/**
 * Compute an MD5 hash of the given data (RFC 1321).
 */
export declare function md5(data: Uint8Array): Uint8Array;
/**
 * Compute HMAC-MD5(key, data) per RFC 2104.
 */
export declare function hmacMD5(key: Uint8Array, data: Uint8Array): Uint8Array;
/**
 * Compute the CRAM-MD5 response string for SMTP authentication.
 *
 * @param challenge - base64-encoded challenge from server
 * @param user - SMTP username
 * @param pass - SMTP password
 * @returns base64-encoded CRAM-MD5 response
 */
export declare function computeCRAMMD5(challenge: string, user: string, pass: string): Promise<string>;