/**
 * MerkleTree class: builds a binary Merkle tree using tagged hashing (BIP-0340).
 * It can compute the Merkle root and generate proofs for given leaves.
 */
export declare class MerkleTree {
    private leafHashes;
    private levels;
    root: Buffer;
    private tagHashLeaf;
    private tagHashBranch;
    /**
     * Initialize the Merkle tree with an array of data (strings) and hashing tags.
     * @param leavesData - Array of strings representing leaf data.
     * @param leafTag - Tag for hashing leaves (context-specific tag). Defaults to "Bitcoin_Transaction".
     * @param branchTag - Tag for hashing internal nodes. Defaults to the same as leafTag.
     */
    constructor(leavesData: string[], leafTag?: string, branchTag?: string);
    /** Compute SHA256 hash of the tag (as UTF-8), used for tagged hashing. */
    private computeTagHash;
    /**
     * Compute a tagged hash: SHA256( tagHash || tagHash || message ).
     * @param tagHash - Buffer of 32-byte hash of the tag.
     * @param msg - Message bytes to hash.
     * @returns 32-byte SHA256 digest.
     */
    private taggedHash;
    /** Build the Merkle tree levels and root from the leaf hashes. */
    private buildTree;
    /**
     * Get the Merkle root as a hex string.
     * @returns Hexadecimal string of the Merkle root.
     */
    getHexRoot(): string;
    /**
     * Generate the Merkle proof for the leaf at the given index.
     * @param index - Index of the target leaf in the original input array.
     * @returns An array of proof elements, each a tuple [siblingHash (Buffer), side (0 or 1)].
     *          side = 0 indicates the sibling is the left node, side = 1 indicates the sibling is the right node.
     */
    getProof(index: number): {
        siblingHash: Buffer;
        side: 0 | 1;
    }[];
}