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//
// CFB Unit Tests
//
// Author:
// Sebastien Pouliot <sebastien@xamarin.com>
//
// Copyright (C) 2013 Xamarin Inc (http://www.xamarin.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using NUnit.Framework;
namespace MonoTests.System.Security.Cryptography {
public abstract class CfbTests {
protected abstract SymmetricAlgorithm GetInstance ();
protected void ProcessBlockSizes (SymmetricAlgorithm algo)
{
algo.Padding = PaddingMode.None;
foreach (KeySizes bs in algo.LegalBlockSizes) {
for (int blockSize = bs.MinSize; blockSize <= bs.MaxSize; blockSize += bs.SkipSize) {
algo.BlockSize = blockSize;
ProcessKeySizes (algo);
// SkipSize can be 0 (e.g. DES) if only one block size is available
if (blockSize == bs.MaxSize)
break;
}
}
}
protected void ProcessKeySizes (SymmetricAlgorithm algo)
{
foreach (KeySizes ks in algo.LegalKeySizes) {
for (int keySize = ks.MinSize; keySize <= ks.MaxSize; keySize += ks.SkipSize) {
algo.KeySize = keySize;
algo.Key = GetKey (algo);
algo.IV = new byte [algo.BlockSize / 8];
ProcessPadding (algo);
// SkipSize can be 0 (e.g. DES) if only one key size is available
if (keySize == ks.MaxSize)
break;
}
}
}
protected abstract PaddingMode[] PaddingModes { get; }
protected void ProcessPadding (SymmetricAlgorithm algo)
{
foreach (var padding in PaddingModes) {
algo.Padding = padding;
CFB (algo);
}
}
protected virtual byte [] GetKey (SymmetricAlgorithm algo)
{
return new byte [algo.KeySize / 8];
}
protected abstract void CFB (SymmetricAlgorithm algo);
protected int GetId (SymmetricAlgorithm algo)
{
return (algo.BlockSize << 24) + (algo.KeySize << 16) + ((int) algo.Padding << 8) + algo.FeedbackSize;
}
protected virtual string GetExpectedResult (SymmetricAlgorithm algo, byte [] encryptedData)
{
int id = GetId (algo);
string expected = BitConverter.ToString (encryptedData);
Console.WriteLine ("// block size: {0}, key size: {1}, padding: {2}, feedback: {3}", algo.BlockSize, algo.KeySize, algo.Padding, algo.FeedbackSize);
Console.WriteLine ("{{ {0}, \"{1}\" }},", id, expected);
return expected;
}
protected void CFB (SymmetricAlgorithm algo, int feedbackSize)
{
byte [] data = new byte [feedbackSize >> 3];
for (int i = 0; i < data.Length; i++)
data [i] = (byte) (0xff - i);
byte [] encdata = Encryptor (algo, data);
string expected = GetExpectedResult (algo, encdata);
string actual = null;
if (algo.Padding == PaddingMode.ISO10126) {
// ISO10126 uses random data so we can't compare the last bytes with a test vector
actual = BitConverter.ToString (encdata, 0, data.Length);
expected = expected.Substring (0, actual.Length);
} else {
actual = BitConverter.ToString (encdata);
}
Assert.AreEqual (expected, actual, "encrypted value");
byte [] decdata = Decryptor (algo, encdata);
if (algo.Padding == PaddingMode.Zeros) {
// this requires manually unpadding the decrypted data - but unlike ISO10126
// we know the rest of the data will be 0 (not random) so we check that
byte [] resize = new byte [data.Length];
Array.Copy (decdata, 0, resize, 0, resize.Length);
// all zeros afterward!
for (int i = resize.Length; i < decdata.Length; i++)
Assert.AreEqual (0, decdata [i], "padding zero {0}", i);
decdata = resize;
}
Assert.AreEqual (data, decdata, "Roundtrip {0} {1}", algo.Mode, algo.FeedbackSize);
}
protected virtual int GetTransformBlockSize (SymmetricAlgorithm algo)
{
return algo.BlockSize / 8;
}
byte [] Encryptor (SymmetricAlgorithm algo, byte [] data)
{
using (ICryptoTransform t = algo.CreateEncryptor (algo.Key, algo.IV)) {
int size = GetTransformBlockSize (algo);
Assert.That (t.InputBlockSize == size, "Encryptor InputBlockSize {0} {1}", algo.Mode, algo.FeedbackSize);
Assert.That (t.OutputBlockSize == size, "Encryptor OutputBlockSize {0} {1}", algo.Mode, algo.FeedbackSize);
return t.TransformFinalBlock (data, 0, data.Length);
}
}
byte [] Decryptor (SymmetricAlgorithm algo, byte [] encdata)
{
using (ICryptoTransform t = algo.CreateDecryptor (algo.Key, algo.IV)) {
int size = GetTransformBlockSize (algo);
Assert.That (t.InputBlockSize == size, "Decryptor InputBlockSize {0} {1}", algo.Mode, algo.FeedbackSize);
Assert.That (t.OutputBlockSize == size, "Decryptor OutputBlockSize {0} {1}", algo.Mode, algo.FeedbackSize);
return t.TransformFinalBlock (encdata, 0, encdata.Length);
}
}
}
// most algorithms are "limited" and only support CFB8
public abstract class LimitedCfbTests : CfbTests {
// all *CryptoServiceProvider implementation refuse Padding.None
static PaddingMode[] csp_padding_modes = new [] { PaddingMode.PKCS7, PaddingMode.Zeros, PaddingMode.ANSIX923, PaddingMode.ISO10126 };
protected override PaddingMode [] PaddingModes {
get { return csp_padding_modes; }
}
[Test]
[ExpectedException (typeof (CryptographicException))]
public void Cfb_None ()
{
using (var algo = GetInstance ()) {
algo.Padding = PaddingMode.None;
CFB (algo, 8);
}
}
protected override void CFB (SymmetricAlgorithm algo)
{
algo.Mode = CipherMode.CFB;
// System.Security.Cryptography.CryptographicException : Feedback size for the cipher feedback mode (CFB) must be 8 bits.
algo.FeedbackSize = 8;
CFB (algo, algo.FeedbackSize);
}
}
// DES and 3DES won't accept a key with all zero (since it's a weak key for them)
public abstract class WeakKeyCfbTests : LimitedCfbTests {
protected override byte [] GetKey (SymmetricAlgorithm algo)
{
var key = base.GetKey (algo);
for (byte i = 0; i < key.Length; i++)
key [i] = i;
return key;
}
}
}
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