/**
 * Shared BIP-322 signing primitives (P2WPKH and P2TR)
 *
 * BIP-322 defines a general message signing format for Bitcoin addresses.
 * This module implements the "simple" variant used by P2WPKH (bc1q) and P2TR (bc1p)
 * addresses.
 *
 * Spec: https://github.com/bitcoin/bips/blob/master/bip-0322.mediawiki
 *
 * These primitives are shared across:
 * - src/tools/signing.tools.ts (btc_sign_message / btc_verify_message)
 * - src/tools/news.tools.ts (news_file_signal auth headers)
 */
/**
 * BIP-322 tagged hash: SHA256(SHA256(tag) || SHA256(tag) || msg)
 * where tag = "BIP0322-signed-message"
 *
 * Per BIP-322 spec, message bytes are passed directly — no varint length prefix.
 * Ref: https://github.com/aibtcdev/x402-sponsor-relay/issues/135
 */
export declare function bip322TaggedHash(message: string): Uint8Array;
/**
 * Build the BIP-322 to_spend virtual transaction and return its txid (32 bytes, LE).
 *
 * The to_spend tx is a virtual legacy transaction:
 * - Input: txid=zero32, vout=0xFFFFFFFF, sequence=0, scriptSig = OP_0 push32 <msgHash>
 * - Output: amount=0, script=scriptPubKey of the signing address
 *
 * The txid is computed as doubleSha256 of the legacy (non-segwit) serialization.
 * The returned txid is already in the byte order used by transaction inputs (reversed).
 */
export declare function bip322BuildToSpendTxId(message: string, scriptPubKey: Uint8Array): Uint8Array;
/**
 * BIP-322 "simple" signing.
 *
 * Builds and signs the to_sign virtual transaction. The private key is used directly —
 * @scure/btc-signer's Transaction.signIdx() auto-detects the address type from witnessUtxo.script
 * and computes the correct sighash (BIP143 for P2WPKH, BIP341 for P2TR).
 *
 * @param message - Plain text message to sign
 * @param privateKey - 32-byte private key (P2WPKH key for bc1q, Taproot key for bc1p)
 * @param scriptPubKey - scriptPubKey of the signing address
 * @param tapInternalKey - For P2TR: the UNTWEAKED x-only pubkey (32 bytes). Required for Taproot
 *   signing. Must be the internal key BEFORE TapTweak, NOT the tweaked key in the scriptPubKey.
 * @returns Base64-encoded BIP-322 "simple" signature (serialized witness)
 */
export declare function bip322Sign(message: string, privateKey: Uint8Array, scriptPubKey: Uint8Array, tapInternalKey?: Uint8Array): string;
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