Use a developer secret

Prerequisites

Docker 17.05 or higher on the daemon and client.
Nodejs 14.0.0 or higher.
iExec SDK 7.2.0 or higher.
Familiarity with the basic concepts of Intel® SGX and SCONE framework.

Please make sure you have already checked the Quickstart, Your first application and Build trusted applications tutorials before learning how to use a developer secret.

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 associate an application developer secret to the runtime of an application.

The app developer secret is only exposed to your app inside authorized enclaves and never leaves them.

Your secrets are securely transferred with the SDK from your machine to the SMS over a TLS channel. Internally, your secrets are encrypted with standard AES encryption before being written to disk. Next releases will feature an SMS running entirely inside a trusted enclave.

Let's see how to do all of that!

Prepare your application

We will use the API countapi.xyz. This service keeps a count of hits on any couple of namespace/key (ex: https://api.countapi.xyz/hit/foo/bar). In this example, we will use an app developer secret to set namespace/key.

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

cd ~/iexec-projects
mkdir tee-developer-secret-app && cd tee-developer-secret-app
iexec init --skip-wallet
mkdir src
touch Dockerfile
touch sconify.sh

The application uses the developer secret to make a call to a secret endpoint of countapi.xyz and writes the result in a file:

Copy the following content in src/ .

src/app.js

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

(async () => {
  try {
    const iexecOut = process.env.IEXEC_OUT;
    // get the secret endpoint from app developer secret
    const secret = process.env.IEXEC_APP_DEVELOPER_SECRET;
    if (!secret) {
      console.log("missing IEXEC_APP_DEVELOPER_SECRET");
      process.exit(1);
    }
    // get the hit count from countapi
    const hitCount = await axios
      .get(`https://api.countapi.xyz/hit/iexec/${secret}`)
      .then(({ data }) => data.value);

    const result = `endpoint hit ${hitCount} times`;
    console.log(result);
    // write the result
    await fsPromises.writeFile(`${iexecOut}/result.txt`, result);
    // 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("something went wrong");
    process.exit(1);
  }
})();

src/app.py

import os
import json
import requests

try:
    iexec_out = os.environ["IEXEC_OUT"]

    # get the secret endpoint from app developer secret
    try:
        secret = os.environ["IEXEC_APP_DEVELOPER_SECRET"]
    except Exception:
        print("missing IEXEC_APP_DEVELOPER_SECRET")
        exit(1)

    # get the hit count from countapi
    response = requests.request("GET", "https://api.countapi.xyz/hit/iexec/" + secret)
    json_response = response.json()
    hit_count = json_response["value"]

    result = "endpoint hit " + str(hit_count) + " times"
    print(result)

    # write the result
    with open(iexec_out + "/result.txt", "w+") as fout:
        fout.write(result)

    # declare everything is computed
    with open(iexec_out + "/computed.json", "w+") as f:
        json.dump({ "deterministic-output-path" : iexec_out + "/result.txt" }, f)

except Exception:
    # do not log anything that could reveal the app developer secret!
    print("something went wrong")
    exit(1)

Build the TEE docker image

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

Dockerfile

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

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

COPY ./src /app

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

Dockerfile

FROM python:3.7.3-alpine3.10

RUN pip3 install requests

COPY ./src /app

ENTRYPOINT ["python3", "/app/app.py"]

sconify.sh

#!/bin/bash

# declare the app entrypoint
ENTRYPOINT="node /app/app.js"
# declare an image name
IMG_NAME=tee-developer-secret-app

IMG_FROM=${IMG_NAME}:temp-non-tee
IMG_TO=${IMG_NAME}:tee-debug

# build the regular non-TEE image
docker build . -t ${IMG_FROM}

# pull the SCONE curated image corresponding to our base image
docker pull registry.scontain.com/sconecuratedimages/node:14.4.0-alpine3.11

# run the sconifier to build the TEE image based on the non-TEE image
docker run -it --rm \
            -v /var/run/docker.sock:/var/run/docker.sock \
            registry.scontain.com/scone-production/iexec-sconify-image:5.3.15-v12 \
            sconify_iexec \
            --name=${IMG_NAME} \
            --from=${IMG_FROM} \
            --to=${IMG_TO} \
            --binary-fs \
            --fs-dir=/app \
            --host-path=/etc/hosts \
            --host-path=/etc/resolv.conf \
            --binary=/usr/local/bin/node \
            --heap=1G \
            --dlopen=2 \
            --no-color \
            --verbose \
            --command=${ENTRYPOINT} \
            && echo -e "\n------------------\n" \
            && echo "successfully built TEE docker image => ${IMG_TO}" \
            && echo "application mrenclave.fingerprint is $(docker run -it --rm -e SCONE_HASH=1 ${IMG_TO})"

