simplified minimal solution

.gitignore

@@ -1,2 +0,0 @@
-pwdb.json
-__pycache__

README.md

@@ -3,17 +3,6 @@
 ## Setup
 - Login with your username found on your name badge and set the initial password for your account:  https://git.aspp.school/user/login
 - You'll have to type that password many many times this week: choose wisely!
-- We will use the [exercise](exercise.md) in the repo for the rest of the lecture
-- find a partner to do pair-programming for this lecture by finding someone with the same tarot card as you
-- before starting, make yourself acquainted with the meanining and the power of the tarot cards: carefully read [this booklet](https://aspp.school/wiki/_media/tarot-runic.pdf)
-
-## A cautionary quote
-
-> My first instinct is to sell all my computers, fake my own death, move to another planet, and reinvent computing from scratch, rather than try to understand Git.
-> 
->    I rarely actually do that, mind you. But the urge is there.
-
-— Lars Wirzenius (Linux kernel developer)
 
 ## Warm-Up
 - how to start a repo from scratch?
@@ -30,11 +19,7 @@
 - how to *move* the whole working directory to a specific point in history?
     - `git checkout <commit>` ➔ `DETACHED HEAD` problem, __changes__ __files__
     - interaction with branches: `git branch <branch_name>` + `git switch <branch_name>` 
-- how to copy a file from a different branch:
-    - `git checkout <branch> <file>` ➔ the file is staged automatically
-    - `git restore --source=<branch> <file` ➔ the file is not staged
 - `git gui`: building commits along the way interactively (for the *mess around* type of workflows)
-- check out these [sketches](git-commands-visualizations.pdf) for a graphical visualization of git commands!
 
 ## The Open Source model
 - remotes: `git pull <from_where> <what>`, `git push <where> <what>`, `git fetch <from_where> <what>`, `git merge <another_branch>`

auth.py

@@ -1,88 +0,0 @@
-import getpass
-import json
-import pathlib
-import random
-import string
-import sys
-
-# name of the file where we store the pw database
-PWDB_FLNAME = pathlib.Path('pwdb.json')
-
-# list of valid characters for salt (only ASCII letters + digits + punctuation)
-CHARS = string.ascii_letters + string.digits + string.punctuation
-
-# length of salt
-SALT_LENGTH = 5
-
-def get_credentials():
-    # get input from terminal
-    username = input('Enter your username: ')
-    # get password using the appropriate module, so that typed characters are not
-    # echoed to the terminal
-    password = getpass.getpass('Enter your password: ')
-    return (username, password)
-
-def authenticate(username, pass_text, pwdb):
-    # get the salt from the database
-    salt = pwdb[username][1]
-    # calculate hash and compare with stored hash
-    return pwhash(pass_text, salt) == pwdb[username][0]
-
-def add_user(username, pwdb):
-    # do not try to add a username twice
-    if username in pwdb:
-        raise Exception(f'Username already exists [{username}]!')
-    else:
-        password = getpass.getpass(f'Enter password for {username}: ')
-        salt = get_salt()
-        pwdb[username] = (pwhash(password,salt), salt)
-    return pwdb
-
-def read_pwdb(pwdb_path):
-    if not pwdb_path.exists():
-        pwdb = {}
-    else:
-        with open(pwdb_path, 'rt') as pwdb_file:
-            pwdb = json.load(pwdb_file)
-    return pwdb
-
-def write_pwdb(pwdb, pwdb_path):
-    with open(pwdb_path, 'wt') as pwdb_file:
-        json.dump(pwdb, pwdb_file)
-
-def pwhash(pass_text, salt):
-    # simple additive hash -> very insecure!
-    hash_ = 0
-    full_pass_text = pass_text + salt
-    for idx, char in enumerate(full_pass_text):
-        # use idx as a multiplier, so that shuffling the characters returns a
-        # different hash
-        hash_ += (idx+1)*ord(char)
-    return hash_
-
-def get_salt():
-    salt_chars = random.choices(CHARS, k=SALT_LENGTH)
-    return ''.join(salt_chars)
-
-def main(pwdb_path):
-    # load the password database from file
-    pwdb = read_pwdb(pwdb_path)
-
-    # if we are passed an argument, we want to add a new user
-    if len(sys.argv) > 1:
-        pwdb = add_user(sys.argv[1], pwdb)
-        write_pwdb(pwdb, pwdb_path)
-        return
-
-    # ask for credentials
-    username, password = get_credentials()
-    if username not in pwdb or not authenticate(username, password, pwdb):
-        print('Wrong username or password!')
-    else:
-        print('Successfully authenticated!')
-
-    return
-
-if __name__ == '__main__':
-    main(PWDB_FLNAME)
-

