update ssh2john to support all algs from openssh

It's not about John itself but one of the companion tool provided with it: ssh2john.

https://github.com/openwall/john/blob/bleeding-jumbo/run/ssh2john.py

ssh2john supports a very limited set of algorithms

https://github.com/openwall/john/blob/173b5629e8dd6873819a94e2d3b3509ceffdfa38/run/ssh2john.py#L41-L45

Whereas most of the algs supported by openssh are not supported by ssh2john.

The following script can be used to generate a key for each alg and try to ssh2john it for each. You'll see a lot are not supported even if they are supported by John.

algs=("3des-cbc" "aes128-cbc" "aes128-ctr" "aes128-gcm@openssh.com" "aes192-cbc" "aes192-ctr" "aes256-cbc" "aes256-ctr" "aes256-gcm@openssh.com" "chacha20-poly1305@openssh.com")
for alg in "${algs[@]}"
do
    ssh-keygen -o -N test12345 -t ed25519 -Z $alg -f test_$alg 1>/dev/null
    ssh2john test_$alg > hash_$alg.txt
done

For example, EC with AES 128 looks supported but John but not by ssh2john

https://github.com/openwall/john/blob/173b5629e8dd6873819a94e2d3b3509ceffdfa38/src/ssh_fmt_plug.c#L375-L384

➜ ssh-keygen -o -N test12345 -t ecdsa -Z aes128-cbc -f test_ec+128
Generating public/private ecdsa key pair.
Your identification has been saved in test_ec+128
Your public key has been saved in test_ec+128.pub
The key fingerprint is:
SHA256:XIRSO83q23eYVERJDn7lBJ74bRm4tVWVw8LJcKL53lA noraj@norarch
The key's randomart image is:
+---[ECDSA 256]---+
|       ....o=+*oB|
|      . .=o.oX+O.|
|       .oo+ oE*o+|
|       . +. .o+.=|
|        S  o o.oo|
|       .  . +  . |
|        .  o +   |
|         o  + .  |
|        . .. .   |
+----[SHA256]-----+

➜ ssh2john test_ec+128
Traceback (most recent call last):
  File "/usr/bin/ssh2john", line 225, in <module>
    read_private_key(filename)
  File "/usr/bin/ssh2john", line 157, in read_private_key
    raise Exception('Unknown encryption type')
Exception: Unknown encryption type

ssh2hon from John the Ripper 1.9.0-jumbo-1+bleeding-173b5629e8 2024-01-18 00:08:42 +0100 MPI + OMP [linux-gnu 64-bit x86_64 AVX AC]

Start with run/ssh2john.py, especially the encryption-type handling around the referenced lines, then compare it with the supported algorithms in src/ssh_fmt_plug.c. Run the provided ssh-keygen and ssh2john loop for each OpenSSH algorithm to reproduce unsupported cases. Done means the companion tool processes the relevant OpenSSH algorithms that John supports without the reported unknown-encryption error.