I am having trouble signing commits. With the following git config:

```
user.name=Bob
user.email=[bob's email]
user.signingkey=ABCDEFGH
user.user=bob1
gpg.program=gpg2

```

I was told to include only the first eight characters of the secret key.

After staging, upon `git commit -S -m "commit message"`, I receive the following errors:

```
error: gpg failed to sign the data
fatal: failed to write commit object

```

It seems that most users who encounter this error are on Macs and have some extra setup to do. But I'm on Kali Linux.

Any advice?