public int auth_client(byte[] givenusername)
{
int kdnr = 0;
for(kdnr=0;kdnr<kundendb.Length;kdnr++)
{
MD5 uname = new MD5CryptoServiceProvider();
ASCIIEncoding uname_md5_encoding=new ASCIIEncoding();
byte[] uname_md5 = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
uname_md5 = uname.ComputeHash(uname_md5_encoding.GetBytes(kundendb[kdnr].usr));
uname.Clear();
//ASCIIEncoding crc32_encoding = new ASCIIEncoding();
CRC32 crc = new CRC32(0xedb88320); // equivalent to new CRC32(CRC32.DefaultPolynomial);
byte[] uname_crc32 = { 0, 0, 0, 0 };
uname_crc32 = crc.ComputeHash(uname_md5);
crc.Clear();
if((givenusername[0]==uname_crc32[0]) && (givenusername[1]==uname_crc32[1]) &&(givenusername[2]==uname_crc32[2]) &&(givenusername[3]==uname_crc32[3]))
{
return kdnr;
}
}
return -1; //lets return the "kundennummer" of the right viewer
}
public void RangeTest()
{
byte[] sample = new byte[10000];
const int delta = 19;
new System.Random().NextBytes(sample);
byte[] sample2 = new byte[10];
for(int i=0; i<10; i++)
{
sample2[i] = sample[i+delta];
}
CRC32 expected = new CRC32();
expected.ComputeHash(sample2, 0, 10);
CRC32 actual = new CRC32();
actual.ComputeHash(sample, delta, 10);
Assert.AreEqual(BitConverter.ToString(expected.Hash), BitConverter.ToString(actual.Hash));
}
public void MethodsTest()
{
byte[] sample = new byte[10000];
new System.Random().NextBytes(sample);
CRC32 a1 = new CRC32();
CRC32 a2 = new CRC32();
CRC32 a3 = new CRC32();
CRC32 a4 = new CRC32();
//method1
byte[] a1Hash = a1.ComputeHash(sample);
//method2
a2.TransformFinalBlock(sample, 0, 10000);
byte[] a2Hash = a2.Hash;
//method3
for(int i=0; i<10000; i+=1000)
{
a3.TransformBlock(sample, i, 1000, sample, i);
}
a3.TransformFinalBlock(sample, 0, 0);
byte[] a3Hash = a3.Hash;
//method4
for(int i=0; i<10000; i+=1000)
{
if (i == 9000)
a4.TransformFinalBlock(sample, i, 1000);
else
a4.TransformBlock(sample, i, 1000, sample, i);
}
byte[] a4Hash = a4.Hash;
Assert.AreEqual(BitConverter.ToString(a1Hash), BitConverter.ToString(a2Hash), "Method a2 failed");
Assert.AreEqual(BitConverter.ToString(a1Hash), BitConverter.ToString(a3Hash), "Method a3 failed");
Assert.AreEqual(BitConverter.ToString(a1Hash), BitConverter.ToString(a4Hash), "Method a4 failed");
}
public int validate_request(byte[] message)
{
int i=0;
switch(message[0])
{
case 0:
{
byte length = message[1];
byte[] datacrc = new byte[4];
byte[] data = new byte[length];
Array.Copy(message,4,datacrc,0,4);
Array.Copy(message,20,data,0,length);
CRC32 crc = new CRC32(0xedb88320);
byte[] data_crc32 = crc.ComputeHash(data);
for(i=0;i<4;i++)
{
if(datacrc[i]!=data_crc32[i])
{
return -1; //crc not correct - data broken !
}
}
return 1; // data is ok, we can proceed ...
}
case 2:
{
return 0; //not implemented yet
}
}
return -1;
}
public byte[] generate_cwanswer(byte[] checksum, byte[] message, byte[] cw, string key)
{
byte[] cwanswer = new byte[48];
byte[] cryptedanswer = new byte[52];
MemoryStream ms = new MemoryStream();
CRC32 crc = new CRC32(0xedb88320); // equivalent to new CRC32(CRC32.DefaultPolynomial);
byte[] cw_crc32 = crc.ComputeHash(cw);
//Array.Copy(checksum,0,cwanswer,0,4);
Array.Copy(message,0,cwanswer,0,20);
Array.Copy(cw_crc32,0,cwanswer,4,4);
Array.Copy(cw,0,cwanswer,20,16);
cwanswer[0] = 0x01;
cwanswer[1] = 0x10;
cwanswer[2] = 0x32;
cwanswer[3] = 0x84;
for(int i=0;i<12;i++)
cwanswer[i+36] = 0xFF;
MD5 passwd = new MD5CryptoServiceProvider();
ASCIIEncoding passwd_md5_encoding=new ASCIIEncoding();
byte[] passwd_md5 = passwd.ComputeHash(passwd_md5_encoding.GetBytes(key));
RijndaelManaged aes = new RijndaelManaged();
aes.Mode = CipherMode.ECB;
aes.BlockSize = 128;
aes.KeySize = 128; //128-Bit AES En/Decryption
aes.Key = passwd_md5;
CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write);
cs.Write(cwanswer, 0, 48);
aes.Clear();
byte[] cryptedData = ms.ToArray();
Array.Copy(cryptedData,0,cryptedanswer,4,48);
Array.Copy(checksum,0,cryptedanswer,0,4);
return cryptedanswer;
}
