Canonical forms

The canonical form is chosen by the object's version field, so a verifier never guesses.

JCS (RFC 8785) — everything from receipt v2 onward

Implementation: core/jcs.php (manav_jcs), js/jcs.js (manavJcs), packages/verify-py/manav_verify/jcs.py. Vectors: tests/vectors/jcs/ (the six RFC 8785 test files plus 37 manav vectors); php tests/jcs-vectors.php, node tests/jcs-vectors.mjs; differential test over generated values in tests/run.php group 10.

Rules on top of RFC 8785:

• Key order is by UTF-16 code unit (RFC 8785 §3.2.3). PHP's strcmp sorts UTF-8 bytes, which diverges for non-BMP characters: for the keys U+E000 and U+10000, byte order gives E000, 10000; JCS gives 10000, E000, because the surrogate pair starts at D800. core/jcs.php converts keys to UTF-16BE before comparing. JavaScript's default sort already compares code units.
• Integers only. Floats are rejected (float_not_permitted) rather than serialised, so no two implementations can disagree about ECMAScript number formatting. Integers must lie within ±(2^53 − 1). Money is a fixed-precision string with an explicit currency.
• Strings (rule R5): NFC-normalised; bidi controls, zero-width and other default-ignorable code points, BOM, soft hyphen, variation selectors and tag characters are rejected (r5_unsafe_string:invisible_or_bidi); C0/C1 controls are rejected (:control); mixing scripts among letters inside one string is rejected (:mixed_script), except Latin with CJK.
• Empty object vs empty array is preserved: PHP callers pass objects as stdClass (manav_to_object, or json_decode(…, false)).

Signing input for hybrid-signed objects

M = UTF8(object["v"]) || 0x0A || JCS(object without "sig"). The type tag inside the signed bytes prevents cross-type replay (a lease signature can never be presented as a receipt signature). Receipt v2 uses the tag manav-receipt/2 even though its stored v is the integer 2.

Legacy v1 form — frozen

core/canonical.php::manav_canonical_encode_legacy_v1: recursive ksort (byte order) + json_encode(JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES). It is not RFC 8785 and MUST NOT be used for anything new. It exists so that objects signed before 2026-09 keep verifying (tests/corpus/v1, group 17). The v1 revocation list at /v2/revoked also uses it.