Permission denied (publickey).

I am having difficulty in publishing my code to github via the command line and also while using GitHub Desktop for macOS.

$ git push -u origin master
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

It used to work on my Ubuntu 14.04 laptop years ago, but I haven’t checked it since I migrated to macOS.

Not sure what the problem is.

git config --list
credential.helper=osxkeychain
filter.lfs.smudge=git-lfs smudge -- %f
filter.lfs.process=git-lfs filter-process
filter.lfs.required=true
filter.lfs.clean=git-lfs clean -- %f
user.name=Anjanesh Lekshminarayanan
user.email=my-correct-email-id@provider.com
core.repositoryformatversion=0
core.filemode=true
core.bare=false
core.logallrefupdates=true
core.ignorecase=true
core.precomposeunicode=true
remote.origin.url=git@github.com:anjanesh/flask-test.git
remote.origin.fetch=+refs/heads/*:refs/remotes/origin/*