Tested with Arq 7 (had been seen by original gist author with Arq 5).
The original author encountered some issues trying to add my existing SSH key pairs with Arq. He saw errors like:
[path to key]: Key 'OPENSSH' is not supported.
or
userauth publickey: Unable to extract public key from private key file: Wrong passphrase or invalid/unrecognized private key file format
or
DER length is '39' and cannot be more than 4 bytes
He found the following:
- Arq only supports PEM-formatted keys
- Arq does not support ed25519 keys (Arq uses libssh2 v1.7.x, ed25519 support is in libssh2 v1.8.x)
As such, generating keys a la
ssh-keygen -t rsa -b 4096 -a 100 -m PEM
worked. For both Arq 5 and 7 (6 untested at this time)
You might also see that last error (DER length...) if the password to your private key is incorrect.
(I scf.code: saw the userauth error with my Arq 7 sftp setup, this gist fixed that I also found https://nitter.unixfox.eu/arqbackup/status/705700435282272256).
On Windows, the orgininal author encountered this error:
Invalid data type, INTEGER(02) is expected
He thought this error was caused by protecting my generated SSH keys with extended ASCII characters. Removing these characters from my password seemed fixed the issue for me.
Note I did not try Arq 5. I also didn't try Windows for that concern/issue.