From 343da7f87d986e2aa4dbe8df2d81061fac3bccda Mon Sep 17 00:00:00 2001
From: Victor Kuznetsov <kuznetsov.va@gmail.com>
Date: Fri, 28 Aug 2026 20:00:18 -0700
Subject: [PATCH] Add a synthetic Ideogram C2PA attribution fixture

A throwaway test CA with leaf subject CN=Ideogram, Inc signs a flat PNG
carrying a trainedAlgorithmicMedia claim. The fixture exercises the
issuer-to-platform attribution end to end through the real reader and pins
the second dimension the project separates: attribution names Ideogram
while signer trust stays untrusted. Recipe documented in the fixtures
README; no keys, vendor bytes, or user uploads are committed.
---
 data/fixtures/README.md                    |  20 ++++++++++++++++++++
 data/fixtures/provenance/ideogram-c2pa.png | Bin 0 -> 43836 bytes
 tests/test_identify.py                     |  12 ++++++++++++
 3 files changed, 32 insertions(+)
 create mode 100644 data/fixtures/provenance/ideogram-c2pa.png

diff --git a/data/fixtures/README.md b/data/fixtures/README.md
index c71559f..47176b6 100644
--- a/data/fixtures/README.md
+++ b/data/fixtures/README.md
@@ -13,3 +13,23 @@ example from [`adobe/trustmark`](https://github.com/adobe/trustmark) at commit
 - SHA-256: `e58c5825ed7e5d9fb04710ea541b61bd55879cad65554c0d46260aa24b3d0755`
 - Expected signal: TrustMark Variant P, schema 1
 - License: MIT, reproduced in `../licenses/adobe-trustmark-MIT.txt`
+
+
+## Ideogram C2PA attribution
+
+`ideogram-c2pa.png` is a SYNTHETIC signed manifest, not a vendor download: a
+64x64 flat PNG carrying a C2PA claim (`trainedAlgorithmicMedia`,
+`claim_generator "Ideogram/3.0"`) signed by a throwaway test CA whose leaf
+certificate subject is `O=Ideogram, Inc, CN=Ideogram, Inc`. It exercises the
+issuer-to-platform ATTRIBUTION path end to end through the real reader; the
+signer is deliberately untrusted (no trust anchors ship), which is also the
+fixture's second assertion: attribution and signer trust are separate
+dimensions.
+
+- Expected signal: C2PA, platform `Ideogram`, `ai_from_metadata` True
+- Expected signer: `untrusted` (test CA; attribution must not imply trust)
+- Recipe (no keys are committed): create a CA and an ES256 leaf with
+  `digitalSignature` key usage and subject `CN=Ideogram, Inc`, then
+  `c2pa.Builder.from_json(...).sign_file(png, out, Signer.from_info(
+  C2paSignerInfo(b"es256", leaf_pem + ca_pem, pkcs8_key, None)))`.
+- No user upload and no Ideogram artifact contributes pixels or bytes.
diff --git a/data/fixtures/provenance/ideogram-c2pa.png b/data/fixtures/provenance/ideogram-c2pa.png
new file mode 100644
index 0000000000000000000000000000000000000000..d3d47d0f2c565dce084832884c02e2e8fa371278
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diff --git a/tests/test_identify.py b/tests/test_identify.py
index 4b1d002..e1156b0 100644
--- a/tests/test_identify.py
+++ b/tests/test_identify.py
@@ -1489,6 +1489,18 @@ class TestVendorOf:
         assert _vendor_of("Eleven Labs Inc.") == "ElevenLabs"
         assert _vendor_of("Ideogram") == "Ideogram"
 
+    def test_ideogram_fixture_attributed_end_to_end(self):
+        # Committed synthetic manifest signed by a test CA with CN "Ideogram, Inc":
+        # attribution must name the platform while signer trust stays untrusted.
+        # Reachability against the fixture, not a synthesized status set.
+        fixture = Path(__file__).resolve().parents[1] / "data" / "fixtures" / "provenance" / "ideogram-c2pa.png"
+        if not fixture.exists():  # the sdist ships no data/
+            pytest.skip("provenance fixture not present")
+        report = identify(fixture, check_visible=False, check_invisible=False)
+        assert report.ai_from_metadata is True
+        assert report.platform == "Ideogram"
+        assert any("Ideogram" in w for w in report.watermarks)
+
     def test_ideogram_issuer_attributed(self):
         # Corpus evidence 2026-08-08: four uploads signed "Ideogram, Inc" read as
         # unknown-signer C2PA with no platform. The issuer token is the org prefix.