[emdin]

Summary

cast igra verify-bundle-integral rejects manifests whose bundleIdentity.payloadVersion is 3, because their integral payload is canonicalized with RFC 8785 JCS (rfc8785-jcs-utf8):

Error: unsupported bundleIntegral.canonicalization: rfc8785-jcs-utf8

This adds JCS support and hardens how the verifier reads manifests. No signing, building or broadcasting code is touched.

JCS support

• Object keys are ordered by UTF-16 code units (RFC 8785 section 3.2.3). Strings reuse serde_json escaping, which matches section 3.2.2.2.
• Numbers are limited to integers with |n| <= 2^53 - 1, whose ES6 form is the plain decimal. Anything else is refused rather than hashed in a form the producer may not have used.

payloadVersion selects the canonicalization

• 1 and 2, or no bundleIdentity: the legacy canonicalization, unchanged. 3: JCS.
• A declared canonicalization that does not match, an unknown payloadVersion, or a bundleIdentity that is not an object is refused instead of falling back to the legacy canonicalization.

Strict manifest parsing

verify-bundle-integral hashes serde_json's view of the manifest, which can differ from what other JSON parsers read. The new parse_bundle_manifest refuses:

• Duplicate object keys. serde_json keeps the last one, while other parsers may keep the first, and RFC 8785 requires I-JSON, which forbids them. Before this change, a legacy manifest with a conflicting duplicate "kind" key injected at the start verified as ok.
• Keys starting with $serde_json::private::. With the arbitrary_precision and raw_value features enabled in this workspace, serde_json reads such an object as a number or as embedded JSON.
• Numbers that are not 64-bit integers. serde_json passes them through the same reserved key, and manifests only carry integers.

Test plan

• 14 unit tests in igra_bundle cover:
  • the RFC 8785 section 3.2.3 sorting example and the section 3.2.2 string-escaping example;
  • a synthetic JCS manifest whose expected hash comes from an independent Python RFC 8785 implementation;
  • tamper detection and the number subset;
  • payloadVersion pairing and unknown versions;
  • duplicate, reserved and escaped keys, non-integer numbers, and a round trip.
• Mutation check: each new guard was removed in turn, and its test failed.
• cargo test --locked -p foundry-common --lib: 99 passed, 2 ignored.
• cargo clippy --all-targets on foundry-common (all features) and cast reports no findings in the changed files.
• The changed code is clean under nightly rustfmt.
• End to end with cargo build --locked -p cast --no-default-features, running verify-bundle-integral on every locally available bundle manifest:
  • every legacy manifest verifies, with output byte-identical to the previous binary;
  • every payloadVersion 3 manifest verifies, where the previous binary rejected it;
  • hostile copies are rejected: duplicate key, reserved key, non-integer number, tampered hash, unknown payloadVersion, and canonicalization downgrade.

CI failures that already exist on the base branch and are not addressed here:

• cargo deny (dependency advisories and licenses);
• clippy -Dwarnings findings in other files of both crates;
• rustfmt differences in other code, including import grouping and doc comments already present in crates/cast/src/cmd/igra.rs.

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