/**
 * Package gcm implements GCM mode for block ciphers.
 */
import type { AEAD } from "@stablelib/aead";
import type { BlockCipher } from "@stablelib/blockcipher";
export declare const NONCE_LENGTH = 12;
export declare const TAG_LENGTH = 16;
/**
 * Galois/Counter Mode AEAD
 *
 * Defined in NIST SP-800-38D.
 *
 * This implementation only supports 12-byte nonces and 16-byte tags:
 * these parameters are the most secure and most commonly used.
 */
export declare class GCM implements AEAD {
    readonly nonceLength = 12;
    readonly tagLength = 16;
    private _subkey;
    private _cipher;
    /**
     * Creates a new GCM instance with the given block cipher.
     *
     * Block size of cipher must be equal to 16.
     */
    constructor(cipher: BlockCipher);
    /**
     * Encrypts and authenticates plaintext, authenticates associated data,
     * and returns sealed ciphertext, which includes authentication tag.
     *
     * If dst is given (it must be the size of plaintext + the size of tag length)
     * the result will be put into it. Dst and plaintext must not overlap.
     */
    seal(nonce: Uint8Array, plaintext: Uint8Array, associatedData?: Uint8Array, dst?: Uint8Array): Uint8Array;
    /**
     * Authenticates sealed ciphertext (which includes authentication tag) and
     * associated data, decrypts ciphertext and returns decrypted plaintext.
     *
     * If authentication fails, it returns null.
     *
     * If dst is given (it must be of ciphertext length minus tag length),
     * the result will be put into it. Dst and plaintext must not overlap.
     */
    open(nonce: Uint8Array, sealed: Uint8Array, associatedData?: Uint8Array, dst?: Uint8Array): Uint8Array | null;
    clean(): this;
    private _authenticate;
}