Forging Packets

I think I need to RC4 every packet before I send it? Correct
What packets do I receive are in RC4 that I need to decrypt? Is it all of them? Yup
I know I can look at K Relay for packet structures but I'm kind of lost on what needs to be put in some of them. Each packet has it's own structure. Hello packet has 10 strings, 4 ints and a byte array that need to be filled. Example of a structure:

What packets should I look into making after I figure out the hello packet? After sending the hello packet you receive the MapInfo packet

Maybe others that have reversed rotmg can give a better understanding of the other questions.

What about this question: Do I also encrypt the packet ID along with the packet data?

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I think @krazyshank could help here.

So here's what I got so far from looking at the K Relay source:

• There is an empty 4 bytes at the beginning of the packet for god knows what reason.
• The fifth byte is the packet ID.
• I've been doing strings in ASCII but Kronk has been doing them in UTF8, I don't know if there is much of a difference between those but I will switch to UTF8.
• I encrypt the whole packet with the RC4 cipher and decrypt all the data in all incoming packets with the same cipher but a different key.
• All the numbers that are written are in network order (big endian).

For the love of god, please correct me if I'm wrong.

First four bytes aren't empty, they're the length of the packet.
UTF8 is the correct string format, there would be big issues if you didnt use it.
You need two ciphers, one for each key, seperate instances. The RC4 cipher has a state so what it has decrypted beforehand changes its output and internal state, so you must always use the correct one for incomming and outgoing packets.
Yeah you need to convert to to whatever order the network is currently using.

First four bytes aren't empty, they're the length of the packet.
UTF8 is the correct string format, there would be big issues if you didnt use it.
You need two ciphers, one for each key, seperate instances. The RC4 cipher has a state so what it has decrypted beforehand changes its output and internal state, so you must always use the correct one for incomming and outgoing packets.
Yeah you need to convert to to whatever order the network is currently using.

I love your concern about the RC4 cipher, but I'm not using yours. I made my own using bouncy castle and I already got that encryption and decryption with different keys thing sorted.

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I have another worry, it's null terminated strings. How do I handle strings? Like, when I GetBytes() on a string it doesn't give me the null terminated character so I manually add that in, but reading your code you seem to also have a function for writing a string in a different encoding that also prefixes it with it's length. My biggest concern with this is when I encrypt the guid and password do I encrypt the strings without the null character then add it in afterwards or what. I just need to get this right or I will never be able to connect xd

Maybe others that have reversed rotmg can give a better understanding of the other questions.