# GitHub

<div class="admonition note">
<p class="first admonition-title">
Note
</p>
<p class="last">
It is no longer necessary to configure <a href="#ssh">SSH</a> or create a <a href="#personal-access-token">personal access token</a> when using <a href="/code/">Visual Studio Code for CS50</a> at <a href="https://cs50.dev/">cs50.dev</a>. Both <code class="docutils literal notranslate"><span class="pre">check50</span></code> and <code class="docutils literal notranslate"><span class="pre">submit50</span></code> should "just work," so long as you have logged into <a href="https://submit.cs50.io/">submit.cs50.io</a> at least once.
</p>
</div>

Tools like [check50](https://cs50.readthedocs.io/projects/check50/en/latest/) and [submit50](/submit50/) rely on `git`, a popular tool for saving different versions of code, and [GitHub](https://github.com/), a popular website for saving those versions in the cloud. To push (i.e., save) your code to GitHub using `git`, it used to be possible to log into GitHub via a command line (as in a terminal window) using a GitHub username and password. As of [August 13, 2021](https://github.blog/2020-12-15-token-authentication-requirements-for-git-operations/), that's no longer possible, which means you can no longer use `check50` or `submit50` using your GitHub username and password either.

But you can still use `check50` and `submit50`! You just need to log in a bit differently, either using [SSH](#ssh) or a [personal access token](#personal-access-token). Odds are you'll find SSH more convenient for [Visual Studio Code](/code/) and [CS50 IDE](/ide/index), and personal access tokens more convenient for [CS50 Sandbox](/sandbox/) and [CS50 Lab](/lab/).

***

## SSH

1. Open a terminal window, if not open already, within [Visual Studio Code](/code/), [CS50 IDE](/ide/index), [CS50 Sandbox](/sandbox/), or [CS50 Lab](/lab/).
1. Execute `ssh-keygen`. When prompted to "save the key," just hit Enter, without typing anything.
1. You'll then be prompted for a "passphrase" (i.e., password). If you only use your GitHub account for CS50, no need to input a passphrase; just hit Enter. Otherwise, input a passphrase (that you won't forget!), then hit Enter, then input it again, then hit Enter again. For security's sake, you won't see what you type. You'll then see a "randomart image" that you can ignore.
1. Execute `cat ~/.ssh/id_rsa.pub`. You'll then see your "public key," multiple lines of seemingly random text. Highlight and copy all of those lines, starting with `ssh-rsa` to the end. **But don't highlight your terminal window's prompts (which contain `$`) before or after those lines.**
1. Visit [https://github.com/settings/keys](https://github.com/settings/keys), logging in with your GitHub username and password as usual. Don't use the passphrase you just created, if any.
1. Click **New SSH Key**.
1. Paste your public key into the text box under **Key**. Optionally input a title under **Title** (e.g., `CS50`).
1. Click **Add SSH Key**.
1. Execute `ssh -T git@ssh.github.com -p 443`.
1. Enter "yes" and press enter if you see the following prompt (the IP address might be different):
    ```
    The authenticity of host '[ssh.github.com]:443 ([140.82.113.35]:443)' can't be established.
    ED25519 key fingerprint is SHA256:7KMZvJiITZ+HbOyqjKJV2AeC5As3GSZES5abcd1NIe4.
    This key is not known by any other names
    Are you sure you want to continue connecting (yes/no/[fingerprint])?
    ```
1. If you input a "passphrase" (i.e., password) earlier, enter the passphrase and press Enter when you see the following prompt  `"Enter passphrase for key 'home/ubuntu/.ssh/id_rsa':"`
1. You should be greeted with `"Hi USERNAME! You've successfully authenticated, but GitHub does not provide shell access."`  If you don't see that, review the above steps to verify you didn't skip something.

You should now be able to use `check50` and `submit50` (and `git`) without GitHub username and password. But if you created a passphrase, you might still be prompted for that.

### If you created a passphrase but forgot it

1. Visit [https://github.com/settings/keys](https://github.com/settings/keys), click **Delete** next to your old SSH key, then click **I understand, please delete this SSH key**.
1. Follow all of the same [SSH](#ssh) steps, above, again. When prompted to "overwrite" (your old key), input `y`, then hit Enter.

***

## Personal Access Token

1. Visit [https://github.com/settings/security](https://github.com/settings/security), logging in with your GitHub username and password as usual, and [configure two-factor authentication](https://docs.github.com/en/github/authenticating-to-github/securing-your-account-with-two-factor-authentication-2fa/configuring-two-factor-authentication).
1. Visit [https://github.com/settings/tokens](https://github.com/settings/tokens).
1. Click **Generate new token**.
1. Input a note under **Note** (e.g., `CS50 IDE` if using CS50 IDE).
1. Select **No expiration** (or something shorter) via the drop-down menu under **Note**.
1. Check **repo** under **Select scopes**.
1. Click **Generate token**.
1. Highlight and copy the "personal access token" that appears. Odds are it will start with `ghp_`.
1. Paste that personal access token somewhere safe (e.g., in a password manager).

You should now be able to use `check50` and `submit50` (and `git`) without GitHub username and password. When prompted to log in, use your GitHub username and that personal access token instead of your password.

### If you created a personal access token but forgot it (or it expired)

1. Visit [https://github.com/settings/tokens](https://github.com/settings/tokens), click **Delete** next to your old personal access token, then click **I understand, delete this token**.
1. Follow all of the same [Personal Access Token](#personal-access-token) steps, above, again.