/// <summary>
/// Call this method to format correctly for KMAC
/// </summary>
/// <param name="message">BitString representation of message</param>
/// <param name="capacity">Capacity</param>
/// <param name="customizationString">Character string for customization</param>
/// <returns>Formatted message before calling Keccak</returns>
public static BitString FormatMessage(BitString message, BitString key, int capacity, int macLength, bool xof)
{
var macLengthBitString = new BitString(new System.Numerics.BigInteger(macLength));
BitString newMessage;
if (capacity == 256)
{
newMessage = Sha3DerivedHelpers.Bytepad(Sha3DerivedHelpers.EncodeString(key), new BitString("A8")); // "A8" is 164 (the rate)
}
else // capacity == 512
{
newMessage = Sha3DerivedHelpers.Bytepad(Sha3DerivedHelpers.EncodeString(key), new BitString("88")); // "88" is 136 (the rate)
}
if (xof)
{
var concatenatedMessageEncode = Sha3DerivedHelpers.SafeConcatenation(message, Sha3DerivedHelpers.RightEncode(BitString.Zeroes(8)));
newMessage = BitString.ConcatenateBits(newMessage, concatenatedMessageEncode);
}
else
{
var concatenatedMessageEncode = Sha3DerivedHelpers.SafeConcatenation(message, Sha3DerivedHelpers.RightEncode(macLengthBitString));
newMessage = BitString.ConcatenateBits(newMessage, concatenatedMessageEncode);
}
return(newMessage);
}
public static BitString FormatMessage(BitString message, int capacity, string functionNameString, BitString customization)
{
var functionName = Sha3DerivedHelpers.StringToHex(functionNameString);
BitString bytepad;
if (capacity == 256)
{
bytepad = Sha3DerivedHelpers.Bytepad(BitString.ConcatenateBits(Sha3DerivedHelpers.EncodeString(functionName), Sha3DerivedHelpers.EncodeString(customization)), new BitString("A8")); // "A8" is 168 (the rate)
}
else // capacity == 512
{
bytepad = Sha3DerivedHelpers.Bytepad(BitString.ConcatenateBits(Sha3DerivedHelpers.EncodeString(functionName), Sha3DerivedHelpers.EncodeString(customization)), new BitString("88")); // "88" is 136 (the rate)
}
message = BitString.ConcatenateBits(bytepad, message);
message = Sha3DerivedHelpers.SafeConcatenation(message, BitString.Zeroes(2));
return(message);
}
/// <summary>
/// Call this method to format correctly for ParallelHash
/// </summary>
/// <param name="message">BitString representation of message</param>
/// <param name="cSHAKE">A cSHAKE module</param>
/// <param name="capacity">Capacity</param>
/// <param name="blockSize">The desired block size in bytes</param>
/// <param name="xof">Is it xof mode?</param>
/// <returns>Formatted message before calling Keccak</returns>
public static BitString FormatMessage(BitString message, CSHAKE.CSHAKE cSHAKE, int digestLength, int capacity, int blockSize, bool xof)
{
// 1. n = ⌈ (len(X)/8) / B ⌉.
var numberOfBlocks = ((message.BitLength / 8) + blockSize - 1) / blockSize;
// 2. z = left_encode(B).
var newMessage = Sha3DerivedHelpers.LeftEncode(Sha3DerivedHelpers.IntToBitString(blockSize));
// 3. for i = 0 to n−1:
// z = z || cSHAKE128(substring(X, i*B*8, (i+1)*B*8), 256, "", "").
var strings = new List <BitString>();
var hashFunction = new HashFunction {
DigestLength = capacity, Capacity = capacity
};
for (var i = 0; i < numberOfBlocks; i++)
{
var substring = Sha3DerivedHelpers.SubString(message, i * blockSize * 8, (i + 1) * blockSize * 8);
strings.Add(cSHAKE.HashMessage(hashFunction, substring, "").Digest);
}
for (int i = 0; i < numberOfBlocks; i++)
{
newMessage = BitString.ConcatenateBits(newMessage, strings[i]);
}
// 4. z = z || right_encode(n) || right_encode(L).
newMessage = BitString.ConcatenateBits(newMessage, Sha3DerivedHelpers.RightEncode(Sha3DerivedHelpers.IntToBitString(numberOfBlocks)));
if (xof)
{
newMessage = BitString.ConcatenateBits(newMessage, Sha3DerivedHelpers.RightEncode(BitString.Zeroes(8)));
}
else
{
newMessage = BitString.ConcatenateBits(newMessage, Sha3DerivedHelpers.RightEncode(Sha3DerivedHelpers.IntToBitString(digestLength)));
}
return(newMessage);
}
/// <summary>
/// Call this method to format correctly for TupleHash
/// </summary>
/// <param name="tuple">List of BitString representation of message</param>
/// <param name="digestLength">Desired output size</param>
/// <param name="xof">Is it xof mode?</param>
/// <returns>Formatted message before calling Keccak</returns>
public static BitString FormatMessage(IEnumerable <BitString> tuple, int digestLength, bool xof)
{
BitString message = new BitString(0);
foreach (BitString element in tuple)
{
var encodedPiece = Sha3DerivedHelpers.EncodeString(element);
message = Sha3DerivedHelpers.SafeConcatenation(message, encodedPiece);
}
if (xof)
{
var rightEncode = Sha3DerivedHelpers.RightEncode(BitString.Zeroes(8));
message = Sha3DerivedHelpers.SafeConcatenation(message, rightEncode);
}
else
{
var rightEncode = Sha3DerivedHelpers.RightEncode(Sha3DerivedHelpers.IntToBitString(digestLength));
message = Sha3DerivedHelpers.SafeConcatenation(message, rightEncode);
}
return(message);
}
/// <summary>
/// Call this method to format correctly for cSHAKE
/// </summary>
/// <param name="message">BitString representation of message</param>
/// <param name="capacity">Capacity</param>
/// <param name="functionNameString">Character string representation of functionName</param>
/// <param name="customizationString">Character string for customization</param>
/// <returns>Formatted message before calling Keccak</returns>
public static BitString FormatMessage(BitString message, int capacity, string functionNameString, string customizationString)
{
var customization = Sha3DerivedHelpers.StringToHex(customizationString);
return(FormatMessage(message, capacity, functionNameString, customization));
}
