#!/bin/bash

# Generate a JWT, with signature verified using OpenSSL
#
# Prerequisites: openssl, jq
#
# Usage: source ./openssl_signing_console.sh
#
# For a more complete explanation, see ./openssl_signing_console.rst


# Generate a key and extract the public part
openssl ecparam -name secp256k1 -genkey -noout -out private.pem
openssl ec -in private.pem -pubout -out public.pem

# Use test data
header='{"alg":"ES256K", "issuer": "", "typ":"JWT"}'
payload='{"@context": "http://schema.org", "@type": "PlanAction", "identifier": "did:ethr:0xb86913f83A867b5Ef04902419614A6FF67466c12", "name": "Test", "description": "Me"}'

header_b64=$(echo -n "$header" | jq -c -M . | tr -d '\n' | base64 | tr -d '=' | tr '+' '-' | tr '/' '_')
payload_b64=$(echo -n "$payload" | jq -c -M . | tr -d '\n' | base64 | tr -d '=' | tr '+' '-' | tr '/' '_')

signing_input="$header_b64.$payload_b64"

signature=$(echo -n "$signing_input" | openssl dgst -sha256 -sign private.pem | openssl base64 -e)

echo -n "$signing_input" | openssl dgst -sha256 -verify public.pem -signature <(echo -n "$signature" | openssl base64 -d)





# Read binary signature and encode it to Base64 URL-Safe format
signature_b64=$(echo -n "$signature" | base64 | tr -d '=' | tr '+' '-' | tr '/' '_')

# Construct the JWT
jwt="$signing_input.$signature_b64"

echo Resulting JWT: $jwt