ENH: add function that generates passwords

Summary

Function that can create passwords for administrative uses.

Test Environment

Manual testing

Check List for the Author

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• All automated tests pass
• Reference related Issues
• Up-to-date CHANGELOG.md
• Add type hints in created/changed code
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there spezifications? Are they satisfied?

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src/caosdb/common/administration.py

@@ -26,6 +26,9 @@
 
 """missing docstring."""
 
+import re
+import string
+import random
 from caosdb.common.utils import xml2str
 from caosdb.connection.connection import get_connection
 from caosdb.exceptions import (EntityDoesNotExistError, HTTPClientError,
@@ -56,7 +59,8 @@ def set_server_property(key, value):
         con._form_data_request(method="POST", path="_server_properties",
                                params={key: value}).read()
     except EntityDoesNotExistError:
-        raise ServerConfigurationException("Debug mode in server is probably disabled.") from None
+        raise ServerConfigurationException(
+            "Debug mode in server is probably disabled.") from None
 
 
 def get_server_properties():
@@ -71,9 +75,11 @@ def get_server_properties():
     """
     con = get_connection()
     try:
-        body = con._http_request(method="GET", path="_server_properties").response
+        body = con._http_request(
+            method="GET", path="_server_properties").response
     except EntityDoesNotExistError:
-        raise ServerConfigurationException("Debug mode in server is probably disabled.") from None
+        raise ServerConfigurationException(
+            "Debug mode in server is probably disabled.") from None
 
     xml = etree.parse(body)
     props = dict()
@@ -108,6 +114,39 @@ def get_server_property(key):
     return get_server_properties()[key]
 
 
+def generate_password(length: int):
+    """Create a random password that fulfills the security requirements
+
+    Parameters
+    ----------
+    length : int
+        Length of the generated password.  Has to be greater than 7.
+
+    Returns
+    -------
+    password : string
+        Generated random password of the given length
+
+    Raises
+    ------
+    ValueError:
+        If the length is less than 8.
+    """
+    minimum_password_length = 8
+    if length < minimum_password_length:
+        raise ValueError("CaosDB passwords have to be at least {} characters.".format(
+            minimum_password_length))
+    sample_letters = string.ascii_letters + string.digits + "!#$%*+-/:;?_"
+    password = ''.join((random.choice(sample_letters) for i in range(length)))
+
+    while not re.match(r"(?=.*[A-Z])(?=.*[a-z])(?=.*\d)(?=.*[\W_]).{8,}",
+                       password):
+        password = ''.join((random.choice(sample_letters)
+                            for i in range(length)))
+
+    return password
+
+
 def _retrieve_user(name, realm=None, **kwargs):
     con = get_connection()
     try: