public bool Decode(byte[] data, int len, string key)
{
blf_ctx c;
uint xl, xr;
int i;
if (len % 8 != 0)
{
return(false);
}
c = new blf_ctx();
c.S = new uint[4, 256];
c.P = new uint[18];
InitBlowfish(c, key, key.Length);
for (i = 0; i < len; i += 8)
{
// memcpy(&xl, data + i, sizeof(UINT32));
// memcpy(&xr, data + i + 4, sizeof(UINT32));
xl = (uint)ConvertHelper.BytesToInt32(data, i, true);
xr = (uint)ConvertHelper.BytesToInt32(data, i + 4, true);
Blowfish_decipher(c, ref xl, ref xr);
//memcpy(data + i, &xl, sizeof(UINT32));
//memcpy(data + i + 4, &xr, sizeof(UINT32));
byte[] byteXl = ConvertHelper.Int32ToBytes((int)xl, true);
byte[] byteXr = ConvertHelper.Int32ToBytes((int)xr, true);
Array.Copy(byteXl, 0, data, i, 4);
Array.Copy(byteXr, 0, data, i + 4, 4);
}
return(true);
}
private void Blowfish_decipher(blf_ctx c, ref uint xl, ref uint xr)
{
uint Xl;
uint Xr;
uint temp;
int i;
Xl = xl;
Xr = xr;
for (i = ROUNDCOUNT + 1; i > 1; --i)
{
Xl = Xl ^ c.P[i];
Xr = F1(c, Xl) ^ Xr;
temp = Xl;
Xl = Xr;
Xr = temp;
}
temp = Xl;
Xl = Xr;
Xr = temp;
Xr = Xr ^ c.P[1];
Xl = Xl ^ c.P[0];
xl = Xl;
xr = Xr;
}
private void InitBlowfish(blf_ctx c, string key, int key_len)
{
//short error;
//short numread;
uint data;
uint data1;
uint datar;
/* Initialize s-boxes without file read. */
int i;
ushort j = 0;
int k;
for (i = 0; i < 256; i++)
{
c.S[0, i] = ks0[i];
c.S[1, i] = ks1[i];
c.S[2, i] = ks2[i];
c.S[3, i] = ks3[i];
}
for (i = 0; i < 18; i++)
{
c.P[i] = 0;
}
for (i = 0; i < ROUNDCOUNT + 2; ++i)
{
data = 0x00000000;
for (k = 0; k < 4; ++k)
{
data = (data << 8) | key[j];
j++;
if (j >= key_len)
{
j = 0;
}
} // for k
c.P[i] = c.P[i] ^ data;
} //for i
data1 = 0x00000000;
datar = 0x00000000;
for (i = 0; i < ROUNDCOUNT + 2; i += 2)
{
Blowfish_encipher(c, ref data1, ref datar);
c.P[i] = data1;
c.P[i + 1] = datar;
}
for (i = 0; i < 4; ++i)
{
for (j = 0; j < 256; j += 2)
{
Blowfish_encipher(c, ref data1, ref datar);
c.S[i, j] = data1;
c.S[i, j + 1] = datar;
} //for j
} //for i
}
private void Blowfish_encipher(blf_ctx c, ref uint xl, ref uint xr)
{
uint Xl;
uint Xr;
uint temp;
int i;
Xl = xl;
Xr = xr;
for (i = 0; i < ROUNDCOUNT; ++i)
{
Xl = Xl ^ c.P[i];
Xr = F1(c, Xl) ^ Xr;
temp = Xl;
Xl = Xr;
Xr = temp;
}
temp = Xl;
Xl = Xr;
Xr = temp;
Xr = Xr ^ c.P[ROUNDCOUNT];
Xl = Xl ^ c.P[ROUNDCOUNT + 1];
xl = Xl;
xr = Xr;
}
private static uint F1(blf_ctx bc, uint x)
{
ushort a;
ushort b;
ushort c;
ushort d;
uint y;
d = (ushort)((ushort)x & 0x00FF);
x >>= 8;
c = (ushort)((ushort)x & 0x00FF);
x >>= 8;
b = (ushort)((ushort)x & 0x00FF);
x >>= 8;
a = (ushort)((ushort)x & 0x00FF);
y = bc.S[0, a] + bc.S[1, b];
y = y ^ bc.S[2, c];
y = y + bc.S[3, d];
return(y);
}
