The Proof secret.
Secret object.
Layer 1 validation: Checks NUT-10 structure, rejects duplicate P2PK tag keys, and validates sigflag value. Does NOT validate cross-tag semantics (e.g. n_sigs <= pubkeys) — use verifyP2PKSpendingConditions for full semantic validation.
Parse a P2PK Secret and validate NUT-10 shape and NUT-11 tag-level constraints.