Allow server admins to define and enforce a password policy (MSC2000). (#7118)

docs/sample_config.yaml

@@ -1482,6 +1482,41 @@ password_config:
    #
    #pepper: "EVEN_MORE_SECRET"
 
+   # Define and enforce a password policy. Each parameter is optional.
+   # This is an implementation of MSC2000.
+   #
+   policy:
+      # Whether to enforce the password policy.
+      # Defaults to 'false'.
+      #
+      #enabled: true
+
+      # Minimum accepted length for a password.
+      # Defaults to 0.
+      #
+      #minimum_length: 15
+
+      # Whether a password must contain at least one digit.
+      # Defaults to 'false'.
+      #
+      #require_digit: true
+
+      # Whether a password must contain at least one symbol.
+      # A symbol is any character that's not a number or a letter.
+      # Defaults to 'false'.
+      #
+      #require_symbol: true
+
+      # Whether a password must contain at least one lowercase letter.
+      # Defaults to 'false'.
+      #
+      #require_lowercase: true
+
+      # Whether a password must contain at least one lowercase letter.
+      # Defaults to 'false'.
+      #
+      #require_uppercase: true
+
 
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