Security

The claim secret is generated in the browser, kept in the URL fragment, and hashed before it reaches the contract. The optional note is encrypted in the browser with AES-GCM; the contract stores only ciphertext. Gift records, token contracts, amounts, and transfers are public onchain.

Sponsored claims require a NEP-413 signature bound to the configured contract, gift, recipient account, secret commitment, timestamp, and nonce. The optional callback URL may be absent, as with Meteor, or match the exact claim-page URL; other signed callback URLs are refused. The API verifies the signature and confirms the public key is currently a full-access key of that account. The relayer's NEAR key is server-only. The contract restricts claims to the configured relayer and marks each claim nonce used before scheduling a token transfer.

The claim transaction reveals the secret, so observers can decrypt the note after redemption. Session storage retains the recipient's secret for reloads in the current tab. The relayer is trusted to verify wallet ownership and may sponsor recipient token registration up to 0.1 testnet NEAR; allowlist only trusted tokens.

The API enforces same-origin requests, a strict body limit, and a per-process request rate limit. The current rate limiter is not shared across instances; run one app instance or add distributed rate limiting before scaling.

The Rust contract has local unit tests, but it has not received an external security audit. Keep this deployment on testnet and use test tokens only.