public override PaddingResult Pad(int nlen, BitString message)
{
// 1. Message Hashing
var hashedMessage = Sha.HashMessage(message).Digest;
// 2. Hash Encapsulation
var trailer = GetTrailer();
// Header is always 4, trailer is always 16
var paddingLen = nlen - Header.BitLength - Sha.HashFunction.OutputLen - trailer.BitLength;
var padding = GetPadding(paddingLen);
// ERROR: Split the padding into two chunks and put the hashed message in the middle
var firstChunkPadding = padding.GetMostSignificantBits(paddingLen - 8);
var secondChunkPadding = padding.GetLeastSignificantBits(8);
var IR = Header.GetDeepCopy();
IR = BitString.ConcatenateBits(IR, firstChunkPadding);
IR = BitString.ConcatenateBits(IR, hashedMessage);
IR = BitString.ConcatenateBits(IR, secondChunkPadding);
IR = BitString.ConcatenateBits(IR, trailer);
if (IR.BitLength != nlen)
{
return(new PaddingResult("Improper length for IR"));
}
return(new PaddingResult(IR));
}
public override PaddingResult Pad(int nlen, BitString message)
{
// 1. Message Hashing
var hashedMessage = Sha.HashMessage(message).Digest;
// 2. Hash Encapsulation
var trailer = new BitString("66CC"); // ERROR: The first byte of the trailer is unexpected
// Header is always 4, trailer is always 16
var paddingLen = nlen - Header.BitLength - Sha.HashFunction.OutputLen - trailer.BitLength;
var padding = GetPadding(paddingLen);
var IR = Header.GetDeepCopy();
IR = BitString.ConcatenateBits(IR, padding);
IR = BitString.ConcatenateBits(IR, hashedMessage);
IR = BitString.ConcatenateBits(IR, trailer); // ERROR: Change the trailer to something else
if (IR.BitLength != nlen)
{
return(new PaddingResult("Improper length for IR"));
}
return(new PaddingResult(IR));
}
public override PaddingResult Pad(int nlen, BitString message)
{
var emBits = nlen - 1;
var mHash = Sha.HashMessage(message).Digest;
var emLen = emBits.CeilingDivide(8);
// All byte values
if (emLen < mHash.BitLength / 8 + SaltLength + 2)
{
return(new PaddingResult("Encoding error"));
}
var salt = EntropyProvider.GetEntropy(SaltLength * 8);
var mPrime = BitString.Zeroes(64);
mPrime = BitString.ConcatenateBits(mPrime, mHash);
mPrime = BitString.ConcatenateBits(mPrime, salt);
var H = Sha.HashMessage(mPrime).Digest;
// All bit values
var PS = BitString.Zeroes(emLen * 8 - SaltLength * 8 - H.BitLength - 2 * 8);
var DB = PS.GetDeepCopy();
DB = BitString.ConcatenateBits(DB, ZeroOne);
DB = BitString.ConcatenateBits(DB, salt);
// All bit values
var dbMask = Mask.Mask(H, (emLen * 8) - H.BitLength - (1 * 8));
var maskedDB = BitString.XOR(DB, dbMask);
// Set leftmost bits to 0
for (var i = 0; i < 8 * emLen - emBits; i++)
{
maskedDB.Set(maskedDB.BitLength - i - 1, false);
}
// ERROR: split maskedDB into two chunks and insert hashed message in the middle
var firstChunkMask = maskedDB.GetMostSignificantBits(maskedDB.BitLength - 8);
var secondChunkMask = maskedDB.GetLeastSignificantBits(8);
var EM = firstChunkMask.GetDeepCopy();
EM = BitString.ConcatenateBits(EM, H);
EM = BitString.ConcatenateBits(EM, secondChunkMask);
EM = BitString.ConcatenateBits(EM, Bc);
return(new PaddingResult(EM));
}
public override PaddingResult Pad(int nlen, BitString message)
{
var emBits = nlen - 1;
var mHash = Sha.HashMessage(message).Digest;
var emLen = emBits.CeilingDivide(8);
// All byte values
if (emLen < mHash.BitLength / 8 + SaltLength + 2)
{
return(new PaddingResult("Encoding error"));
}
var salt = EntropyProvider.GetEntropy(SaltLength * 8);
var mPrime = BitString.Zeroes(64);
mPrime = BitString.ConcatenateBits(mPrime, mHash);
mPrime = BitString.ConcatenateBits(mPrime, salt);
var H = Sha.HashMessage(mPrime).Digest;
// All bit values
var PS = BitString.Zeroes(emLen * 8 - SaltLength * 8 - H.BitLength - 2 * 8);
var DB = PS.GetDeepCopy();
DB = BitString.ConcatenateBits(DB, ZeroOne);
DB = BitString.ConcatenateBits(DB, salt);
// All bit values
var dbMask = Mask.Mask(H, (emLen * 8) - H.BitLength - (1 * 8));
var maskedDB = BitString.XOR(DB, dbMask);
// Set leftmost bits to 0
for (var i = 0; i < 8 * emLen - emBits; i++)
{
maskedDB.Set(maskedDB.BitLength - i - 1, false);
}
var EM = maskedDB.GetDeepCopy();
EM = BitString.ConcatenateBits(EM, H);
EM = BitString.ConcatenateBits(EM, new BitString("4C")); // ERROR: should be 'BC'
return(new PaddingResult(EM));
}
public override PaddingResult Pad(int nlen, BitString message)
{
if (message.BitLength < GetHashAlgId().BitLength + 11 * 8)
{
return(new PaddingResult("Message length too short"));
}
var H = Sha.HashMessage(message).Digest;
var T = BitString.ConcatenateBits(GetHashAlgId(), H);
var psLen = nlen - (GetHashAlgId().BitLength + Sha.HashFunction.OutputLen) - 24;
var PS = BitString.Ones(psLen);
var EM = new BitString("00");
EM = BitString.ConcatenateBits(EM, new BitString("01"));
EM = BitString.ConcatenateBits(EM, PS);
EM = BitString.ConcatenateBits(EM, new BitString("44")); // ERROR: Should be 00
EM = BitString.ConcatenateBits(EM, T);
return(new PaddingResult(EM));
}