private NotBitArray Coding_rounds(int round_count, NotBitArray block, NotBitArray[] Keys, bool is_encoding)
{
int start, finish, step;
if (is_encoding)
{
start = 1;
step = 1;
finish = round_count + 1;
}
else
{
start = round_count;
step = -1;
finish = 0;
}
block = Permutation(block, IP_table);
NotBitArray L_block = new NotBitArray(block.bits.Substring(0, Block_size / 2)),
R_block = new NotBitArray(block.bits.Substring(Block_size / 2));
for (int i = start; i != finish; i += step)
{
NotBitArray buffer = R_block;
R_block = L_block.Xor(F(R_block, Keys[i - 1]));
L_block = buffer;
}
return(Permutation(new NotBitArray(R_block.bits + L_block.bits), IP_1_table));
}
NotBitArray Permutation(NotBitArray Input_array, int[] table)
{
StringBuilder sb = new StringBuilder();
for (int i = 0; i < table.Length; i++)
{
sb.Append(Input_array.bits[table[i] - 1]);
}
return(new NotBitArray(sb.ToString()));
}
NotBitArray Get_CD_i(int round, NotBitArray CD)
{
int shift = round > 1 && // instead of shifts table;
(round + 1) % 9 != 0 && // '%' to have some 1-bit shift
(round + 1) % 16 != 0 ? 2 : 1; // on more then 16 rounds
return(new NotBitArray(new StringBuilder()
.Append(CD.bits.Substring(shift, 28 - shift))
.Append(CD.bits.Substring(0, shift))
.Append(CD.bits.Substring(28 + shift, 28 - shift))
.Append(CD.bits.Substring(28, shift)).ToString()));
} // Shifts C_i, D_i vectors
NotBitArray F(NotBitArray B, NotBitArray K)
{
NotBitArray E_B = Permutation(B, E_table); // Extending
E_B = E_B.Xor(K);
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 8; i++)
{
NotBitArray B_i = new NotBitArray(E_B.bits.Substring(i * 6, 6)); // Get 6bit vector
NotBitArray S_i = S(i, B_i); // Change to 4bit
sb.Append(S_i.bits); // Add to result
}
return(Permutation(new NotBitArray(sb.ToString()), P_table)); // Final premutation for F(R_i, K_i)
}
byte[] DES(byte[] byte_block, byte[] byte_key, int round_count, bool is_encoding)
{
NotBitArray key = new NotBitArray(byte_key);
NotBitArray block = new NotBitArray(byte_block);
NotBitArray CD_i = Permutation(key, G_table); // C_0 + D_0
NotBitArray[] Keys = new NotBitArray[round_count];
for (int i = 0; i < round_count; i++)
{
CD_i = Get_CD_i(i, CD_i);
Keys[i] = Permutation(CD_i, H_table);
}
NotBitArray Output = Coding_rounds(round_count, block, Keys, is_encoding);
return(Output.ToByteArray());
}
public NotBitArray Xor(NotBitArray block)
{
StringBuilder sb = new StringBuilder();
for (int i = 0; i < bits.Length; i++)
{
if (this[i] == block[i])
{
sb.Append('0');
}
else
{
sb.Append('1');
}
}
return(new NotBitArray(sb.ToString()));
}
} // Shifts C_i, D_i vectors
NotBitArray S(int i, NotBitArray B_i)
{
int a = 0, b = 0;
a += B_i[0] ? 2 : 0;
a += B_i[5] ? 1 : 0;
for (int b_count = 0; b_count < 4; b_count++)
{
b += B_i[4 - b_count] ? 1 << b_count : 0;
}
int[][] S_table;
switch (i)
{
case 0:
{
S_table = new int[4][]
{
new int[16] {
14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7
},
new int[16] {
0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8
},
new int[16] {
4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0
},
new int[16] {
15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13
}
};
break;
}
case 1:
{
S_table = new int[4][]
{
new int[16] {
15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10
},
new int[16] {
3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5
},
new int[16] {
0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15
},
new int[16] {
13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9
}
};
break;
}
case 2:
{
S_table = new int[4][]
{
new int[16] {
10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8
},
new int[16] {
13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1
},
new int[16] {
13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7
},
new int[16] {
1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12
}
};
break;
}
case 3:
{
S_table = new int[4][]
{
new int[16] {
7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15
},
new int[16] {
13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9
},
new int[16] {
10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4
},
new int[16] {
3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14
}
};
break;
}
case 4:
{
S_table = new int[4][]
{
new int[16] {
2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9
},
new int[16] {
14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6
},
new int[16] {
4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14
},
new int[16] {
11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3
}
};
break;
}
case 5:
{
S_table = new int[4][]
{
new int[16] {
12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11
},
new int[16] {
10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8
},
new int[16] {
9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6
},
new int[16] {
4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13
}
};
break;
}
case 6:
{
S_table = new int[4][]
{
new int[16] {
4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1
},
new int[16] {
13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6
},
new int[16] {
1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2
},
new int[16] {
6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12
}
};
break;
}
case 7:
{
S_table = new int[4][]
{
new int[16] {
13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7
},
new int[16] {
1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2
},
new int[16] {
7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8
},
new int[16] {
2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11
}
};
break;
}
default: return(null);
}
; // Get S table for i's B
int B_out = S_table[a][b];
StringBuilder sb = new StringBuilder();
for (int c = 0; c < 4; c++)
{
sb.Append((B_out & (1 << c)) != 0 ? '1' : '0');
}
return(new NotBitArray(sb.ToString()));
}
