deliver.rb

require 'http'
require 'openssl'

document = File.read('create-hello-world.json')
date = Time.now.utc.httpdate

sha256 = OpenSSL::Digest::SHA256.new
digest = sha256.digest(document)
ed = 'SHA-256='+Base64.encode64(digest).strip

keypair = OpenSSL::PKey::RSA.new(File.read('private.pem'))
signed_string = "(request-target): post /inbox\nhost: mstd.seungjin.net\ndate: #{date}\ndigest: #{ed}"
signature= Base64.strict_encode64(keypair.sign(OpenSSL::Digest::SHA256.new, signed_string))
header = 'keyId="https://ap.dev.seungjin.net/actor#main-key",algorithm="rsa-sha256",headers="(request-target) host date digest",signature="' + signature + '"'

print HTTP.headers({ 'Host': 'mstd.seungjin.net',
	             'Date': date,
                     'Accept': 'application/activity+json',
                     'Digest': ed,
                     'Signature': header })
	.post('https://mstd.seungjin.net/inbox', body: document)