module Dse

# File lib/dse.rb, line 15
def self.decrypt(data, password, cipher_type = DEFAULT_CIPHER)
  decoded_data = Base64.strict_decode64(data.to_s)
  self.decrypt_data(decoded_data, password, cipher_type)
end

# File lib/dse.rb, line 9
def self.encrypt(data, password, cipher_type = DEFAULT_CIPHER)
  hashed_password = OpenSSL::Digest::SHA256.digest(password)
  encrypted_data = encrypt_data(data.to_s, hashed_password, cipher_type)
  Base64.strict_encode64(encrypted_data)
end

# File lib/dse.rb, line 32
def self.decrypt_data(data, password, cipher_type)
  cipher = OpenSSL::Cipher.new(cipher_type)
  cipher.decrypt
  cipher.key = OpenSSL::Digest::SHA256.digest(password)
  cipher.iv = iv = data.slice!(0,16)
  cipher.update(data) + cipher.final
end

# File lib/dse.rb, line 22
def self.encrypt_data(data, password, cipher_type)
  cipher = OpenSSL::Cipher.new(cipher_type)
  cipher.encrypt
  cipher.key = password
  cipher.iv = iv = cipher.random_iv

  # final result: 16 byte IV + cipher block + final block
  iv + cipher.update(data) + cipher.final
end