@li0ard/kalyna/dist/modes/gcm.js

Kalyna (DSTU 7624:2014) cipher implementation in pure TypeScript

import { concatBytes, equalBytes, numberToBytesLE, xor } from "@li0ard/gost3413/dist/utils.js";
import { ctr } from "../index.js";
import { gf2mMul } from "../utils.js";
/**
 * Compute GMAC
 * @param cipherClass Initialized cipher class
 * @param authData Data to be authenticated
 * @param cipherData Ciphertext to be authenticated (Only for GMAC)
 * @param q MAC size
 */
export const gmac = (cipherClass, authData, cipherData = new Uint8Array(), q = 16) => {
    const blockSize = cipherClass.blockSize;
    const H = cipherClass.encrypt(new Uint8Array(blockSize));
    let B = new Uint8Array(blockSize);
    let i = 0;
    while (i < authData.length) {
        const blockSizeToProcess = Math.min(blockSize, authData.length - i);
        const block = new Uint8Array(blockSize);
        for (let j = 0; j < blockSizeToProcess; j++)
            block[j] = authData[i + j];
        if (blockSizeToProcess < blockSize)
            block[blockSizeToProcess] = 0x80;
        for (let j = 0; j < blockSize; j++)
            B[j] ^= block[j];
        B = gf2mMul(blockSize, B, H);
        i += blockSize;
    }
    i = 0;
    while (i < cipherData.length) {
        const blockSizeToProcess = Math.min(blockSize, cipherData.length - i);
        const block = new Uint8Array(blockSize);
        for (let j = 0; j < blockSizeToProcess; j++)
            block[j] = cipherData[i + j];
        if (blockSizeToProcess < blockSize)
            block[blockSizeToProcess] = 0x80;
        for (let j = 0; j < blockSize; j++)
            B[j] ^= block[j];
        B = gf2mMul(blockSize, B, H);
        i += blockSize;
    }
    B = xor(B, concatBytes(numberToBytesLE(authData.length * 8, blockSize / 2), numberToBytesLE(cipherData.length * 8, blockSize / 2)));
    // B = gf2mMul(blockSize, B, H);
    return cipherClass.encrypt(B).slice(0, q);
};
/**
 * Encrypts data using Galois/Counter Mode (GCM) mode
 * @param cipherClass Initialized cipher class
 * @param plainData Data to be encrypted and authenticated
 * @param iv Initialization vector
 * @param authData Additional data to be authenticated
 * @param q MAC size
 */
export const encryptGCM = (cipherClass, plainData, iv, authData = new Uint8Array(), q = 16) => {
    const enc = ctr(cipherClass, plainData, iv);
    return concatBytes(enc, gmac(cipherClass, authData, enc, q));
};
/**
 * Decrypts data using Galois/Counter Mode (GCM) mode
 * @param cipherClass Initialized cipher class
 * @param plainData Data to be decrypted and authenticated
 * @param iv Initialization vector
 * @param authData Additional data to be authenticated
 * @param q MAC size
 */
export const decryptGCM = (cipherClass, encryptedData, iv, authData = new Uint8Array(), q = 16) => {
    const enc = encryptedData.slice(0, -q);
    const hC = gmac(cipherClass, authData, enc, q);
    if (!equalBytes(encryptedData.slice(-q), hC))
        throw new Error("Invalid MAC");
    return ctr(cipherClass, enc, iv);
};