/**
 * Returns a string to be signed.
 *
 * @param date Current date in the format 'YYYYMMDDThhmmssZ'.
 * @param credentialScope String representing the credential scope with format 'YYYYMMDD/region/service/aws4_request'.
 * @param hashedRequest Hashed canonical request.
 *
 * @returns A string created by by concatenating the following strings, separated by newline characters:
 * - Algorithm
 * - RequestDateTime
 * - CredentialScope
 * - HashedCanonicalRequest
 *
 * @internal
 */
export declare const getStringToSign: (date: string, credentialScope: string, hashedRequest: string) => string;