test/test_shamir.rb

   1 require 'test/unit'
   2 require 'lib/secretsharing/shamir'
   3
   4 DEFAULT_SECRET_BITLENGTH = 256
   5
   6 class TestShamir < Test::Unit::TestCase
   7         def test_instantiation
   8                 assert_raise( ArgumentError ) { SecretSharing::Shamir.new }
   9                 s1 = SecretSharing::Shamir.new(5)
  10                 assert_equal(5, s1.n)
  11                 assert_equal(5, s1.k)
  12                 assert(! s1.secret_set?)
  13                 s2 = SecretSharing::Shamir.new(5, 3)
  14                 assert_equal(5, s2.n)
  15                 assert_equal(3, s2.k)
  16                 assert(! s2.secret_set?)
  17                 assert_raise( ArgumentError ) { SecretSharing::Shamir.new(5, 7) }
  18                 assert_raise( ArgumentError ) { SecretSharing::Shamir.new(1) }
  19         end
  20
  21         def test_create_random_secret
  22                 s = SecretSharing::Shamir.new(5)
  23                 s.create_random_secret()
  24                 assert(s.secret_set?)
  25                 assert_not_nil(s.secret)
  26                 assert_not_nil(s.shares)
  27                 assert_equal(Array, s.shares.class)
  28                 assert_equal(5, s.shares.length)
  29                 assert_equal(SecretSharing::Shamir::Share, s.shares[0].class)
  30                 assert_equal(DEFAULT_SECRET_BITLENGTH, s.secret_bitlength)
  31
  32                 # can only be called once
  33                 assert_raise( RuntimeError) { s.create_random_secret() }
  34
  35                 s2 = SecretSharing::Shamir.new(7)
  36                 s2.create_random_secret(512)
  37                 assert_equal(512, s2.secret_bitlength)
  38         end
  39
  40         def test_recover_secret_k_eq_n
  41                 s = SecretSharing::Shamir.new(5)
  42                 s.create_random_secret()
  43
  44                 s2 = SecretSharing::Shamir.new(5)
  45                 s2 << s.shares[0]
  46                 assert(! s2.secret_set?)
  47                 assert_nil(s2.secret)
  48                 # adding the same share raises an error
  49                 assert_raise( RuntimeError ) { s2 << s.shares[0] }
  50                 # add more shares
  51                 s2 << s.shares[1]
  52                 assert(! s2.secret_set?)
  53                 s2 << s.shares[2]
  54                 assert(! s2.secret_set?)
  55                 s2 << s.shares[3]
  56                 assert(! s2.secret_set?)
  57                 s2 << s.shares[4]
  58                 assert(s2.secret_set?)
  59                 assert_equal(s.secret, s2.secret)
  60         end
  61
  62         def test_recover_secret_k_le_n
  63                 s = SecretSharing::Shamir.new(5, 3)
  64                 s.create_random_secret()
  65
  66                 s2 = SecretSharing::Shamir.new(5, 3)
  67                 s2 << s.shares[0]
  68                 assert(! s2.secret_set?)
  69                 assert_nil(s2.secret)
  70                 # add more shares
  71                 s2 << s.shares[1]
  72                 assert(! s2.secret_set?)
  73                 s2 << s.shares[2]
  74                 assert(s2.secret_set?)
  75                 assert_equal(s.secret, s2.secret)
  76
  77                 # adding more shares than needed raises an error
  78                 assert_raise( RuntimeError ) { s2 << s.shares[3] }
  79         end
  80
  81         def test_recover_secret_k_le_n_strings
  82                 s = SecretSharing::Shamir.new(5, 3)
  83                 s.create_random_secret()
  84
  85                 s2 = SecretSharing::Shamir.new(5, 3)
  86                 s2 << "#{s.shares[0]}"
  87                 assert(! s2.secret_set?)
  88                 assert_nil(s2.secret)
  89                 # add more shares
  90                 s2 << "#{s.shares[1]}"
  91                 assert(! s2.secret_set?)
  92                 s2 << s.shares[2].to_s
  93                 assert(s2.secret_set?)
  94                 assert_equal(s.secret, s2.secret)
  95
  96                 # adding more shares than needed raises an error
  97                 assert_raise( RuntimeError ) { s2 << s.shares[3] }
  98         end
  99 end