Add tests for AES decryption.

Co-authored-by: Robert Haines <rhaines@manchester.ac.uk>

Author: jplot

test/crypto/aes_encryption_test.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class AESDecrypterTest < MiniTest::Test
+  def setup
+    @decrypter256 = ::Zip::AESDecrypter.new('password', ::Zip::AESEncryption::STRENGTH_256_BIT)
+    @decrypter128 = ::Zip::AESDecrypter.new('password', ::Zip::AESEncryption::STRENGTH_128_BIT)
+  end
+
+  def test_header_bytesize
+    assert_equal 18, @decrypter256.header_bytesize
+  end
+
+  def test_gp_flags
+    assert_equal 1, @decrypter256.gp_flags
+  end
+
+  def test_decrypt_aes256
+    @decrypter256.reset!([125, 138, 163, 42, 19, 1, 155, 66, 203, 174, 183, 235, 197, 122, 232, 68, 252, 225].pack('C*'))
+    assert_equal 'a', @decrypter256.decrypt([161].map(&:chr).join)
+  end
+
+  def test_decrypt_aes128
+    @decrypter128.reset!([127, 254, 117, 113, 255, 209, 171, 131, 179, 106].pack('C*'))
+    assert_equal [75, 4, 0], @decrypter128.decrypt([34, 33, 106].map(&:chr).join).chars.map(&:ord)
+  end
+
+  def test_reset!
+    @decrypter256.reset!([125, 138, 163, 42, 19, 1, 155, 66, 203, 174, 183, 235, 197, 122, 232, 68, 252, 225].pack('C*'))
+    assert_equal 'a', @decrypter256.decrypt([161].map(&:chr).join)
+
+    @decrypter256.reset!([118, 221, 166, 27, 165, 141, 24, 122, 227, 197, 52, 135, 222, 67, 221, 92, 231, 117].pack('C*'))
+    assert_equal 'b', @decrypter256.decrypt([135].map(&:chr).join)
+  end
+end

test/data/zip-aes-128.txt

@@ -0,0 +1 @@
+a

test/data/zip-aes-128.zip

@@ -0,0 +1 @@
+b

test/data/zip-aes-256.txt

@@ -4,8 +4,12 @@
 
 class EncryptionTest < MiniTest::Test
   ENCRYPT_ZIP_TEST_FILE = 'test/data/zipWithEncryption.zip'
+  AES_128_ZIP_TEST_FILE = 'test/data/zip-aes-128.zip'
+  AES_256_ZIP_TEST_FILE = 'test/data/zip-aes-256.zip'
   INPUT_FILE1 = 'test/data/file1.txt'
   INPUT_FILE2 = 'test/data/file2.txt'
+  INPUT_FILE3 = 'test/data/zip-aes-128.txt'
+  INPUT_FILE4 = 'test/data/zip-aes-256.txt'
 
   def setup
     Zip.default_compression = ::Zlib::DEFAULT_COMPRESSION
@@ -65,4 +69,32 @@ def test_decrypt
       assert_equal ::File.read(INPUT_FILE2), zis.read
     end
   end
+
+  def test_aes_128_decrypt
+    Zip::InputStream.open(
+      AES_128_ZIP_TEST_FILE,
+      decrypter: Zip::AESDecrypter.new('password', Zip::AESEncryption::STRENGTH_128_BIT)
+    ) do |zis|
+      entry = zis.get_next_entry
+      assert_equal 'a', entry.name
+      assert_equal 1, entry.size
+      assert_equal ::File.read(INPUT_FILE3), zis.read
+    end
+  end
+
+  def test_aes_256_decrypt
+    Zip::InputStream.open(
+      AES_256_ZIP_TEST_FILE,
+      decrypter: Zip::AESDecrypter.new('password', Zip::AESEncryption::STRENGTH_256_BIT)
+    ) do |zis|
+      entry = zis.get_next_entry
+      assert_equal 'a', entry.name
+      assert_equal 0, entry.size
+      assert_equal '', zis.read
+      entry = zis.get_next_entry
+      assert_equal 'b', entry.name
+      assert_equal 1, entry.size
+      assert_equal ::File.read(INPUT_FILE4), zis.read
+    end
+  end
 end