cheatsheet.md

@@ -1,176 +0,0 @@
-# Git cheatsheet
-
-## Creating a repository
-```bash
-git init
-```
-Creates new git repository in current directory.
-
-```bash
-git clone <url> (<path>)
-```
-Clones the repository at the specified url. If no path is specified, the repository will
-be cloned into a directory with the same name as the remote repository.
-
-
-## Branches
-```bash
-git branch
-```
-Lists all branches in the repository.
-
-```bash
-git branch <branch-name>
-```
-Creates a new branch with the given name.
-
-```bash
-git switch <branch-name>
-```
-Switches to the specified branch.
-
-```bash
-git merge <branch-name>
-```
-Merges the specified branch into the current branch.
-
-
-## Making changes
-```bash
-git status
-```
-Shows the status of the repository. This includes the current branch and files that have been modified.
-
-```bash
-git diff (--staged)
-```
-Shows the changes that have been made to the files in the repository. Use `--staged` to see changes that have been added to the staging area.
-
-```bash
-git add <file>
-```
-Adds the specified file to the staging area.
-
-```bash
-git add .
-```
-Adds all files in the current directory to the staging area.
-
-```bash
-git reset (<file>)
-```
-Removes the specified file from the staging area. If no file is specified, all files are removed.
-
-```bash
-git commit (-m "<message>")
-```
-Commits all changes in the staging area to the current branch. If the `-m` flag is omitted, a text editor will open to write a commit message.
-
-```bash
-git commit --amend
-```
-Adds the staged changes to the last commit. This can be used for fixing typos in the commit message.
-
-
-## Undoing changes
-```bash
-git restore <file>
-```
-Restores the specified file to the state of the last commit. This undoes uncommitted changes.
-
-```bash
-git revert <commit>
-```
-Creates a new commit that undoes the changes of the specified commit. Use `git log` to find the hash of the commit.
-
-```bash
-git reset --hard <commit>
-```
-Resets the current branch to the specified commit. DANGER: This will remove all changes after the specified commit. Prefer `git revert`.
-
-
-## Looking at the history
-```bash
-git log (--oneline)
-```
-Shows all past commits on the current branch. Use `--oneline` to show a more compact view.
-
-```bash
-git show <commit>
-```
-Shows the changes of the specified commit. Use `git log` to find the has of the commit.
-
-
-## Remote repositories
-```bash
-git remote add <remote> <url>
-```
-Adds a new remote repository with the specified name (e.g. `origin` or `upstream`) and url. Origin is automatically created when cloning a repository.
-
-```bash
-git push <remote> <branch>
-```
-Pushes the specified branch to the remote repository.
-
-```bash
-git fetch <remote>
-```
-Fetches changes from the remote repository.
-
-```bash
-git pull <remote> <branch>
-```
-Fetches changes from the remote repository and merges them into the current branch.
-
-
-## Typical workflow
-```bash
-# 1. Fork the repository on GitHub / git.aspp.school
-
-# 2. Clone the repository
-git clone <fork-url>
-git remote add upstream <upstream-url>
-
-# 3. Create a new branch
-git branch <topic-branch>
-git switch <topic-branch>
-
-# 4. Make changes to the code
-
-# 5. Add and commit changes
-git add .
-git commit -m "<message>"
-
-# 6. Push changes to your fork
-git push origin <topic-branch>
-
-# 7. Create a pull request on GitHub / git.aspp.school
-
-# 8. Wait for the pull request to be reviewed and merged
-
-# 9. Pull changes from the remote repository
-git switch main
-git pull upstream main
-
-# 10. Delete the topic branch
-git branch -d <topic-branch>
-```
-
-Whenever the remote repository is updated (i.e. when a pull request is merged), you need to pull the changes into your local repository.
-```bash
-git switch main
-git pull upstream main
-
-# If you have an active topic branch, you need to rebase it on top of the updated main branch
-git switch <topic-branch>
-git rebase main
-```
-
-
-## Getting help
-```bash
-git help <command>
-```
-Shows the manual page for the specified command (`add`, `commit`, `push`, etc.).
-
-Official Git documentation: https://git-scm.com/docs

minimal_auth.py

@@ -0,0 +1,42 @@
+import json
+import sys
+
+def get_credentials():
+    username = input('Enter your username: ')
+    password = input('Enter your password: ')
+    return (username, password)
+
+def authenticate(username, password, pwdb):
+    return password == pwdb[username]
+
+def add_user(username, pwdb):
+    pwdb[username] = input(f'Enter password for {username}: ')
+    return pwdb
+
+def read_pwdb(pwdb_path):
+    try:
+        pwdb_file = open(pwdb_path, 'rt')
+        pwdb = json.load(pwdb_file)
+    except Exception:
+        pwdb = {}
+    return pwdb
+
+def write_pwdb(pwdb, pwdb_path):
+    pwdb_file = open(pwdb_path, 'wt')
+    json.dump(pwdb, pwdb_file)
+
+pwdb_path = 'pwdb.json'
+pwdb = read_pwdb(pwdb_path)
+
+if len(sys.argv) > 1:
+    pwdb = add_user(sys.argv[1], pwdb)
+    write_pwdb(pwdb, pwdb_path)
+else:
+    username, password = get_credentials()
+    if username not in pwdb:
+        print('Wrong username!')
+    else:
+        if authenticate(username, password, pwdb):
+            print('Successfully authenticated!')
+        else:
+            print('Wrong password!')