ConnectBot cannot import OpenSSH keys

January 8, 2020

The free open source SSH app ConnectBot allows connecting to SSH servers with port forwarding using public key authentication, including ED25519.

Sometimes it’s necessary to share SSH keypairs on multiple clients. Perhaps the server owner isn’t willing to bother with more than one SSH client key. ConnectBot has an open issue since it cannot import OpenSSH keys created on a PC.

Generally users should create unique SSH public/private keypairs for each device. Sharing keys between devices means if a device is compromised, deleting its key from ~/.ssh/authorized_keys on the SSH server disables all other devices sharing that key.

Workaround by creating an SSH keypair in ConnectBot. Copy the ConnectBot-created public/private keypair to the PC ~/.ssh directory.

The stem (filename without extension) of the public and private keys must match. The public key should have a .pub suffix, while the private key has no suffix.

Thereby the same SSH keypair is used on the phone with ConnectBot and the PC with OpenSSH client.