Add try_recover_key; handle the recover_key -1 sentinel#59
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The host recover_key intrinsic returns the required public-key size on success and a negative code on a contract-observable failure (bad/empty/truncated signature, unactivated or unknown variant, recovery-math failure). The CDT wrappers never accounted for the negative code: - recover_key assigned the int result straight into size_t, so a -1 became SIZE_MAX, fell into the large-buffer branch, and ran malloc(SIZE_MAX) + a datastream over an invalid pointer -- a WASM trap on any unrecoverable signature. Add try_recover_key, returning std::optional<public_key>: std::nullopt when the host signals failure, the key otherwise. Intended for callers that accept untrusted, user-submitted signatures and must not abort the transaction on bad input (e.g. consensus inline-action handlers). Harden the by-value recover_key: a negative host code is now a clean check() abort instead of the SIZE_MAX path. Both functions share one recover_key_impl so the recovery/large-buffer logic has a single implementation. The large-buffer branch now also checks the allocation result and the refill return code instead of trusting them blindly. crypto_tests gains try_recover_key_test, which stubs the host recover_key via set_intrinsic and exercises both wrappers end to end: a non-negative result yields the recovered key; a negative result yields std::nullopt from try_recover_key and a clean abort from recover_key. The recovered-key check is guarded so a regression reports a clean failure rather than dereferencing an empty optional. The host-side non-throwing behavior shipped in wire-sysio (recover_key returns -1 on contract-observable failure); this is the CDT-side half that lets contracts actually consume it without trapping. The host's subjective WebAuthn variable-size guard still rejects the transaction before the contract observes anything and is deliberately not maskable.
heifner
changed the title
capi_checksum256 is declared alignas(16); the byte-array storage from checksum256::extract_as_byte_array() is alignment 1. reinterpret_cast'ing it to capi_checksum256* is a misaligned-pointer access (UB; can trap or miscompile on strict / native targets, and the native unit tests now exercise this path). recover_key_impl and assert_recover_key now memcpy the digest into a properly aligned local and pass that to the host intrinsics.
huangminghuang
approved these changes
May 18, 2026
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The host recover_key intrinsic returns the required public-key size on success and a negative code on a contract-observable failure (bad/empty/truncated signature, unactivated or unknown variant, recovery-math failure). The CDT wrappers never accounted for the negative code:
Add try_recover_key, returning std::optional<public_key>: std::nullopt when the host signals failure, the key otherwise. Intended for callers that accept untrusted, user-submitted signatures and must not abort the transaction on bad input (e.g. consensus inline-action handlers).
Harden the by-value recover_key: a negative host code is now a clean check() abort instead of the SIZE_MAX path. Both functions share one recover_key_impl so the recovery/large-buffer logic has a single implementation. The large-buffer branch now also checks the allocation result and the refill return code instead of trusting them blindly.
crypto_tests gains try_recover_key_test, which stubs the host recover_key via set_intrinsic and exercises both wrappers end to end: a non-negative result yields the recovered key; a negative result yields std::nullopt from try_recover_key and a clean abort from recover_key. The recovered-key check is guarded so a regression reports a clean failure rather than dereferencing an empty optional.
The host-side non-throwing behavior shipped in wire-sysio (recover_key returns -1 on contract-observable failure); this is the CDT-side half that lets contracts actually consume it without trapping. The host's subjective WebAuthn variable-size guard still rejects the transaction before the contract observes anything and is deliberately not maskable.
Pairs with wire-sysio's non-throwing recover_key (PR #314). Follow-up on the wire-sysio side: verify_uic_signature switches to try_recover_key and the part3 recover_key_nothrow host intrinsic is dropped, once master lands in the OPP line.