Encrypted before it leaves MT5.

Kalibre Bridge encrypts your MetaTrader 5 data on your computer before sending it. Our relay server stores only encrypted packets and cannot decrypt them. This page lists the methods we use and their limits.

Summary

• Kalibre Bridge is read-only. It cannot place, modify or close orders.
• Every packet is encrypted with AES-256-CTR and signed with HMAC-SHA256.
• The keys are derived from your pairing code. The code is never sent to our servers.
• The relay server deletes each packet within 2 hours.
• Kalibre never asks for your MT5 password.
• The license check sends your license key and MT5 account number to our license server.

Pairing code

The pairing code is a 32-byte secret generated by your browser's cryptographic random number generator. It starts with KLB1. It is stored in two places: this browser's local storage and the add-on's inputs in MT5.

Three keys are derived from the code with HMAC-SHA256: a channel ID used to find packets, an encryption key and a signing key. The server sees only the channel ID. The code and the other two keys cannot be derived from it.

Encryption and signatures

• Content is encrypted with AES-256 in CTR mode. Each packet uses a new nonce.
• Each packet is signed with HMAC-SHA256. The signature covers the channel ID, the packet's slot and the encrypted content.
• Your browser verifies the signature before decrypting. It rejects any packet that was changed, moved to another slot or signed with another code.
• Symbol names are encrypted. Packet names do not reveal which symbols you follow.

The protocol is implemented three times: in the MT5 add-on, in the lab and in an independent reference implementation. Automated tests check that all three produce identical packets from the same input.

Relay server

The server checks each packet's format and keeps it in short-lived storage. A newer packet of the same type replaces the old one, and every packet is deleted within 2 hours. Packet contents are not written to logs. Writes per channel are rate-limited.

Data Kalibre Bridge reads

Kalibre Bridge reads the following from MT5, encrypts it and sends it. You can turn off positions, quotes and trade history in the add-on's inputs.

• Closed candles for your symbols: time, open, high, low, close and tick volume. With the Symbols input empty, the first 12 symbols in Market Watch are used.
• Market Watch quotes for up to 40 symbols: bid, ask, time and description.
• Open positions: symbol, side, lot, open time and price, current price, stop, target, profit and magic number.
• Closed trades from the last 90 days (adjustable): symbol, side, lot, open and close time and price, profit, swap, commission, fees, magic number and comment.
• Deposits, withdrawals and other balance operations in the same period, with amount and time.
• Account currency, balance and equity.
• Broker name, server name and account type (demo, live or contest).

Kalibre Bridge does not read your MT5 password or personal details. The encrypted data does not include your account number.

License check

Kalibre Bridge and Kalibre Engine check your license with our license server. The request contains your license key, your MT5 account number, the product name and the add-on's language. We store the MT5 account numbers linked to each license, up to 2 per license. This request is separate from the encrypted data channel.

Alpaca and Tradier

API keys and tokens for Alpaca and Tradier are stored in this browser and sent only to Alpaca or Tradier. They are never sent to Kalibre servers. Kalibre makes read-only requests with them.

Limits

• Anyone with your pairing code can read your data. Do not share the code. To replace it, generate a new code in the lab and paste it into the add-on. The add-on then stops using the old code.
• Device security is your responsibility. Anyone with access to your computer or browser can see decrypted data.
• Traffic metadata is visible. The server sees packet size and timing for each channel.

To report a security issue, email markets@kalibrefin.com.