I needed a lightweight way to SSH into my remote home server from my recently new (very, but very old, haha) Chromebook without burning through the battery. Spawning Crostini just to keep a terminal open runs a full Debian VM in the background, which drains the battery fast. Termius on Android is lighter, but the native ChromeOS Secure Shell app is just the most (I think) power-efficient option. The problem started when I tried importing my existing SSH key pair into the native app’s Identity dropdown and got slapped with a vague “invalid format” error every time I tried to connect.

What caused the error?

The ChromeOS Secure Shell app runs inside an isolated browser runtime (Native Client/WebAssembly), which makes its file parser far more strict than standard OpenSSH on Linux. It turns out two separate issues can trigger this exact error when importing a key.

How to fix it

First, the ChromeOS parser requires a strict trailing newline character (\n) at the very end of the private key file. If your key ends immediately after —–END OPENSSH PRIVATE KEY—– without a final blank line, the parser fails to detect the end tag. Just add an extra line at the end of the key-files, that’s all!