promptshield

promptshield is a drop-in classifier that screens text prompts for CSAM-generation intent before they reach a text-to-image or text-to-video model, so abusive requests are blocked before a single GPU cycle is spent. It is a Python library for self-hosted generation stacks that ship with no input-side defense of their own.

Install

pip install digitalharm-promptshield

The distribution is digitalharm-promptshield but imported as promptshield (e.g. import promptshield).

What it does

• Exposes a one-line guard(prompt, negative_prompt=None) that returns a structured verdict: allow, block, or review, with a calibrated score and the list of matched signals.
• Runs a fast deterministic first stage — homoglyph, leetspeak, and whitespace normalization plus a curated lexicon — on CPU, no GPU required.
• Keys on the conjunction of a minor-indicator concept and a sexual concept, so neither alone trips the gate, which keeps false positives down.
• Handles negative-prompt evasion, such as adult or mature stuffed into negatives to disguise intent.
• Logs no prompt content by default, with an optional hash-only audit trail for NCMEC-reporting integrations.
• Is one input-side layer of a defense-in-depth stack, never a substitute for an output classifier plus known-CSAM hash matching.

Quickstart

import promptshield

verdict = promptshield.guard(prompt, negative_prompt=negative_prompt)

if verdict.action == "block":
    raise ValueError("Prompt rejected by promptshield")

# verdict.action is one of: "allow", "block", "review"
print(verdict.score, verdict.matched_signals)

A review verdict is for borderline prompts you want to route to a human or a stricter policy rather than allow or block outright.

Status

Pre-release: the first PyPI publish is still pending, so pip install digitalharm-promptshield is not live yet. The deterministic first stage, the fine-tuned ONNX classifier, the framework adapters, and the adversarial test suite are still in progress toward v0.1 — pin versions and expect APIs to move before the first stable release.

Source

packages/promptshield