API Security with encrypted value in endpoints

# === MOCK AES KEY (32 bytes = AES-256) ===
AES_KEY = b"this_is_a_32_byte_secret_key!!"

def encrypt_aes(data: str) -> str:
    cipher = AES.new(AES_KEY, AES.MODE_GCM)
    ciphertext, tag = cipher.encrypt_and_digest(data.encode())

    encrypted_payload = {
        "nonce": base64.b64encode(cipher.nonce).decode(),
        "ciphertext": base64.b64encode(ciphertext).decode(),
        "tag": base64.b64encode(tag).decode()
    }

    return base64.b64encode(json.dumps(encrypted_payload).encode()).decode()

from fastapi import FastAPI
from Crypto.Cipher import AES
import base64
import json

app = FastAPI()

# === MOCK AES KEY (32 bytes = AES-256) ===
AES_KEY = b"this_is_a_32_byte_secret_key!!"

def encrypt_aes(data: str) -> str:
    cipher = AES.new(AES_KEY, AES.MODE_GCM)
    ciphertext, tag = cipher.encrypt_and_digest(data.encode())

    encrypted_payload = {
        "nonce": base64.b64encode(cipher.nonce).decode(),
        "ciphertext": base64.b64encode(ciphertext).decode(),
        "tag": base64.b64encode(tag).decode()
    }

    return base64.b64encode(json.dumps(encrypted_payload).encode()).decode()


# =========================
# Customer Endpoints
# =========================

@app.get("/customer/1")
def get_customer_1():
    return {
        "customer_id": 1,
        "full_name": "John Smith",
        "bank_name": "Mock National Bank",
        "account_type": "Savings",
        "account_number_encrypted": encrypt_aes("123-4-56789-0"),
        "balance_encrypted": encrypt_aes("125430.75"),
        "currency": "USD",
        "status": "Active",
        "encryption": "AES-256-GCM"
    }


@app.get("/customer/2")
def get_customer_2():
    return {
        "customer_id": 2,
        "full_name": "Emma Johnson",
        "bank_name": "Mock National Bank",
        "account_type": "Checking",
        "account_number_encrypted": encrypt_aes("987-6-54321-9"),
        "balance_encrypted": encrypt_aes("98750.25"),
        "currency": "USD",
        "status": "Active",
        "encryption": "AES-256-GCM"
    }


# =========================
# Branch Endpoint (NO Encryption)
# =========================

@app.get("/branch")
def get_branches():
    return {
        "bank_name": "Mock National Bank",
        "total_branches": 3,
        "branches": [
            {
                "branch_id": 1,
                "branch_name": "Bangkok Main Branch",
                "address": "123 Silom Road, Bangkok, Thailand",
                "phone": "+66-2-123-4567",
                "status": "Open"
            },
            {
                "branch_id": 2,
                "branch_name": "Chiang Mai Branch",
                "address": "88 Nimmanhaemin Road, Chiang Mai, Thailand",
                "phone": "+66-53-987-654",
                "status": "Open"
            },
            {
                "branch_id": 3,
                "branch_name": "Phuket Branch",
                "address": "55 Patong Beach Road, Phuket, Thailand",
                "phone": "+66-76-111-222",
                "status": "Closed"
            }
        ]
    }


# =========================
# Finance Endpoint (ALL Encrypted)
# =========================

@app.get("/finance")
def get_finance_summary():
    return {
        "bank_name": "Mock National Bank",
        "report_type": "Branch Deposit Summary",
        "currency": "USD",
        "encryption": "AES-256-GCM",
        "branches": [
            {
                "branch_id": 1,
                "branch_name": "Bangkok Main Branch",
                "total_deposit_encrypted": encrypt_aes("12500000.50")
            },
            {
                "branch_id": 2,
                "branch_name": "Chiang Mai Branch",
                "total_deposit_encrypted": encrypt_aes("5420000.75")
            },
            {
                "branch_id": 3,
                "branch_name": "Phuket Branch",
                "total_deposit_encrypted": encrypt_aes("3189000.00")
            }
        ]
    }