 
>>> and
>>> ECDSA private keys.
>>> 
>>>      Error loading key "./id_rsa": invalid format
>>> 
>>> Rebuilding OpenSSH with LibreSSL 2.6.x fixes the issue. I had fixed 
>>> this
>>> issue early on with LibreSSL 2.7 by converting the key to "new file
>>> format" (to verify the ecdsa key wasn't corrupted I loaded it in
>>> 
>>> Fail:
>>> -----BEGIN EC PRIVATE KEY-----
>>> Proc-Type: 4,ENCRYPTED
>>> DEK-Info: AES-128-CBC,<snip>
>>> 
>>> -----BEGIN RSA PRIVATE KEY-----
>>> Proc-Type: 4,ENCRYPTED
>>> DEK-Info: AES-128-CBC,<snip>
>>> 
>>> Success (both keys after converting):
>>> -----BEGIN OPENSSH PRIVATE KEY-----
>>> 
>>> I've been digging through ssh-keygen to find a way to convert them 
>>> but
>>> have yet to find the right knobs. -e only exports public keys.
>>> 
>>> Currently running `make test` on OpenSSH 7.7 with LibreSSL 2.7.2.
>>> 
>>> Any hints?
>> 
>> What does the following say, when compiled with 2.7.2:
>> 
>> $ openssl version
>> $ openssl rsa -in ~/.ssh/id_rsa -noout ; echo $?
>> $ ssh -V
> 
> Meanwhile I've figured out that I can prevent issues if I convert the
> private key file to new format with
>    ssh-keygen -po -f keyfile
> I had saved my old key as id_rsa-oldformat
> 
> $ openssl version
> LibreSSL 2.7.2
> $ openssl rsa -in ~/.ssh/id_rsa-oldformat -noout
> Enter pass phrase for /home/bernard/.ssh/id_rsa-oldformat:
> $ echo $?
> 0
> $ ssh -V
> OpenSSH_7.2p2, LibreSSL 2.7.1
> $ /usr/local/bin/ssh -V
> OpenSSH_7.6p1, LibreSSL 2.7.1
> 
> I see that I need to recompile ssh with 2.7.2, the libraries they use
> are 2.7.2 not 2.7.1.
> 
> Cheers, Bernard.

To rule out issues with OpenSSH in base or ports on FreeBSD, I've now 
built a vanilla OpenSSH 7.7p1 linked against LibreSSL. No change.

$ ./configure --prefix=$HOME/openssh
$ make
$ make instal
$ cd ~/openssh/bin
$ ./ssh -V
OpenSSH_7.7p1, LibreSSL 2.7.2
$ ldd ./ssh
./ssh:
         libcrypto.so.43 => /lib/libcrypto.so.43 (0x8008c3000)
         libutil.so.9 => /lib/libutil.so.9 (0x800cab000)
         libz.so.6 => /lib/libz.so.6 (0x800ebf000)
         libcrypt.so.5 => /lib/libcrypt.so.5 (0x8010d8000)
         libc.so.7 => /lib/libc.so.7 (0x8012f7000)
$ ./ssh-add ~/.ssh/id_rsa-oldformat
Error loading key "/home/bernard/.ssh/id_rsa-oldformat": invalid format

Cheers, Bernard.