Access requester secrets

In this tutorial, you will learn how to:

leverage requester secrets by using the following environment variables in your code: IEXEC_REQUESTER_SECRET_1, IEXEC_REQUESTER_SECRET_2, ..., IEXEC_REQUESTER_SECRET_<N>
map your personal secrets to those environment variables when buying an execution on iExec network

Before going any further, make sure you managed to Build your first application with Scone framework.

Prerequisites:

Docker 17.05 or higher on the daemon and client.
iExec SDK 8.0.0 or higher. Install the iExec SDK
Familiarity with the basic concepts of Intel® SGX and SCONE framework.

Trusted Execution Environments offer a huge advantage from a security perspective. They guarantee that the behavior of execution does not change even when launched on an untrusted remote machine. The data inside this type of environment is also protected, which allows its monetization while preventing leakage.

With iExec, it is possible to securely consume requester-provided secrets in the application.

The requester secrets are only exposed to authorized apps inside enclaves and never leave them.

Your secrets are transferred with the SDK from your machine to the SMS over a TLS channel.

Let's see how to do all of that!

Prepare your application

For demo purposes, we omitted some development best practices in these examples.

Make sure to check your field's best practices before going to production.

Let's develop an application designed to evaluate the function: $f(x) = ax^3 + bx^2 + cx + d$

where the coefficients a, b, c and d are kept confidential using an application secret, and the input x is kept confidential using the requester's secret.

Let's create a directory tree for this app in ~/iexec-projects/.

cd ~/iexec-projects
mkdir tee-requester-secrets-app && cd tee-requester-secrets-app
iexec init --skip-wallet
mkdir src
touch Dockerfile
touch sconify.sh
chmod +x sconify.sh

Make sure your chain.json content is correct.

The application uses the requester's secret to evaluate a secret function f(x), keeping the input x also confidential, and writes the result in a file.

Copy the following content in src/ .

src/app.js

const fsPromises = require("fs").promises;

(async () => {
  try {
    const iexecOut = process.env.IEXEC_OUT;
    // get the secret endpoint from app developer secret
    const app_secret = process.env.IEXEC_APP_DEVELOPER_SECRET;
    let a = 1, b = 1, c = 1, d = 1; // Default values
    const req_secret = process.env.IEXEC_REQUESTER_SECRET_1;
    let x = 1 

    if (!app_secret) {
      console.log("missing IEXEC_APP_DEVELOPER_SECRET");
    } else {
      // Split the secret into coefficients
      let coefficients = app_secret.split(";");
      if (coefficients.length !== 4) {
        console.log("problem with the length of IEXEC_APP_DEVELOPER_SECRET");
      } else {
        [a, b, c, d] = coefficients.map(parseFloat);
      }
    }

    if (!req_secret) {
      console.log("missing IEXEC_REQUESTER_SECRET_1");
    } else {
      x = parseFloat(req_secret); 
    }

    // Function to compute f(x)
    function cubicPolynomial(x) {
      return a * Math.pow(x, 3) + b * Math.pow(x, 2) + c * x + d;
    }

    // Compute f(x)
    let result = cubicPolynomial(x);
    // Create result object
    const resultObj = {
      "x": x,
      "result": result
    };
    
    // Convert result object to JSON string
    const resultJson = JSON.stringify(resultObj);
    // Write result to file
    await fsPromises.writeFile(`${iexecOut}/result.txt`, resultJson);

    // Declare everything is computed
    const computedJsonObj = {
      "deterministic-output-path": `${iexecOut}/result.txt`,
    };
    await fsPromises.writeFile(
      `${iexecOut}/computed.json`,
      JSON.stringify(computedJsonObj)
    );
  } catch (e) {
    // do not log anything that could reveal the app developer secret!
    console.log(e);
    process.exit(1);
  }
})();

src/app.py

import os
import json

# Retrieve the output directory path
iexec_out = os.environ.get("IEXEC_OUT")
print(iexec_out)

# Get the app secret containing coefficients
app_secret = os.environ.get("IEXEC_APP_DEVELOPER_SECRET")
a, b, c, d = 1, 1, 1, 1  # Default values
if not app_secret:
    print("Warning: Missing IEXEC_APP_DEVELOPER_SECRET. Using default coefficients.")
else:
    coefficients = app_secret.split(";")
    if len(coefficients) != 4:
        print("Warning: Problem with the length of IEXEC_APP_DEVELOPER_SECRET")
    else:
        a, b, c, d = map(float, coefficients)

