First version of passphrase generator

README.md

@@ -1,2 +1,43 @@
 # passphrase_generator
+
 Leverages Python's [secrets](https://docs.python.org/3/library/secrets.html) module to generate a secure passphrase from a wordlist
+
+## Installation
+
+Other than cloning this repo, no installation is required.
+
+All of `genpass.py` dependencies are Python 3.6 built-in libraries.
+
+## Usage
+
+### Wordlists
+
+By default, `genpass.py` uses the [`words.txt` file](https://github.com/dwyl/english-words/blob/master/words.txt) (from commit [11735d0](https://github.com/dwyl/english-words/commit/11735d0d68f051b817ad224e14d999acc94fcf00) of [dwyl's english-words repo](https://github.com/dwyl/english-words)) to generate a passphrase.
+
+`words.txt` contains words that may include numbers and/or symbols. If you don't want to use words with numbers/symbols in them to generate your password, you can instead use [`words_alpha.txt`](https://github.com/dwyl/english-words/blob/master/words_alpha.txt) by calling `genpass.py` with the `-w` option, like this:
+
+```bash
+./genpass.py -w ./wordlists/words_alpha.txt
+```
+
+If you need, you can update `words.txt` and/or `words_alpha.txt` with a later commit from dwyl's repo.
+
+Otherwise, if you so wish, you can create your own wordlist to generate passphrases from, and use them the same way you specify to use `words_alpha.txt` instead of `words.txt`.
+
+### Generating passphrases
+
+By default, `genpass.py` generates a single, 4-word-long passphrase without spaces.
+
+If you want to generate more than one passphrase at once, you can use the `-n` option to specify an integer value of the number of passphrases you want to generate.
+
+Similarly, if you want to generate a passphrase of custom length, simply use the `-l` option to specify an integer value of the number of words you want your passphrase to include.
+
+Finally, if you want your passphrase to include spaces (although I don't necessarily recommend this - a surprising number of systems don't support spaces in passwords), simply use `--spaces` when calling `genpass.py`.
+
+## Contributing
+
+Pull requests are welcome for this project. Please include as much detail as possible about the changes, including:
+
+* What they are
+* Why you've made them or why you think they're needed
+

genpass.py

@@ -0,0 +1,88 @@
+#!/usr/bin/env python
+
+import argparse
+import os
+import secrets
+
+def parse_args():
+    parser = argparse.ArgumentParser("Secure passphrase generator")
+    parser.add_argument(
+        "-w",
+        "--wordlist",
+        type=str,
+        dest="wordlist_path",
+        default="./wordlists/words.txt",
+        help="Specify a path to a wordlist"
+    )
+    parser.add_argument(
+        "-n",
+        "--num",
+        type=int,
+        dest="num_passwds",
+        default=1,
+        help="Specify the number of passphrases to generate"
+    )
+    parser.add_argument(
+        "-l",
+        "--length",
+        type=int,
+        dest="passwd_size",
+        default=4,
+        help="Specify the length (in words) of the generated passphrase(s)"
+    )
+    parser.add_argument(
+        "--spaces",
+        action="store_true",
+        dest="use_spaces",
+        default=False,
+        help="Use this to generate a passphrase with spaces between each word"
+    )
+
+    args = parser.parse_args()
+
+    # We only want to accept valid file paths
+    if not os.path.isfile(args.wordlist_path):
+        raise OSError("Specified path to wordlist is either invalid or does not exist. Exiting...")
+        exit(1)
+    else:
+        return args
+
+def gen_pass(length, use_spaces, wordlist):
+    """Generate a secure passphrase
+
+    Params:
+    - length (int)
+        The length of the password to generate (in number of words)
+    - use_spaces (bool)
+        Generate passphrase with or without spaces
+    - wordlist (list)
+        A list of individual words
+
+    Returns:
+    - string
+    """
+    phrase = ""
+    last_word = False
+    for i in range (0, length -1):
+        if i == length - 1:
+            last_word = True
+        index = secrets.randbelow(len(wordlist) - 1)
+        phrase += wordlist[index]
+        if not last_word and use_spaces:
+            phrase += " "
+
+    return phrase
+
+if __name__ == "__main__":
+
+    args = parse_args()
+
+    wordlist = []
+    with open(args.wordlist_path, "r") as wordlist_file:
+        wordlist_raw = wordlist_file.readlines()
+        for word in wordlist_raw:
+            wordlist.append(word.rstrip())
+
+    for i in range (0, args.num_passwds):
+        print(gen_pass(args.passwd_size, args.use_spaces, wordlist))
+