2 use std
::io
::TcpStream
;
3 use std
::iter
::range_inclusive
;
4 use std
::slice
::bytes
::copy_memory
;
6 use packet
::{ Packet
, Error
};
7 use end_point
::EndPoint
;
9 /// Try to decipher a ciphered data block by using the previous XOR operand and an oracle on the provided address and port.
10 /// May print some messages on stdout.
11 pub fn decipher(address
: &str, port
: u16, original_xor_operand
: &[u8, ..16], cipher_block
: &[u8, ..16], variant
: packet
::Variant
) -> Option
<Vec
<u8>> {
12 let mut end_point
= EndPoint
::new(
13 match TcpStream
::connect(address
, port
) {
16 println!("Unable to connect to the oracle on [{}]:{}", address
, port
);
23 // See 'packet::Packet' documentation for a complete description about the binary packet structure.
24 let mut final_packet
= [0u8, ..2 + 1 + 8 + 32 + 10];
25 final_packet
[1] = (final_packet
.len() as u8) - 2; // Data length.
26 copy_memory(final_packet
.slice_mut(2 + 1 + 8 + 16, 2 + 1 + 8 + 32), cipher_block
);
28 let mut decipher_block
= [0u8, ..16]; // The result.
29 let mut x_prime_block
= [0u8, ..16]; // The cipher block ('cipher_block') after AES and before XOR.
30 let mut current_timestamp
= 0u64;
31 let mut first_byte
= 0u8; // Used to save the first byte for the first iteration.
34 fn forged_xor_operand(packet
: &mut [u8]) -> &mut [u8] { packet
.slice_mut(2 + 1 + 8, 2 + 1 + 8 + 16) }
39 let mut get_mac_mismatch_error
= false; // For the first byte we need to insure there is only one AUTH error (one valid padding).
41 for v
in range_inclusive(0u8, 255) { // For each values of the current byte.
43 // Compute and write timestamp.
44 current_timestamp
+= 2;
46 let mut timestamp_writer
= io
::BufWriter
::new(final_packet
.slice_mut(2 + 1, 2 + 1 + 8));
47 let _
= timestamp_writer
.write_be_u64(current_timestamp
- 1);
50 forged_xor_operand(&mut final_packet
)[byte
] = v
;
52 match end_point
.send_raw_with_result(final_packet
) {
53 Ok(Ok(p @ Packet
{ t
: Error(packet
::AuthError
), .. })) => {
54 println!("We received a MAC Error: {}", p
);
56 // If we already got a MAC mismatch for the first byte then
57 // the second byte is incremented and the main loop is replayed for the first byte.
58 if byte
== 15 && get_mac_mismatch_error
{
59 forged_xor_operand(&mut final_packet
)[14] += 1;
63 get_mac_mismatch_error
= true;
65 let padding_value
= 16 - byte
;
66 x_prime_block
[byte
] = v ^
(padding_value
as u8);
67 decipher_block
[byte
] = x_prime_block
[byte
] ^ original_xor_operand
[byte
];
69 // We set the processed bytes of the forged XOR operand to have the next padding value (2, 3, 4, etc..).
70 for i
in range(16 - padding_value
, 16) {
71 forged_xor_operand(&mut final_packet
)[i
] = x_prime_block
[i
] ^
((padding_value
as u8) + 1);
74 // Special case for the first byte: we have to test all the values to avoid a valid padding
75 // which is not [.., 0x01], for instance [.., 0x02, 0x02]. It's a very rare case but not impossible.
77 first_byte
= forged_xor_operand(&mut final_packet
)[15];
82 Ok(Ok(Packet
{ t
: Error(packet
::CryptError
), .. })) => (), // Ignored case: the padding is wrong.
84 println!("Unexcepted response, aborting. {}", other
);
91 forged_xor_operand(&mut final_packet
)[15] = first_byte
;
94 // It was the last byte.
95 if byte
== 0 { break; }
100 Some(decipher_block
.to_vec())