presidio-hardened-crypto-channel

Secure cryptographic channel demonstrating ECDH key exchange, AES-256-GCM authenticated encryption, and HMAC integrity. Used in Experiment 1 of PRES-EDU-SEC-101 — Computer Security.

Setup

git clone https://github.com/presidio-v/presidio-hardened-crypto-channel.git
cd presidio-hardened-crypto-channel

Recommended: create a local virtual environment and install dependencies with the included helper:

python bootstrap.py

Activation is optional. Run commands through the virtual environment interpreter directly if shell policy prevents activation:

# macOS or Linux
.venv/bin/python main.py --demo keyexchange --parties Alice Bob

# Windows PowerShell
.\.venv\Scripts\python.exe main.py --demo keyexchange --parties Alice Bob

For the experiments below, use the virtual environment interpreter in place of python when the environment is not activated.

Experiments

Run 1 — ECDH Key Exchange

python main.py --demo keyexchange --parties Alice Bob

Both parties derive identical session keys without transmitting the secret.

Run 2 — AES-256-GCM Encryption

python main.py --demo symmetric --message "Hello from Alice" --key-size 256

Run 3 — Full Secure Channel

python main.py --demo channel --client Alice --server Bob --messages 10

Run 4 — Break It: Remove HMAC

python main.py --demo channel --no-hmac --tamper

Without authentication, a tampered message is detected by the GCM tag — demonstrating that AES-GCM provides both confidentiality and integrity.

Run 5 — Measure

python main.py --demo channel --messages 100 --duration 60
python report.py --experiment 1

What to Observe

• --no-hmac --tamper: AES-GCM's auth tag catches the flip — InvalidTag raised
• --tamper (HMAC on): HMAC check fires first, before decryption attempt
• Key takeaway: encryption provides confidentiality; GCM tag / HMAC provides integrity

Package Structure

src/presidio_crypto_channel/
├── keyexchange.py   X25519 ECDH + HKDF
├── symmetric.py     AES-256-GCM
├── channel.py       Full channel with optional HMAC
└── security.py      Logging + pip-audit

License

MIT

---

SDLC

This repository is developed under the Presidio hardened-family SDLC: https://github.com/presidio-v/presidio-hardened-docs/blob/main/sdlc/sdlc-report.md.