Thread: Altering Encryption to block clients

Description: Change the encryption on the client and server to block unwanted clients.

Difficulty: -1

Assumed Knowledge: Basic number changing, Memory.

Tested Server: Winterloves.

Files/Classes Modified: You will need a client and a server for this to work

Procedure
Step 1: [i]For this to work you need to have your own personal client.
Open class17 client side to open the clients encryption.

It should look like this
[php]
public final class Class17
{

public Class17(int i, int ai[])
{
anInt332 = -436;
anInt333 = -431;
anIntArray336 = new int[256];
anIntArray335 = new int[256];
for(int j = 0; j < ai.length; j++)
anIntArray335[j] = ai[j];

if(i >= 0)
anInt333 = -242;
method248();
}

public final int method246()
{
if(anInt334-- == 0)
{
method247();
anInt334 = 255;
}
return anIntArray335[anInt334];
}

private final void method247()
{
anInt338 += ++anInt339;
for(int i = 0; i < 256; i++)
{
int j = anIntArray336[i];
if((i & 3) == 0)
anInt337 ^= anInt337 << 13;
else
if((i & 3) == 1)
anInt337 ^= anInt337 >>> 6;
else
if((i & 3) == 2)
anInt337 ^= anInt337 << 2;
else
if((i & 3) == 3)
anInt337 ^= anInt337 >>> 16;
anInt337 += anIntArray336[i + 128 & 0xff];
int k;
anIntArray336[i] = k = anIntArray336[(j & 0x3fc) >> 2] + anInt337 + anInt338;
anIntArray335 = anInt338 = anIntArray336[(k >> 8 & 0x3fc) >> 2] + j;
}

}

private final void method248()
{
int i1;
int j1;
int k1;
int l1;
int i2;
int j2;
int k2;
int l = i1 = j1 = k1 = l1 = i2 = j2 = k2 = 0x9e3779b9;
for(int i = 0; i < 4; i++)
{
l ^= i1 << 11;
k1 += l;
i1 += j1;
i1 ^= j1 >>> 2;
l1 += i1;
j1 += k1;
j1 ^= k1 << 8;
i2 += j1;
k1 += l1;
k1 ^= l1 >>> 16;
j2 += k1;
l1 += i2;
l1 ^= i2 << 10;
k2 += l1;
i2 += j2;
i2 ^= j2 >>> 4;
l += i2;
j2 += k2;
j2 ^= k2 << 8;
i1 += j2;
k2 += l;
k2 ^= l >>> 9;
j1 += k2;
l += i1;
}

for(int j = 0; j < 256; j += 8)
{
l += anIntArray335[j];
i1 += anIntArray335[j + 1];
j1 += anIntArray335[j + 2];
k1 += anIntArray335[j + 3];
l1 += anIntArray335[j + 4];
i2 += anIntArray335[j + 5];
j2 += anIntArray335[j + 6];
k2 += anIntArray335[j + 7];
l ^= i1 << 11;
k1 += l;
i1 += j1;
i1 ^= j1 >>> 2;
l1 += i1;
j1 += k1;
j1 ^= k1 << 8;
i2 += j1;
k1 += l1;
k1 ^= l1 >>> 16;
j2 += k1;
l1 += i2;
l1 ^= i2 << 10;
k2 += l1;
i2 += j2;
i2 ^= j2 >>> 4;
l += i2;
j2 += k2;
j2 ^= k2 << 8;
i1 += j2;
k2 += l;
k2 ^= l >>> 9;
j1 += k2;
l += i1;
anIntArray336[j] = l;
anIntArray336[j + 1] = i1;
anIntArray336[j + 2] = j1;
anIntArray336[j + 3] = k1;
anIntArray336[j + 4] = l1;
anIntArray336[j + 5] = i2;
anIntArray336[j + 6] = j2;
anIntArray336[j + 7] = k2;
}

for(int k = 0; k < 256; k += 8)
{
l += anIntArray336[k];
i1 += anIntArray336[k + 1];
j1 += anIntArray336[k + 2];
k1 += anIntArray336[k + 3];
l1 += anIntArray336[k + 4];
i2 += anIntArray336[k + 5];
j2 += anIntArray336[k + 6];
k2 += anIntArray336[k + 7];
l ^= i1 << 11;
k1 += l;
i1 += j1;
i1 ^= j1 >>> 2;
l1 += i1;
j1 += k1;
j1 ^= k1 << 8;
i2 += j1;
k1 += l1;
k1 ^= l1 >>> 16;
j2 += k1;
l1 += i2;
l1 ^= i2 << 10;
k2 += l1;
i2 += j2;
i2 ^= j2 >>> 4;
l += i2;
j2 += k2;
j2 ^= k2 << 8;
i1 += j2;
k2 += l;
k2 ^= l >>> 9;
j1 += k2;
l += i1;
anIntArray336[k] = l;
anIntArray336[k + 1] = i1;
anIntArray336[k + 2] = j1;
anIntArray336[k + 3] = k1;
anIntArray336[k + 4] = l1;
anIntArray336[k + 5] = i2;
anIntArray336[k + 6] = j2;
anIntArray336[k + 7] = k2;
}

method247();
anInt334 = 256;
}

private int anInt332;
private int anInt333;
private int anInt334;
private int anIntArray335[];
private int anIntArray336[];
private int anInt337;
private int anInt338;
private int anInt339;
}
[/php]


Step 2: All there is to do is change a variable around in that code.

