commit with gpg.format ssh results in "cryptographic error"

[razvan]

Describe the bug

git is configured to sign commits with ssh.

The key pair length is 4096.

Commit fails with the error message in subject without any additional information.

To Reproduce

Nothing out of the ordinary. Just try to commit a change.

The relevant parts in .gitconfig :

[user]
        signingkey = /home/razvan/.github/sign
[gpg]
        format = ssh
[commit]
        gpgsign = true
[tag]
        gpgsign = true

Expected behavior

I should be able to commit changes.

Context (please complete the following information):

• OS: Fedora Linux 43 (Workstation Edition)
• GitUI Version: both 0.27.0 (dnf package) as well as cargo build --release from main
• Rust version: 1.86.0

Additional context

Excerpt from gitui.log:

❯ rg ERROR ~/.cache/gitui/gitui.log 
1:12:29:57 [ERROR] theme error ["/home/razvan/.config/gitui/theme.ron"]: No such file or directory (os error 2)
50:12:30:07 [ERROR] commit error: sign error: Failed to spawn signing process: cryptographic error

I can also confirm that both git commit as well as lazygit work, so I don't believe it's a problem with my setup.