@tgsnake/core/lib/src/crypto/SecretChat.js

Pure Telegram MTProto library for nodejs

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.kdf = kdf;
exports.pack = pack;
exports.unpack = unpack;
const platform_node_js_1 = require("../platform.node.js");
const index_js_1 = require("../errors/index.js");
const index_js_2 = require("../raw/index.js");
const helpers_js_1 = require("../helpers.js");
const Aes_js_1 = require("./Aes.js");
const index_js_3 = require("../raw/index.js");
function sha256(data) {
    const hash = platform_node_js_1.crypto.createHash('sha256');
    hash.update(data);
    return hash.digest();
}
function sha1(data) {
    const hash = platform_node_js_1.crypto.createHash('sha1');
    hash.update(data);
    return hash.digest();
}
function kdf(sharedKey, msgKey, isAdmin, v1 = false) {
    const x = isAdmin ? 0 : 8;
    if (v1) {
        const sha1A = sha1(platform_node_js_1.Buffer.concat([
            msgKey,
            sharedKey.subarray(x, x + 32),
        ]));
        const sha1B = sha1(platform_node_js_1.Buffer.concat([
            sharedKey.subarray(x + 32, x + 48),
            msgKey,
            sharedKey.subarray(x + 48, x + 64),
        ]));
        const sha1C = sha1(platform_node_js_1.Buffer.concat([
            sharedKey.subarray(x + 64, x + 96),
            msgKey,
        ]));
        const sha1D = sha1(platform_node_js_1.Buffer.concat([
            msgKey,
            sharedKey.subarray(x + 96, x + 128),
        ]));
        const aesKey = platform_node_js_1.Buffer.concat([
            sha1A.subarray(0, 8),
            sha1B.subarray(8, 20),
            sha1C.subarray(4, 16),
        ]);
        const aesIv = platform_node_js_1.Buffer.concat([
            sha1A.subarray(8, 20),
            sha1B.subarray(0, 8),
            sha1C.subarray(16, 20),
            sha1D.subarray(0, 8),
        ]);
        return [aesKey, aesIv];
    }
    else {
        const sha256A = sha256(platform_node_js_1.Buffer.concat([
            msgKey,
            sharedKey.subarray(x, x + 36),
        ]));
        const sha256B = sha256(platform_node_js_1.Buffer.concat([
            sharedKey.subarray(x + 40, x + 76),
            msgKey,
        ]));
        const aesKey = platform_node_js_1.Buffer.concat([
            sha256A.subarray(0, 8),
            sha256B.subarray(8, 24),
            sha256A.subarray(24, 32),
        ]);
        const aesIv = platform_node_js_1.Buffer.concat([
            sha256B.subarray(0, 8),
            sha256A.subarray(8, 24),
            sha256B.subarray(24, 32),
        ]);
        return [aesKey, aesIv];
    }
}
function pack(message, sharedKey, inSeqNo, outSeqNo, isAdmin, layer, mtproto = 2) {
    let msg = message;
    if (layer > 8) {
        msg = new index_js_3.Raw.DecryptedMessageLayer17({
            randomBytes: platform_node_js_1.crypto.randomBytes(15 + 4 * Math.floor(Math.random() * 3)),
            layer: layer,
            inSeqNo: inSeqNo,
            outSeqNo: outSeqNo,
            message: message,
        });
    }
    const bytesmsg = msg.write();
    const length = platform_node_js_1.Buffer.alloc(4);
    length.writeUInt32LE(platform_node_js_1.Buffer.byteLength(bytesmsg), 0);
    const data = platform_node_js_1.Buffer.concat([length, bytesmsg]);
    const padding = platform_node_js_1.Buffer.from(platform_node_js_1.crypto.randomBytes((0, helpers_js_1.mod)(-(platform_node_js_1.Buffer.byteLength(data) + 16), 16) + 16));
    const paddedMsg = platform_node_js_1.Buffer.concat([
        data,
        padding,
    ]);
    const msgKeyLarge = sha256(platform_node_js_1.Buffer.concat([
        sharedKey.subarray(88 + (isAdmin ? 0 : 8), 88 + (isAdmin ? 0 : 8) + 32),
        paddedMsg,
    ]));
    const msgKey = mtproto === 1 ? sha1(data).subarray(-16) : msgKeyLarge.subarray(8, 8 + 16);
    const [aesKey, aesIv] = mtproto === 1 ? kdf(sharedKey, msgKey, isAdmin, true) : kdf(sharedKey, msgKey, isAdmin, false);
    const fingerprintKey = sha1(sharedKey).subarray(-8);
    return platform_node_js_1.Buffer.concat([
        fingerprintKey,
        msgKey,
        (0, Aes_js_1.ige256Encrypt)(paddedMsg, aesKey, aesIv),
    ]);
}
async function unpack(message, sharedKey, isAdmin, mtproto = 2) {
    const data = new index_js_2.BytesIO(message.bytes);
    const serverFingerprintKey = data.readBigInt64LE();
    const clientFingerprintKey = sha1(sharedKey).subarray(-8).readBigInt64LE();
    if (serverFingerprintKey !== clientFingerprintKey) {
        throw new index_js_1.SecretChatError.FingerprintMismatch();
    }
    const msgKey = data.read(16);
    const encryptedMsg = data.read();
    const [aesKey, aesIv] = mtproto === 1 ? kdf(sharedKey, msgKey, isAdmin, true) : kdf(sharedKey, msgKey, !isAdmin, false);
    const decryptedMsg = new index_js_2.BytesIO((0, Aes_js_1.ige256Decrypt)(encryptedMsg, aesKey, aesIv));
    const msgLength = decryptedMsg.readUInt32LE();
    const payload = decryptedMsg.read();
    const padding = payload.subarray(msgLength);
    const msgKeyLarge = sha256(platform_node_js_1.Buffer.concat([
        sharedKey.subarray(88 + (isAdmin ? 8 : 0), 88 + (isAdmin ? 8 : 0) + 32),
        decryptedMsg.buffer,
    ]));
    const clientMsgKey = mtproto === 1
        ? sha1(decryptedMsg.buffer.subarray(0, 4 + msgLength)).subarray(-16)
        : msgKeyLarge.subarray(8, 8 + 16);
    index_js_1.SecurityCheckMismatch.check(msgKey.equals(clientMsgKey), 'Given message key is not equal with client side');
    index_js_1.SecurityCheckMismatch.check(platform_node_js_1.Buffer.byteLength(padding) >= 12 && platform_node_js_1.Buffer.byteLength(padding) <= 1024, 'Payload padding is lower than 12 or bigger than 1024');
    index_js_1.SecurityCheckMismatch.check((0, helpers_js_1.mod)(platform_node_js_1.Buffer.byteLength(padding), 4) === 0, 'Mod of padding length with 4 is equal with zero');
    const msg = await index_js_2.TLObject.read(new index_js_2.BytesIO(payload));
    return msg;
}