So all the other containers are in the Docker Swarm and we want to expose a real HTTP/S interface to clients outside of the Swarm, that makes sense. Clients have to get an API key first.

API key

Let's produce a 256-bits key that we'll convert in an hex string to store and use with openssl hmac feature.

dd if=/dev/urandom bs=32 count=1 2> /dev/null | xxd -pc 32

The key is stored in keys.properties and must be given to the client. This is a secret key. keys.properties looks like this:

#keyid=hex(key)
key001=2df1eeea370eacdc5cf7e96c2d82140d1568079a5d4d87006ec8718a98883b36
key002=50c5e483b80964595508f214229b014aa6c013594d57d38bcb841093a39f1d83

Bearer token

Following JWT (JSON Web Tokens) standard, we build a bearer token that will be in the request header and signed with the secret key. We need this in the request header:

Authorization: Bearer <token>

...where token is:

token = hhh.ppp.sss

...where hhh is the header in base64, ppp is the payload in base64 and sss is the signature. Here are the expected formats and contents:

header = {"alg":"HS256","typ":"JWT"}
header64 = base64(header) = eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9Cg==

payload = {"id":"001","exp":1538528077}
payload64 = base64(payload) = eyJpZCI6IjAwMSIsImV4cCI6MTUzODUyODA3N30K

The "id" property is the client id and the "exp" property should be current epoch time + 10 seconds, like:

$((`date +"%s"`+10))

...so that the request will be expired in 10 seconds. That should take care of most Replay attacks if any. You should run nginx with TLS so that the replay attack can't be possible.

signature = hmacsha256(header64.payload64, key)

token = header64 + "." + payload64 + "." + signature

cURL example of an API invocation

Instruction should be in the form:

curl -v -H "Authorization: Bearer hhh.ppp.sss" localhost

10 seconds request expiration:

id="001";h64=$(echo "{\"alg\":\"HS256\",\"typ\":\"JWT\"}" | base64);p64=$(echo "{\"id\":\"$id\",\"exp\":$((`date +"%s"`+10))}" | base64);k="2df1eeea370eacdc5cf7e96c2d82140d1568079a5d4d87006ec8718a98883b36";s=$(echo "$h64.$p64" | openssl dgst -hmac "$k" -sha256 -r | cut -sd ' ' -f1);token="$h64.$p64.$s";curl -v -H "Authorization: Bearer $token" https://localhost/getbestblockhash

60 seconds request expiration:

id="001";h64=$(echo "{\"alg\":\"HS256\",\"typ\":\"JWT\"}" | base64);p64=$(echo "{\"id\":\"$id\",\"exp\":$((`date +"%s"`+60))}" | base64);k="2df1eeea370eacdc5cf7e96c2d82140d1568079a5d4d87006ec8718a98883b36";s=$(echo "$h64.$p64" | openssl dgst -hmac "$k" -sha256 -r | cut -sd ' ' -f1);token="$h64.$p64.$s";curl -v -H "Authorization: Bearer $token" https://localhost/getbestblockhash

SSL

Create your key and certificates.

openssl req -subj '/CN=localhost' -x509 -newkey rsa:4096 -nodes -keyout ~/cyphernode/private/key.pem -out ~/cyphernode/certs/cert.pem -days 365

Use default-ssl.conf as the template instead of default.conf.

Build

Create your API key and put it in keys.properties

dd if=/dev/urandom bs=32 count=1 2> /dev/null | xxd -pc 32

Build and run docker image

docker build -t authapi .
docker run -d --rm --name authapi -p 80:80 -p 443:443 --network cyphernodenet -v "~/cyphernode/certs:/etc/ssl/certs" -v "~/cyphernode/private:/etc/ssl/private" authapi

Invoke cyphernode through authenticated API

id="001";h64=$(echo "{\"alg\":\"HS256\",\"typ\":\"JWT\"}" | base64);p64=$(echo "{\"id\":\"$id\",\"exp\":$((`date +"%s"`+10))}" | base64);k="2df1eeea370eacdc5cf7e96c2d82140d1568079a5d4d87006ec8718a98883b36";s=$(echo "$h64.$p64" | openssl dgst -hmac "$k" -sha256 -r | cut -sd ' ' -f1);token="$h64.$p64.$s";curl -v -H "Authorization: Bearer $token" https://localhost/getbestblockhash

Technicalities

h64=$(echo "{\"alg\":\"HS256\",\"typ\":\"JWT\"}" | base64)
p64=$(echo "{\"id\":\"001\",\"exp\":$((`date +"%s"`+10))}" | base64)
k="2df1eeea370eacdc5cf7e96c2d82140d1568079a5d4d87006ec8718a98883b36"
s=$(echo "$h64.$p64" | openssl dgst -hmac "$k" -sha256 -r | cut -sd ' ' -f1)
token="$h64.$p64.$s"