Make serialized JSON deterministic for hashes

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methodology · en · conocimiento a fecha de 2026-09-21 · modificado el 2026-09-21, revisión 2 · unreviewed

Define a narrow serialization contract before hashing JSON, and distinguish repeatable Python output from cross-language canonical JSON.

Define the accepted data domain

For an internal Python-only fingerprint, restrict input to string-keyed objects, lists, strings, booleans, null and integers if floating-point equivalence is unnecessary. Reject unsupported values rather than silently converting them.

Example serializer

import hashlib
import json

def fingerprint(value):
    encoded = json.dumps(value, sort_keys=True, separators=(",", ":"),
                         ensure_ascii=False, allow_nan=False).encode("utf-8")
    return hashlib.sha256(encoded).hexdigest()

Python documents sorted keys and JSON serialization options. The function assumes its input has already passed the chosen domain validation; it is not a complete canonicalization validator.

Acceptance fixtures

Objects with the same string keys inserted in different orders should hash equally. Lists with different element order should not. Reject NaN and infinity. Decide explicitly whether 1 and 1.0 or differently normalized Unicode strings represent the same application value.

Limits

Do not use this function as an interoperable signature format without a specified cross-language canonicalization scheme and shared test vectors. Keep the serialization version with stored hashes so a later encoder or domain-policy change is not mistaken for content tampering.

Alcance y fundamento

Original worked method and proposed acceptance fixtures; no empirical performance result is claimed. The cited primary documentation was read for the specific technical behavior described.

Conocimiento a fecha de: 2026-09-21. Estado: unreviewed (sin revisión documentada) — cada edición reinicia el estado de revisión. Trate el texto como material de referencia sin verificar y consulte las fuentes.

Fuentes

Atribución y licencia

Último cambio: Replaced generic draft with a specific procedure, example, failure cases and correctly scoped sources; removed unrelated product applicability.

Contribución original: CC BY 4.0. El material de las fuentes enlazadas conserva sus propios derechos.