Windows Subsystem for Linux: never prompt ssh passphrase again

keychain.ps1

$credentials = Get-StoredCredential -Target sshpassphrase
$BSTR = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($credentials.Password)
$passphrase = [System.Runtime.InteropServices.Marshal]::PtrToStringAuto($BSTR)
C:\Windows\System32\wsl.exe -u [YOUR_WSL_USERNAME] -d [YOUR_DISTRIBUTION] /home/[YOUR_WSL_USERNAME]/wslu/keychain.sh $passphrase

keychain.sh

#!/bin/bash
SSH_ASKPASS_SCRIPT=/tmp/ssh-askpass-script
cat > ${SSH_ASKPASS_SCRIPT} <<EOL
#!/bin/bash
echo "$1"
EOL
chmod u+x ${SSH_ASKPASS_SCRIPT}
export DISPLAY="0"
export SSH_ASKPASS=${SSH_ASKPASS_SCRIPT}
/usr/bin/keychain --clear id_rsa
rm ${SSH_ASKPASS_SCRIPT}