Unable to identify encrypted private keys in PEM/PKCS8 format

[lethalbit]

I was playing around and noticed that binwalk will outright ignore PEM private keys if they are encrypted or in PKCS8.

Binwalk Version: 3.1.0 (and as of a417b4d)

PEM Format

$ ssh-keygen -b 2048 -t rsa -m PEM -f /tmp/nya.pem
Generating public/private rsa key pair.
Enter passphrase for "/tmp/nya.pem" (empty for no passphrase): nyanyanya
Enter same passphrase again: nyanyanya
Your identification has been saved in /tmp/nya.pem
Your public key has been saved in /tmp/nya.pem.pub
<SNIP>
$ binwalk /tmp/nya.pem
Analyzed 1 file for 85 file signatures (187 magic patterns) in 6.0 milliseconds

PKCS#8

$ ssh-keygen -b 2048 -t rsa -m pkcs8 -f /tmp/nya.pkcs8
Generating public/private rsa key pair.
Enter passphrase for "/tmp/nya.pkcs8" (empty for no passphrase): nyanyanya
Enter same passphrase again: nyanyanya
Your identification has been saved in /tmp/nya.pkcs8
Your public key has been saved in /tmp/nya.pkcs8.pub
<SNIP>
$ binwalk /tmp/nya.pem
Analyzed 1 file for 85 file signatures (187 magic patterns) in 6.0 milliseconds

Normal

$ ssh-keygen -b 2048 -t rsa -f /tmp/nya.priv
Generating public/private rsa key pair.
Enter passphrase for "/tmp/nya.priv" (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /tmp/nya.priv
Your public key has been saved in /tmp/nya.priv.pub
<SNIP>
binwalk /tmp/nya.priv                    

                                                                    /tmp/nya.priv
----------------------------------------------------------------------------------------------------------------------------------------------------
DECIMAL                            HEXADECIMAL                        DESCRIPTION
----------------------------------------------------------------------------------------------------------------------------------------------------
0                                  0x0                                PEM private key
----------------------------------------------------------------------------------------------------------------------------------------------------

Analyzed 1 file for 85 file signatures (187 magic patterns) in 5.0 milliseconds