I had a similar issue but I was at work and don't have the ability to change file permissions on my work computer. What you need to do is install [WSL][1] then copy the your key to the hidden ssh directory in WSL:

cp <path to your key> ~/.ssh/<name of your key>

Now you should be able to modify the permissions normally.

sudo chmod 600 ~/.ssh/<your key's name>

Then ssh using WSL:

ssh -i ~/.ssh/<name of your key> <username>@<ip address> [1]: https://docs.microsoft.com/en-us/windows/wsl/install-win10

I had a similar issue but I was at work and don't have the ability to change file permissions on my work computer. What you need to do is install WSL then copy the your key to the hidden ssh directory in WSL:

cp <path to your key> ~/.ssh/<name of your key>

Now you should be able to modify the permissions normally.

sudo chmod 600 ~/.ssh/<your key's name>

Then ssh using WSL:

ssh -i ~/.ssh/<name of your key> <username>@<ip address>