@logismika/crypto/build/esm/kuznechik/decrypt.js

Crypto algorithms library

var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
    function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
    return new (P || (P = Promise))(function (resolve, reject) {
        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
        function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
        step((generator = generator.apply(thisArg, _arguments || [])).next());
    });
};
import { GOST_Kuz_X, BLOCK_SIZE, reverse_Pi, GOST_Kuz_GF_mul, l_vec, toByte } from "./common";
import { expandKey } from "./expandKey";
export const decrypt = (key, inStream, length) => __awaiter(void 0, void 0, void 0, function* () {
    if (inStream.length < length) {
        throw new Error("inStream's length shoud be greater or equal to length.");
    }
    if (inStream.length % BLOCK_SIZE != 0) {
        throw new Error(`inStream's length shoud devides on ${BLOCK_SIZE}.`);
    }
    const result = new Uint8Array(length);
    const expandedKey = yield expandKey(key);
    for (let i = 0; i < inStream.length; i += BLOCK_SIZE) {
        const delta = length - i;
        const block = inStream.subarray(i, i + BLOCK_SIZE);
        const decrypted = decryptBlock(expandedKey, block);
        const len = delta < BLOCK_SIZE ? delta : BLOCK_SIZE;
        result.set(decrypted.slice(0, len), i);
    }
    return result;
});
export const decryptBlock = (key, blk) => {
    let out_blk = blk.slice();
    out_blk = GOST_Kuz_X(out_blk, key.iter_key[9]);
    for (let i = 8; i >= 0; i -= 1) {
        out_blk = GOST_Kuz_reverse_L(out_blk);
        out_blk = GOST_Kuz_reverse_S(out_blk);
        out_blk = GOST_Kuz_X(key.iter_key[i], out_blk);
    }
    return out_blk;
};
const GOST_Kuz_reverse_S = (in_data) => {
    const out_data = new Uint8Array(BLOCK_SIZE);
    for (let i = 0; i < out_data.length; i += 1) {
        out_data[i] = reverse_Pi[in_data[i]];
    }
    return out_data;
};
const GOST_Kuz_reverse_L = (in_data) => {
    let result = in_data.slice();
    for (let i = 0; i < 16; i += 1) {
        result = GOST_Kuz_reverse_R(result);
    }
    return result;
};
const GOST_Kuz_reverse_R = (state) => {
    let a_0 = state[15];
    const internal = new Uint8Array(BLOCK_SIZE);
    ;
    for (let i = 1; i < internal.length; i++) {
        internal[i] = state[i - 1];
        a_0 ^= GOST_Kuz_GF_mul(toByte(internal[i]), toByte(l_vec[i]));
    }
    internal[0] = a_0;
    return internal;
};
export const decrypt_testPackage = { GOST_Kuz_reverse_S, GOST_Kuz_reverse_L, GOST_Kuz_reverse_R };