/**
 * Calculates the MD5 hash of a string.
 * Uses `CryptoJS` for MD5 calculation.  Throws an error if MD5 support is omitted in the build.
 *
 * @see https://cryptojs.gitbook.io/docs/
 *
 * @param value The string to hash.
 *
 * @returns A Promise that resolves with the MD5 hash as a hex string.
 *
 * @throws {Error} If SFC is built without MD5 support (SFC_OMIT_MD5 environment variable is set).
 */
export declare const md5: (value: string) => Promise<string>;
/**
 * Calculates the SHA256 hash of a string.
 *
 * @param value The input string.
 *
 * @returns A Promise that resolves with the SHA256 hash as a hexadecimal string.
 */
export declare const sha256: (value: string) => Promise<string>;
/**
 * Calculates the HMAC (Hash-based Message Authentication Code) of a string.
 *
 * @param value The input string (message).
 * @param secret The secret key.
 * @param algorithm The hashing algorithm to use (e.g., 'SHA-256'). Defaults to 'SHA-256'.
 *
 * @returns A Promise that resolves with the HMAC as a hexadecimal string.
 */
export declare const hmac: (value: string, secret: string, algorithm?: string) => Promise<string>;
/**
 * Encodes a string to Base64. Works in both Node.js and browser environments.
 *
 * @param string The string to encode.
 *
 * @returns The Base64 encoded string.
 */
export declare const encodeBase64: (string: string) => string;
/**
 * Decodes a Base64 encoded string. Works in both Node.js and browser environments.
 *
 * @param string The Base64 encoded string.
 *
 * @returns The decoded string.
 */
export declare const decodeBase64: (string: string) => string;
/**
 * Verifies an order success token by comparing its signature with an expected signature.
 *
 * @template T The type of the parsed payload.
 *
 * @param token The token to verify.
 * @param secret The secret key used to generate the signature.
 *
 * @returns A Promise resolving to the parsed token payload if the signature is valid, or undefined otherwise.
 */
export declare const verifyOrderSuccessToken: <T = unknown>(token: string, secret: string) => Promise<T | undefined>;
/**
 * Builds a hash payload by stringifying and Base64 encoding a given payload.
 *
 * @param payload The payload to hash.
 *
 * @returns The Base64 encoded hash payload.
 */
export declare const buildHashPayload: (payload: unknown) => string;
/**
 * Builds a signature for a given payload hash and secret.
 *
 * @param payloadHash The hash of the payload.
 * @param secret The secret key.
 *
 * @returns A Promise resolving to the Base64 encoded signature.
 */
export declare const buildSignature: (payloadHash: string, secret: string) => Promise<string>;