export declare const PKCS7_INVALID = "invalid ciphertext";
/**
 * Apply PKCS7 padding to `data` so the result length is a multiple of 16.
 * Padding length is always 1-16 bytes so a full pad block is appended when
 * `data.length` is already block-aligned.
 * @param data  Input bytes of any length
 * @returns     New Uint8Array padded to the next 16-byte boundary
 */
export declare function pkcs7Pad(data: Uint8Array): Uint8Array;
/**
 * Remove PKCS7 padding from a block-aligned buffer in constant time.
 *
 * Branch-free over all secret bits, padding length and per-byte comparisons
 * are accumulated into a single `bad` flag with no early exit. Closes the
 * Vaudenay 2002 padding-oracle surface. Throws a single generic
 * `RangeError('invalid ciphertext')` for every failure mode: empty input,
 * non-block-aligned length, padding byte out of range 1-16, and any per-byte
 * mismatch in the padding region.
 * @param data  Block-aligned ciphertext (length must be a multiple of 16)
 * @returns     Plaintext with padding removed
 */
export declare function pkcs7Strip(data: Uint8Array): Uint8Array;