/// <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);
}