sconify.sh

#!/bin/bash

# declare the app entrypoint
ENTRYPOINT="python3 /app/app.py"
# declare an image name
IMG_NAME=tee-developer-secret-app

IMG_FROM=${IMG_NAME}:temp-non-tee
IMG_TO=${IMG_NAME}:tee-debug

# build the regular non-TEE image
docker build . -t ${IMG_FROM}

# run the sconifier to build the TEE image based on the non-TEE image
docker run -it \
            -v /var/run/docker.sock:/var/run/docker.sock \
            registry.scontain.com/scone-production/iexec-sconify-image:5.3.15-v12 \
            sconify_iexec \
            --name=${IMG_NAME} \
            --from=${IMG_FROM} \
            --to=${IMG_TO} \
            --binary-fs \
            --fs-dir=/app \
            --host-path=/etc/hosts \
            --host-path=/etc/resolv.conf \
            --binary=/usr/local/bin/python3.7 \
            --heap=1G \
            --dlopen=2 \
            --no-color \
            --verbose \
            --command=${ENTRYPOINT} \
            && echo -e "\n------------------\n" \
            && echo "successfully built TEE docker image => ${IMG_TO}" \
            && echo "application mrenclave.fingerprint is $(docker run -it --rm -e SCONE_HASH=1 ${IMG_TO})"

Run the sconify.sh script to build the TEE-debug app.

The sconify.sh script prints the generated docker image name, you must retag this image and push it on dockerhub.

Test your app on iExec

At this stage, your application is ready to be tested on iExec. The process is similar to testing any type of application on the platform, with these minor exceptions:

Deploy the TEE app on iExec

TEE applications require some additional information to be filled in during deployment.

# prepare the TEE application template
iexec app init --tee

Edit iexec.json and fill in the standard keys and the mrenclave object:

{
  ...
  "app": {
    "owner": "0xF048eF3d7E3B33A465E0599E641BB29421f7Df92", // your address
    "name": "tee-developer-secret-app", // application name
    "type": "DOCKER",
    "multiaddr": "docker.io/username/tee-developer-secret-app:1.0.0", // app image
    "checksum": "0xf997788fcb5c9a47d8fa2653098da3c58343d400a82ca13d014d711d60560cac", // image digest
    "mrenclave": {
      "provider": "SCONE", // TEE provider (keep default value)
      "version": "v5", // Scone version (keep default value)
      "entrypoint": "node /app/app.js" OR "python3 /app/app.py", // your app image entrypoint
      "heapSize": 1073741824, // heap size in bytes (1GB)
      "fingerprint": "7d264f09de532fb1d55d25c4eb345a26454f4c21a1379e3813570538124a158e" // fingerprint of the enclave code (mrenclave), see how to retrieve it below
    }
  },
  ...
}

Run your TEE image with SCONE_HASH=1 to get the enclave fingerprint (mrenclave):

docker run -it --rm -e SCONE_HASH=1 tee-developer-secret-app:tee-debug

Deploy the app with the standard command:

iexec app deploy --chain bellecour

You will get a hexadecimal address for your deployed app. Use that address to push the app developer secret to the SMS.

For simplicity, we will use the secret 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 dataset encryption key to this SMS (this is fine for debugging but do not use to store production secrets).

These sed commands will do the trick:

# set a custom bellecour SMS in chain.json
sed -i 's|"bellecour": {},|"bellecour": { "sms": "https://v7.sms.debug-tee-services.bellecour.iex.ec" },|g' chain.json

# push the app developer secret to the SMS
iexec app push-secret --chain bellecour
# check the secret is available on the SMS
iexec app check-secret --chain bellecour

# restore the default configuration in chain.json
sed -i 's|"bellecour": { "sms": "https://v7.sms.debug-tee-services.bellecour.iex.ec" },|"bellecour": {},|g' chain.json

Run the TEE app

Specify the tag --tag tee in iexec app run command to run a tee app with an app developer secret.

One last thing, in order to run a TEE-debug app you will also need to select a debug workerpool, use the debug workerpool v7-debug.main.pools.iexec.eth.

You are now ready to run the app

iexec app run <appAddress> --tag tee --workerpool v7-debug.main.pools.iexec.eth --watch --chain bellecour

Next step?

Thanks to the explained confidential computing workflow, it is possible to use an app developer secret with a trusted application.

PreviousBuild trusted applications NextUse requester secrets

Last updated 9 months ago