Add the Crypto Service to your modules.list:

-- modules.list
module wvds_crypto_service
module libcrypto.so.3
module libssl.so.3

Start the daemon in your Ned-Script:

local L4 = require("L4")
 
-- Create shared memory for communication
local crypto_ds = L4.Env.ram:create(64 * 1024, L4.Dataspace.ALL):m("rw")
 
-- Start Crypto Daemon
local crypto_daemon = L4.default_loader:start(
    { caps = { crypto_ep = crypto_ds:svr() } },
    "rom/wvds_crypto_service"
)
 
-- Your Gateway gets the client side
local gateway = L4.default_loader:start(
    { caps = { crypto_ep = crypto_ds } },
    "rom/iss_gateway"
)

Explanation:

• crypto_ds - Shared Memory Dataspace (64 KB)
• crypto_ep = crypto_ds:svr() - Server side for daemon
• crypto_ep = crypto_ds - Client side for your Gateway

Include the header and use the helper functions:

#include "wvds_crypto.h"
 
void encrypt_sensor_data(const uint8_t* data, size_t len) {
    uint8_t request[1024];
    size_t request_len = sizeof(request);
 
    // Build request
    int rc = wvds_build_aes_encrypt_request(
        request, &request_len,
        1,                      // Key-ID
        "sensor", 6,            // AAD
        data, len               // Plaintext
    );
 
    if (rc == 0) {
        // Copy request to shared memory
        memcpy(shared_memory, request, request_len);
 
        // Signal daemon
        signal_crypto_daemon();
 
        // Wait for response
        wait_for_response();
 
        // Parse response
        uint8_t nonce[12], tag[16], ciphertext[1024];
        size_t ct_len;
        wvds_parse_aes_encrypt_response(
            shared_memory, response_len,
            nonce, tag, ciphertext, &ct_len
        );
    }
}

That's all!

If you want to change the default settings, you can provide a config.json:

{
    "version": "0.2.0",
    "key_storage": {
        "type": "file",
        "path": "/data/keys",
        "encryption": "aes-256-gcm"
    },
    "rate_limit": {
        "max_requests_per_second": 1000,
        "burst": 100
    },
    "logging": {
        "level": "info",
        "destination": "syslog"
    }
}

Check if the daemon is running correctly:

# L4Re Console
l4> ps
... wvds_crypto_service ...
 
# Send test request
l4> crypto_test encrypt "Hello World"
OK: Ciphertext = 0x...

See also Security > Troubleshooting for additional errors.

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