How-to: PII masking¶

Aegis's PII pack masks personally identifiable information in ingress messages and unmasks it in the model's response — the model never sees real PII.

Install¶

pip install "aegis-gateway[pii]"
python -m spacy download en_core_web_sm

Configure¶

providers:
  main:
    type: anthropic
    api_key: secret://env/ANTHROPIC_API_KEY

guardrails:
  pii:
    pack: aegis.pii
    mode: mask

pipeline:
  ingress: [pii]
  egress: [pii.unmask]

routes:
  default:
    provider: main

The ingress stage replaces detected entities with placeholders like <PERSON_1>, <EMAIL_ADDRESS_1>. The egress stage substitutes them back in the response using the per-run mask map (never serialised into model-visible messages).

Supported entity types¶

The PII pack uses Presidio + the en_core_web_sm spaCy model. Detected by default:

PERSON, EMAIL_ADDRESS, PHONE_NUMBER, LOCATION, CREDIT_CARD, IBAN_CODE, IP_ADDRESS, URL, US_SSN, DATE_TIME

Audit events¶

Every masking and unmasking operation emits an event into the run's event log. Query it via:

curl http://localhost:8000/v1/audit

Testing without PII installed¶

In unit tests, use FakeProvider and skip PII installation:

import pytest

pytest.importorskip("presidio_analyzer", reason="[pii] extra not installed")