encrypt.h File Reference

#include <stdint.h>
#include <stddef.h>
#include <stdlib.h>
#include "eolib/rng.h"

Go to the source code of this file.

Functions
static int32_t	eo_generate_server_verification_challenge ()
int32_t	eo_server_verification_hash (int32_t challenge)
void	eo_swap_multiples (uint8_t *data, size_t length, uint8_t multiple)
uint8_t	eo_generate_swap_multiple ()
void	eo_encrypt_packet (uint8_t *data, size_t length, uint8_t swap_multiple)
void	eo_decrypt_packet (uint8_t *data, size_t length, uint8_t swap_multiple)

Function Documentation

eo_decrypt_packet()

void eo_decrypt_packet	(	uint8_t *	data,
		size_t	length,
		uint8_t	swap_multiple )

Decrypts a packet in place using the specified swap multiple.

Parameters

data	The packet data to decrypt.
length	Number of bytes in data.
swap_multiple	The swap multiple for the packet.

Definition at line 114 of file encrypt.c.

eo_encrypt_packet()

void eo_encrypt_packet	(	uint8_t *	data,
		size_t	length,
		uint8_t	swap_multiple )

Encrypts a packet in place using the specified swap multiple.

Parameters

data	The packet data to encrypt.
length	Number of bytes in data.
swap_multiple	The swap multiple for the packet.

Definition at line 58 of file encrypt.c.

eo_generate_server_verification_challenge()

int32_t eo_generate_server_verification_challenge ( )

inlinestatic

Generates a server verification challenge value, which is a random integer used in the EO protocol's challenge-response authentication process. The client receives this challenge from the server and must compute the correct response using the eo_server_verification_hash function to authenticate itself to the server.

Returns

The generated server verification challenge value.

Remarks

Emulates the behavior of the original game client: eo_rand() % 1000000

Definition at line 17 of file encrypt.h.

eo_generate_swap_multiple()

uint8_t eo_generate_swap_multiple

(

)

Generates a cryptographically random swap multiple between 6 and 12 inclusive.

Returns

The generated swap multiple.

Definition at line 53 of file encrypt.c.

eo_server_verification_hash()

int32_t eo_server_verification_hash

(

int32_t

challenge

)

Calculates the server verification hash for the given challenge value.

Parameters

challenge

The server challenge value (from ServerInitInitServerPacket).

Returns

The verification hash to be sent back to the server.

Remarks

Implements the EO protocol challenge-response formula: hash = 110905 + ((c%9)+1) * ((11092004-c) % (((c%11)+1)*119)) * 119 + (c%2004) where c = challenge + 1. The constants are protocol-defined magic values.

Definition at line 5 of file encrypt.c.

eo_swap_multiples()

void eo_swap_multiples	(	uint8_t *	data,
		size_t	length,
		uint8_t	multiple )

Reverses contiguous sequences of bytes where each value is a multiple of multiple.

Parameters

data	The packet data to mutate.
length	Number of bytes in data.
multiple	The divisor used to determine which bytes are in a sequence.

Definition at line 12 of file encrypt.c.