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#!/usr/bin/env ruby
require 'openssl'
require 'securerandom'
require 'sinatra'
Users = {
"Athena" => "Passw0rd!"
}
Services = {
"Mail" => "{FvM<kgG}VpHxKJO;6Zo"
}
def ticket(username, service, password)
cipher = OpenSSL::Cipher::AES.new(256, :CBC).encrypt
cipher.key = Digest::SHA2.digest(password)
s = cipher.update("#{username}:#{service}") + cipher.final
s.unpack('H*')[0].upcase + ?\n
end
def noleak(msg, ul, sl)
puts "Error: #{msg}, returning nonsense to avoid leakage."
ticket(SecureRandom.alphanumeric(ul), SecureRandom.alphanumeric(sl), SecureRandom.alphanumeric(16))
end
post '/ticket' do
request.body.rewind
data = JSON.parse(request.body.read)
next "Invalid request\n" unless data.keys.sort == %w(password service username)
ul = data["username"].length
sl = data["service"].length
next noleak("Invalid service", ul, sl) unless Services.keys.include?(data["service"])
next noleak("Invalid username", ul, sl) unless Users.keys.include?(data["username"])
next noleak("Invalid password", ul, sl) unless Users[data["username"]] == data["password"]
next ticket(data["username"], data["service"], Services[data["service"]])
end
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