import BigNumber from './BigNumber.js';
import Signature from './Signature.js';
import Point from './Point.js';
/**
 * Generates a digital signature for a given message.
 *
 * @function sign
 * @param msg - The BigNumber message for which the signature has to be computed.
 * @param key - Private key in BigNumber.
 * @param forceLowS - Optional boolean flag if True forces "s" to be the lower of two possible values.
 * @param customK - Optional specification for k value, which can be a function or BigNumber.
 * @returns Returns the elliptic curve digital signature of the message.
 *
 * @example
 * const msg = new BigNumber('2664878')
 * const key = new BigNumber('123456')
 * const signature = sign(msg, key)
 */
/**
 * SECURITY NOTE:
 *
 * This function implements ECDSA signing and expects `msg` to be the output of
 * a cryptographic hash function (e.g. SHA-256), not an arbitrary-length message.
 *
 * Per FIPS 186-4 / SEC 1, the message representative used by ECDSA must not
 * exceed the bit length of the curve order `n`. Inputs larger than `n` must be
 * hashed before signing.
 *
 * As a short-term mitigation for TOB-22, this implementation explicitly rejects
 * messages whose bit length exceeds that of the curve order.
 *
 * Long-term, callers SHOULD always hash messages before invoking `sign()`.
 */
export declare const sign: (msg: BigNumber, key: BigNumber, forceLowS?: boolean, customK?: BigNumber | ((iter: number) => BigNumber)) => Signature;
/**
 * Verifies a digital signature of a given message.
 *
 * Message and key used during the signature generation process, and the previously computed signature
 * are used to validate the authenticity of the digital signature.
 *
 * @function verify
 * @param msg - The BigNumber message for which the signature has to be verified.
 * @param sig - Signature object consisting of parameters 'r' and 's'.
 * @param key - Public key in Point.
 * @returns Returns true if the signature is valid and false otherwise.
 *
 * @example
 * const msg = new BigNumber('2664878', 16)
 * const key = new Point(new BigNumber(10), new BigNumber(20)
 * const signature = sign(msg, new BigNumber('123456'))
 * const isVerified = verify(msg, sig, key)
 */
/**
 * SECURITY NOTE:
 *
 * This verification routine assumes that `msg` is a hashed message
 * representative produced using the same hash function used during signing.
 *
 * As part of TOB-22 short-term hardening, messages exceeding the curve order
 * bit length are rejected to prevent misuse with non-hashed inputs.
 */
export declare const verify: (msg: BigNumber, sig: Signature, key: Point) => boolean;
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