FIX MathObfuscationConverter: write the multiplication explicitly for digits

pyrit/converter/math_obfuscation_converter.py

@@ -23,6 +23,9 @@ class MathObfuscationConverter(Converter):
     The transformation follows these rules:
 
     * Each non-space character becomes one algebraic line.
+    * Numeric characters, such as digits, superscripts and fractions, write the
+      multiplication explicitly, as in `5 = 8*5 - 7*5`, because `85 - 75` would
+      read as two-digit numbers.
     * Space characters are represented as blank output lines.
     * Newline characters are preserved as blank output lines.
 
@@ -150,7 +153,8 @@ async def convert_async(
                 continue
 
             n = rng.randint(self._min_n, self._max_n)
-            line = f"{ch} = {n}{ch} - {n - 1}{ch}"
+            multiply = "*" if ch.isnumeric() else ""
+            line = f"{ch} = {n}{multiply}{ch} - {n - 1}{multiply}{ch}"
 
             # Add hint inline after the first equation
             if not first_equation_added and self._hint:

tests/unit/converter/test_math_obfuscation_converter.py

@@ -3,6 +3,7 @@
 
 import asyncio
 import random
+import re
 
 import pytest
 
@@ -32,6 +33,40 @@ def test_math_obfuscation_deterministic_small(input_text, expected_output):
     assert result.output_text == expected_output
 
 
+@pytest.mark.parametrize("digit", list("0123456789") + ["\u0665"])
+def test_math_obfuscation_digit_lines_are_true_identities(digit):
+    converter = MathObfuscationConverter(min_n=2, max_n=9, rng=random.Random(3), hint="", suffix="")
+
+    result = asyncio.run(converter.convert_async(prompt=digit * 20))
+
+    for line in result.output_text.splitlines():
+        match = re.fullmatch(rf"{digit} = (\d)\*{digit} - (\d)\*{digit}", line)
+        assert match is not None, line
+        value = int(digit)
+        assert int(match.group(1)) * value - int(match.group(2)) * value == value
+        assert int(match.group(1)) - int(match.group(2)) == 1
+
+
+@pytest.mark.parametrize("character", ["\u00b2", "\u2083", "\u00bd", "\u2167", "\u4e94"])
+def test_math_obfuscation_other_numeric_characters_use_explicit_multiplication(character):
+    converter = MathObfuscationConverter(min_n=2, max_n=9, rng=random.Random(3), hint="", suffix="")
+
+    result = asyncio.run(converter.convert_async(prompt=character * 20))
+
+    for line in result.output_text.splitlines():
+        match = re.fullmatch(rf"{character} = (\d)\*{character} - (\d)\*{character}", line)
+        assert match is not None, line
+        assert int(match.group(1)) - int(match.group(2)) == 1
+
+
+def test_math_obfuscation_digits_and_letters_in_one_prompt():
+    converter = MathObfuscationConverter(rng=random.Random(1), hint="", suffix="")
+
+    result = asyncio.run(converter.convert_async(prompt="A1"))
+
+    assert result.output_text == "A = 4A - 3A\n1 = 3*1 - 2*1"
+
+
 def test_math_obfuscation_spaces_and_newlines():
     """Spaces -> blank lines, newlines -> blank lines."""
     rng = random.Random(1)