public Skein(int state_size, int output_size)
{
// Make sure the output bit size > 0
if (output_size <= 0)
throw new CryptographicException("Output bit size must be greater than zero.");
m_CipherStateBits = state_size;
m_CipherStateBytes = state_size / 8;
m_CipherStateWords = state_size / 64;
base.HashSizeValue = output_size;
m_OutputBytes = (output_size + 7) / 8;
// Figure out which cipher we need based on
// the state size
m_Cipher = ThreefishCipher.CreateCipher(state_size);
if (m_Cipher == null) throw new CryptographicException("Unsupported state size.");
// Allocate buffers
m_InputBuffer = new byte[m_CipherStateBytes];
m_CipherInput = new ulong[m_CipherStateWords];
m_State = new ulong[m_CipherStateWords];
// Allocate tweak
m_Tweak = new UBITweak();
// Set default payload type (regular straight hashing)
m_PayloadType = UBIType.Message;
// Generate the configuration string
m_Configuration = new SkeinConfig(this);
m_Configuration.SetSchema("SHA3");
m_Configuration.SetVersion(1);
m_Configuration.GenerateConfiguration();
// Initialize hash
Initialize();
}
public ThreefishTransform(
byte[] key, byte[] iv, ThreefishTransformType type, CipherMode mode, PaddingMode padding
)
{
m_TransformType = type;
m_CipherMode = mode;
m_PaddingMode = padding;
m_CipherBytes = key.Length;
m_CipherWords = key.Length / 8;
m_CipherBits = key.Length * 8;
// Allocate working blocks now so that we don't
// have to allocate them each time
// Transform(Final)Block is called
m_Block = new ulong[m_CipherWords];
m_TempBlock = new ulong[m_CipherWords];
m_StreamBytes = new byte[m_CipherBytes];
// Allocate IV and set value
m_IV = new ulong[m_CipherWords];
GetBytes(iv, 0, m_IV, m_CipherBytes);
// Figure out which cipher we need based on
// the cipher bit size
switch (m_CipherBits)
{
case 256:
m_Cipher = new Threefish256();
break;
case 512:
m_Cipher = new Threefish512();
break;
case 1024:
m_Cipher = new Threefish1024();
break;
default:
throw new CryptographicException("Unsupported key/block size.");
}
bool e = (type == ThreefishTransformType.Encrypt);
switch(m_CipherMode)
{
case CipherMode.ECB:
m_TransformFunc = e ? new TransformFunc(ECB_Encrypt) : new TransformFunc(ECB_Decrypt);
break;
case CipherMode.CBC:
m_TransformFunc = e ? new TransformFunc(CBC_Encrypt) : new TransformFunc(CBC_Decrypt);
break;
case CipherMode.OFB:
m_TransformFunc = new TransformFunc(OFB_ApplyStream);
break;
case CipherMode.CFB:
m_TransformFunc = e ? new TransformFunc(CFB_Encrypt) : new TransformFunc(CFB_Decrypt);
break;
case CipherMode.CTS:
throw new CryptographicException("CTS mode not supported.");
}
// Set the key
ulong[] key_words = new ulong[m_CipherWords];
GetBytes(key, 0, key_words, m_CipherBytes);
m_Cipher.SetKey(key_words);
InitializeBlocks();
}
