[FEAT]: Implement PyRIT converter_bridge for PayloadConverter protocol (#69)

rampart/pyrit_bridge/__init__.py

@@ -3,6 +3,10 @@
 
 """PyRIT integration bridge."""
 
+from rampart.pyrit_bridge.converter_bridge import (
+    PyRITConverterBridge,
+    adapt_converter,
+)
 from rampart.pyrit_bridge.llm_bridge import (
     create_prompt_target,
     send_generation_request_async,
@@ -11,6 +15,8 @@
 )
 
 __all__ = [
+    "PyRITConverterBridge",
+    "adapt_converter",
     "create_prompt_target",
     "send_generation_request_async",
     "send_judge_request_async",

rampart/pyrit_bridge/converter_bridge.py

@@ -0,0 +1,82 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+"""PyRIT converter bridge — adapt PyRIT PromptConverters to RAMPART PayloadConverter.
+
+Enables RAMPART to leverage PyRIT's rich library of prompt converters
+(Base64, Atbash, Caesar, Unicode, ROT13, Leetspeak, etc.) while adhering
+to RAMPART's ``PayloadConverter`` protocol.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from rampart.core.types import Payload, PayloadFormat
+
+if TYPE_CHECKING:
+    from pyrit.prompt_converter import PromptConverter
+
+
+class PyRITConverterBridge:
+    """Adapt a PyRIT ``PromptConverter`` to RAMPART's ``PayloadConverter`` protocol.
+
+    Runs the underlying PyRIT prompt converter on the payload's text content,
+    returning a new ``Payload`` with the transformed text, preserved identifier,
+    format set to TEXT, and updated metadata tagging the converter.
+
+    Attributes:
+        converter: The wrapped PyRIT PromptConverter instance.
+    """
+
+    def __init__(self, converter: PromptConverter) -> None:
+        """Initialize with a PyRIT PromptConverter instance.
+
+        Args:
+            converter (PromptConverter): The PyRIT PromptConverter to adapt.
+        """
+        self.converter = converter
+        self._name = converter.__class__.__name__
+
+    async def convert_async(self, *, payload: Payload) -> Payload:
+        """Transform a text payload using the underlying PyRIT converter.
+
+        Args:
+            payload (Payload): A text-format payload to convert.
+
+        Returns:
+            Payload: A new payload with transformed text content.
+
+        Raises:
+            ValueError: If the payload format is not a text format.
+        """
+        if not payload.format.is_text:
+            msg = f"{self._name} requires a text payload, got {payload.format.value}."
+            raise ValueError(msg)
+
+        result = await self.converter.convert_async(
+            prompt=payload.content,
+            input_type="text",
+        )
+
+        metadata = {**payload.metadata, "converter": self._name}
+
+        return Payload(
+            content=result.output_text,
+            id=payload.id,
+            format=PayloadFormat.TEXT,
+            artifact=None,
+            metadata=metadata,
+        )
+
+
+def adapt_converter(converter: PromptConverter) -> PyRITConverterBridge:
+    """Adapt a PyRIT PromptConverter to a RAMPART PayloadConverter.
+
+    Args:
+        converter (PromptConverter): The PyRIT PromptConverter to wrap.
+
+    Returns:
+        PyRITConverterBridge: An adapter fulfilling the PayloadConverter protocol.
+    """
+    return PyRITConverterBridge(converter)

tests/unit/pyrit_bridge/test_converter_bridge.py

@@ -0,0 +1,107 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT license.
+
+"""Tests for the PyRIT converter bridge.
+
+Validates adaptation of PyRIT PromptConverters to RAMPART's
+PayloadConverter protocol and verifies text transformation semantics.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+import pytest
+from pyrit.prompt_converter import Base64Converter, ROT13Converter
+
+from rampart.core.converter import PayloadConverter
+from rampart.core.types import Payload, PayloadFormat
+from rampart.pyrit_bridge.converter_bridge import (
+    PyRITConverterBridge,
+    adapt_converter,
+)
+
+if TYPE_CHECKING:
+    from pathlib import Path
+
+
+class TestPyRITConverterBridgeProtocol:
+    """Verify PyRITConverterBridge satisfies PayloadConverter protocol."""
+
+    def test_implements_payload_converter_protocol(self) -> None:
+        bridge = PyRITConverterBridge(Base64Converter())
+        assert isinstance(bridge, PayloadConverter)
+
+    def test_adapt_converter_helper(self) -> None:
+        bridge = adapt_converter(ROT13Converter())
+        assert isinstance(bridge, PayloadConverter)
+        assert isinstance(bridge, PyRITConverterBridge)
+
+
+class TestPyRITConverterBridgeConversion:
+    """Verify conversion behavior across PyRIT converters."""
+
+    @pytest.mark.asyncio
+    async def test_base64_conversion(self) -> None:
+        bridge = adapt_converter(Base64Converter())
+        payload = Payload(
+            content="Ignore instructions",
+            id="test-p1",
+            format=PayloadFormat.TEXT,
+            metadata={"source": "unit_test"},
+        )
+
+        result = await bridge.convert_async(payload=payload)
+
+        assert result.id == "test-p1"
+        assert result.content == "SWdub3JlIGluc3RydWN0aW9ucw=="
+        assert result.format == PayloadFormat.TEXT
+        assert result.artifact is None
+        assert result.metadata["source"] == "unit_test"
+        assert result.metadata["converter"] == "Base64Converter"
+
+    @pytest.mark.asyncio
+    async def test_rot13_conversion(self) -> None:
+        bridge = adapt_converter(ROT13Converter())
+        payload = Payload(
+            content="Hello World",
+            id="test-p2",
+            format=PayloadFormat.TEXT,
+        )
+
+        result = await bridge.convert_async(payload=payload)
+
+        assert result.id == "test-p2"
+        assert result.content == "Uryyb Jbeyq"
+        assert result.format == PayloadFormat.TEXT
+        assert result.metadata["converter"] == "ROT13Converter"
+
+    @pytest.mark.asyncio
+    async def test_empty_content_conversion(self) -> None:
+        bridge = adapt_converter(Base64Converter())
+        payload = Payload(
+            content="",
+            id="test-empty",
+            format=PayloadFormat.TEXT,
+        )
+
+        result = await bridge.convert_async(payload=payload)
+
+        assert result.id == "test-empty"
+        assert result.content == ""
+        assert result.format == PayloadFormat.TEXT
+
+    @pytest.mark.asyncio
+    async def test_non_text_payload_raises_value_error(self, tmp_path: Path) -> None:
+        artifact = tmp_path / "test.docx"
+        artifact.touch()
+        bridge = adapt_converter(Base64Converter())
+        payload = Payload(
+            content="Binary content",
+            id="test-docx",
+            format=PayloadFormat.DOCX,
+            artifact=artifact,
+        )
+
+        with pytest.raises(ValueError, match="requires a text payload"):
+            await bridge.convert_async(payload=payload)