🔒 Secure room name generation using secrets module

[Adityasingh-8858]

🎯 What

The /initiate-transfer endpoint was using random.choices to generate a 4-character suffix for briefing room names. This is cryptographically insecure and can lead to predictable identifiers.

⚠️ Risk

An attacker might be able to predict the briefing room names, potentially allowing unauthorized access or room name squatting if the randomness can be forecasted. While the suffix is only 4 characters, using a secure RNG is a best practice for any identifier generation.

🛡️ Solution

Replaced random.choices with secrets.choice from the Python secrets module, which is designed for generating cryptographically strong random numbers suitable for managing data such as passwords, account authentication, security tokens, and related secrets.

The implementation now uses:

import secrets, string
alphabet = string.ascii_lowercase + string.digits
suffix = ''.join(secrets.choice(alphabet) for _ in range(4))

This maintains the same character set and length while providing better security.

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PR created automatically by Jules for task 2496506577130441873 started by @Deepaksingh7238

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Pull request overview

This PR strengthens identifier generation in the FastAPI backend by switching the /initiate-transfer briefing-room suffix generation to a cryptographically secure RNG, reducing predictability of room names.

Changes:

• Replace random.choices(...) with secrets.choice(...) for the 4-character room-name suffix.
• Introduce a local alphabet variable to keep the character set explicit and unchanged (lowercase letters + digits).

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