In Cryption.java server side change the exact same number!
The best place to change is this method
[php]
public void initializeKeySet()
{
int i1;
int j1;
int k1;
int l1;
int i2;
int j2;
int k2;
int l = i1 = j1 = k1 = l1 = i2 = j2 = k2 = 0x9e3779b9;
for(int i = 0; i < 4; i++)
{
l ^= i1 << 11;
k1 += l;
i1 += j1;
i1 ^= j1 >>> 2;
l1 += i1;
j1 += k1;
j1 ^= k1 << 8;
i2 += j1;
k1 += l1;
k1 ^= l1 >>> 16;
j2 += k1;
l1 += i2;
l1 ^= i2 << 10;
k2 += l1;
i2 += j2;
i2 ^= j2 >>> 4;
l += i2;
j2 += k2;
j2 ^= k2 << 8;
i1 += j2;
k2 += l;
k2 ^= l >>> 9;
j1 += k2;
l += i1;
}

for(int j = 0; j < 256; j += 8)
{
l += keySetArray[j];
i1 += keySetArray[j + 1];
j1 += keySetArray[j + 2];
k1 += keySetArray[j + 3];
l1 += keySetArray[j + 4];
i2 += keySetArray[j + 5];
j2 += keySetArray[j + 6];
k2 += keySetArray[j + 7];
l ^= i1 << 11;
k1 += l;
i1 += j1;
i1 ^= j1 >>> 2;
l1 += i1;
j1 += k1;
j1 ^= k1 << 8;
i2 += j1;
k1 += l1;
k1 ^= l1 >>> 16;
j2 += k1;
l1 += i2;
l1 ^= i2 << 10;
k2 += l1;
i2 += j2;
i2 ^= j2 >>> 4;
l += i2;
j2 += k2;
j2 ^= k2 << 8;
i1 += j2;
k2 += l;
k2 ^= l >>> 9;
j1 += k2;
l += i1;
cryptArray[j] = l;
cryptArray[j + 1] = i1;
cryptArray[j + 2] = j1;
cryptArray[j + 3] = k1;
cryptArray[j + 4] = l1;
cryptArray[j + 5] = i2;
cryptArray[j + 6] = j2;
cryptArray[j + 7] = k2;
}

for(int k = 0; k < 256; k += 8)
{
l += cryptArray[k];
i1 += cryptArray[k + 1];
j1 += cryptArray[k + 2];
k1 += cryptArray[k + 3];
l1 += cryptArray[k + 4];
i2 += cryptArray[k + 5];
j2 += cryptArray[k + 6];
k2 += cryptArray[k + 7];
l ^= i1 << 11;
k1 += l;
i1 += j1;
i1 ^= j1 >>> 2;
l1 += i1;
j1 += k1;
j1 ^= k1 << 8;
i2 += j1;
k1 += l1;
k1 ^= l1 >>> 16;
j2 += k1;
l1 += i2;
l1 ^= i2 << 10;
k2 += l1;
i2 += j2;
i2 ^= j2 >>> 4;
l += i2;
j2 += k2;
j2 ^= k2 << 8;
i1 += j2;
k2 += l;
k2 ^= l >>> 9;
j1 += k2;
l += i1;
cryptArray[k] = l;
cryptArray[k + 1] = i1;
cryptArray[k + 2] = j1;
cryptArray[k + 3] = k1;
cryptArray[k + 4] = l1;
cryptArray[k + 5] = i2;
cryptArray[k + 6] = j2;
cryptArray[k + 7] = k2;
}

generateNextKeySet();
keyArrayIdx = 256;
}
[/php]
(It must be the same as Cliet side!)

NOTE: Remember which one you changed!

In my client and server i changed
[php]
int l = i1 = j1 = k1 = l1 = i2 = j2 = k2 = 0x9e3779b9;
[/php]
To
[php]
int l = i1 = j1 = k1 = l1 = i2 = j2 = k2 = 0x9e3769b9;
[/php]

I tested it with four clients and not one could connect with me



Step 3: Now is any client tries to connect to the server without the same encryption the client will get a t1 error and disconnect.
Its that simple



Credits: Jagex for the client.