# Get the input value from the requester secret
req_secret = os.environ.get("IEXEC_REQUESTER_SECRET_1")
x = 1  # Default value
if not req_secret:
    print("Warning: Missing IEXEC_REQUESTER_SECRET_1. Using default input value.")
else:
    try:
        x = float(req_secret)
    except ValueError as e:
        print("Invalid value for IEXEC_REQUESTER_SECRET_1:", e)
        exit(1)

# Function to compute f(x)
def cubic_polynomial(x):
    return a * x**3 + b * x**2 + c * x + d

# Compute f(x)
result = cubic_polynomial(x)
print("compute")

# Create result object
result_obj = {
    "x": x,
    "result": result
}

# Convert result object to JSON string
result_json = json.dumps(result_obj)

# Write result to file
with open(f"{iexec_out}/result.txt", "w+") as f:
    f.write(result_json)

# Declare computation complete
computed_json_obj = {
    "deterministic-output-path": f"{iexec_out}/result.txt",
}
with open(f"{iexec_out}/computed.json", "w+") as f:
    json.dump(computed_json_obj, f)

Build a Confidential Computing application

Create the Dockerfile

In this section, you will:

Build the native image of the application as described in Build your first application.
Create and execute the sconify.sh script to build the Scone TEE application as we saw in Build Scone app > Prepare your application.

The Dockerfile and the build scripts are similar to the ones we saw previously for a trusted application:

Create the Dockerfile

For a Javascript application:

# Starting from a base image supported by SCONE
FROM node:14-alpine3.11

# install your dependencies
RUN mkdir /app && cd /app

COPY ./src /app

ENTRYPOINT [ "node", "/app/app.js"]

For a Python application:

FROM python:3.7.3-alpine3.10

### install python dependencies if you have some
COPY ./src /app
ENTRYPOINT ["python3", "/app/app.py"]

Build the docker image.

docker build . --tag <docker-hub-user>/secret-function:1.0.0

Follow the steps described in Build Scone app > Build the TEE docker image.

Update the sconify.sh script with the variables as follow:

# Declare image related variables
IMG_NAME=tee-scone-secret-function
IMG_FROM=<docker-hub-user>/secret-function:1.0.0
IMG_TO=<docker-hub-user>/${IMG_NAME}:1.0.0-debug

Run the sconify.sh script to build the Scone TEE application:

./sconify.sh

Push the image on Docker Hub

docker push <docker-hub-user>/tee-scone-secret-function:1.0.0-debug

Test your app on iExec

At this stage, your application is ready to be tested on iExec with the following steps:

Deploy the TEE app on iExec

Deploy your application

For simplicity, we will use secrets in a TEE-debug app on a debug workerpool. The debug workerpool is connected to a debug Secret Management Service so we will send the requester secrets to this SMS (this is fine for debugging but do not use to store production secrets).

In this example, the app developer's secret must be strictly defined in the following format a;b;c;d. For example set your secret to 1;1;1;1 for coeficients a,b,c,d. For details, go to Use app secret

iexec app  push-secret <appAddress>
iexec app  check-secret <appAddress>

Push some requester secrets to the SMS

iexec requester push-secret x1 --secret-value 1

Check secrets availability in the SMS

iexec requester check-secret x1

Run the TEE app

You are now ready to run the app with requester secrets.

Specify the --secret and --tag tee,scone options in iexec app run command to run a tee app with requester secrets on Scone

iexec app run <appAddress> \
  --tag tee,scone \
  --workerpool debug-v8-bellecour.main.pools.iexec.eth \
  --secret 1=x1 \
  --watch

The option --secret <secretMapping...> allows the requester to provision any number of secrets with the mapping syntax <key>=<name>.

example:

--secret 1=foo 3=bar

the secret named foo will be available in IEXEC_REQUESTER_SECRET_1
the secret named bar will be available in IEXEC_REQUESTER_SECRET_3
IEXEC_REQUESTER_SECRET_2 will be skipped

Next step?

Thanks to the explained confidential computing workflow, you now know how to consume requester secrets in a Confidential Computing application.

To go further, check out how to:

PreviousAttach a secret to your app NextAccess a confidential dataset

Last updated 2 months ago