encrypt.cr

require "openssl"
require "openssl/cipher"
require "openssl/hmac"

struct Slice
  def self.from_hex(data : String)
    buffer = Slice(UInt8).new(data.bytesize / 2)
    i = 0
    data.each_char.each_slice(2) do |(high, low)|
      high = from_hex high
      low = from_hex low
      byte = (high << 4) + low
      buffer[i] = byte
      i += 1
    end
    buffer
  end

  private def self.from_hex(char)
    byte = char.ord
    byte -= 32 if byte >= 97 # upcase
    byte -= 7 if byte >= 65  # remove non-hex gap
    byte -= 48
    raise ArgumentError.new("invalid hex #{char}") unless 0 <= byte <= 16
    byte.to_u8
  end
end

IV = "00000000000000000000000000000000"
# IV = UInt8.slice(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
CLIENT_ID = "34700515"
MAC_KEY   = "C86984730E13686A0F069AE8CA71D8DA"
# MAC_KEY = UInt8.slice(200, 105, 132, 115, 14, 19, 104, 106, 15, 6, 154, 232, 202, 113, 216, 218)
ENCRYPTION_KEY = "911E1B7118F559896A5CB11048871781"

# ENCRYPTION_KEY = UInt8.slice(145, 30, 27, 113, 24, 245, 89, 137, 106, 92, 177, 16, 72, 135, 23, 129)

def generate_token
  request_time = "20160201182241"
  timezone = "03"
  reference_no = "123"
  phone_number = "905065707769"
  data = CLIENT_ID + timezone + request_time.to_s + length(phone_number) + phone_number + length(reference_no.to_s) + reference_no.to_s
  if data.size < 64
    padding_length = 64 - data.size
    data += '8'
    padding_length = 64 - data.size
    padding_length.times { data += '0' }
  end
  data
end

def encrypt(data)
  data = Slice.from_hex data
  encryption_key = Slice.from_hex ENCRYPTION_KEY
  iv = Slice.from_hex IV
  cipher = OpenSSL::Cipher.new("aes-128-cbc")
  cipher.encrypt
  cipher.key = encryption_key
  cipher.iv = iv
  encrypted_data = cipher.update data
  upcased = encrypted_data.hexstring.upcase
  hmac = OpenSSL::HMAC.hexdigest(:sha1, MAC_KEY, upcased)
  (upcased + hmac).upcase
end

def length(no)
  if no.size < 10
    '0' + no.size.to_s
  else
    no.size.to_s
  end
end