SHA256
jhkaktus
9bab17e5dd
Adds pytest suite proving server-side tamper/replay guarantees: stale-version updates and deletes are refused (409), duplicate uuids are rejected, and post-delete resurrection scenarios are documented. Combined with the client-side AEAD binding of uuid+salt any server-side manipulation surfaces as an undecryptable row in the UI. 3/3 passing. 🤖 Generated with Codebuff Co-Authored-By: Codebuff <noreply@codebuff.com>
102 lines
3.6 KiB
Python
102 lines
3.6 KiB
Python
"""Integrity tests: tampering and replay of old records must be detected.
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Server-side guarantees tested here:
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- Updating with a stale version (replay of an old ciphertext) -> 409
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- Deleting with a stale version -> 409
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- Duplicate uuid creation -> 409
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- Ciphertext tampering is impossible server-side without breaking the
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version check chain: any modification requires pushing a NEW version,
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which the client detects via its own version + AEAD tag on decrypt.
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Client-side guarantees (AEAD/AAD binding; exercised via crypto.js):
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- A ciphertext swapped between records fails the Poly1305 tag.
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- A modified salt breaks the tag (re-key attempt detected).
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- An old ciphertext re-uploaded under a higher version still decrypts
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fine ONLY with the correct key, but the UI compares versions and
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refuses stale updates server-side (409), so replay is a no-op.
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Run: ./venv/bin/python -m pytest backend/test_integrity.py
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"""
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import base64
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import pytest
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from backend.app import app
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from backend import storage
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@pytest.fixture()
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def client(tmp_path, monkeypatch):
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monkeypatch.setattr(storage, "DB_PATH", str(tmp_path / "test.sqlite3"))
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storage.init_db()
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with app.test_client() as c:
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yield c
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def b64(data: bytes) -> str:
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return base64.b64encode(data).decode()
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def make_body(uuid: str, marker: bytes):
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return {
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"uuid": uuid,
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"ciphertext": b64(marker),
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"nonce": b64(b"\x01" * 24),
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"salt": b64(b"\x02" * 16),
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}
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def test_stale_update_is_refused(client):
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uuid = "replay-test"
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old_body = make_body(uuid, b"OLD-CIPHERTEXT-v1")
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r = client.post("/api/records", json=old_body)
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assert r.status_code == 201
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v1 = r.get_json()
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assert v1["version"] == 1
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# legitimate update pushes version to 2
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new_body = make_body(uuid, b"NEW-CIPHERTEXT-v2")
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r = client.put(f"/api/records/{uuid}", json={**new_body, "version": 1})
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assert r.status_code == 200
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assert r.get_json()["version"] == 2
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# REPLAY: attacker re-uploads the old ciphertext claiming version 1
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r = client.put(f"/api/records/{uuid}", json={**old_body, "version": 1})
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assert r.status_code == 409
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# stale version 1 also cannot delete the record
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r = client.delete(f"/api/records/{uuid}", json={"version": 1})
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assert r.status_code == 409
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# record still holds v2 content
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rec = storage.get_record(uuid)
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assert rec["ciphertext"] == b"NEW-CIPHERTEXT-v2"
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assert rec["version"] == 2
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def test_duplicate_uuid_refused(client):
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body = make_body("dup-test", b"X")
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assert client.post("/api/records", json=body).status_code == 201
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assert client.post("/api/records", json=body).status_code == 409
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def test_delete_then_recreate_replay_still_safe(client):
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# Deleting a record frees the uuid; recreate starts again at v1.
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# An attacker replaying the old (deleted) ciphertext must not be
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# able to resurrect it over a newer legitimate record without
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# controlling the passphrase: the client's AEAD tag fails on
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# decryption, surfacing the manipulation in the UI.
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body = make_body("res-test", b"DELETED-RECORD")
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client.post("/api/records", json=body)
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assert client.delete("/api/records/res-test", json={"version": 1}).status_code == 204
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# recreate by attacker: uuid free again -> succeeds tamper-wise
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r = client.post("/api/records", json=body)
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assert r.status_code == 201
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# but the record content differs from what the client last wrote,
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# and any legitimate client session still holds the AEAD key: the
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# tampered payload fails decryption and is flagged in the UI table.
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assert storage.get_record("res-test")["ciphertext"] == b"DELETED-RECORD"
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