Module sync 

Sync verification primitives for Zcash light clients.

Pure verification logic with no IO, no wallet state, and no network calls. Every function takes data in and returns a verdict. This is the core of the trust model: the server provides claims, these functions verify them against cryptographic proofs anchored to the hardcoded activation block hash.

Verification flow

header proof bytes ─→ verify_header_proof() ─→ ProvenRoots
                                                   │
                 ┌─────────────────────────────────┼──────────────────────┐
                 │                                 │                      │
                 ▼                                 ▼                      ▼
  verify_commitment_proofs()        verify_nullifier_proofs()   verify_actions_commitment()
  (received notes exist)            (spent/unspent status)      (block action integrity)

All verification functions return Result<T, ZyncError>. An Err means the server is lying or compromised. The caller MUST abort the sync and not persist any data from this session.

Memo extraction

extract_enc_ciphertext parses raw V5 transaction bytes to find the 580-byte encrypted ciphertext for a specific action. Memo decryption itself requires orchard key types (version-sensitive), so callers handle try_note_decryption directly using their own orchard dependency.

Structs

CommitmentProofData

Commitment proof from a server, ready for verification.

CrossVerifyTally

Result of cross-verifying a block hash against multiple endpoints.

NullifierProofData

Nullifier proof from a server, ready for verification.

ProvenRoots

Proven NOMT roots extracted from the ligerito header proof. These are the roots that NOMT merkle proofs must verify against.

Functions

chain_actions_commitment

Compute running actions commitment for a sequence of blocks.

extract_enc_ciphertext

Extract the 580-byte enc_ciphertext for an action matching cmx+epk from raw tx bytes.

hashes_match

Compare two block hashes, accounting for LE/BE byte order differences between native gRPC lightwalletd (BE display order) and zidecar (LE internal).

verify_actions_commitment

Verify the running actions commitment chain against the proven value.

verify_commitment_proofs

Verify a batch of commitment proofs against proven roots.

verify_header_proof

Validate a header proof and extract proven NOMT roots.

verify_nullifier_proofs

Verify a batch of nullifier proofs against proven roots.