diff options
author | Jesse Luehrs <doy@tozt.net> | 2015-04-05 23:49:25 -0400 |
---|---|---|
committer | Jesse Luehrs <doy@tozt.net> | 2015-04-05 23:49:33 -0400 |
commit | d895cc4c9687cd88b10d34b418eac990091fc8bd (patch) | |
tree | cf6118955ca65d6937e09f761474bc048240425e | |
parent | f955edd17464fb35df86e07bb2c3076b7e1274d8 (diff) | |
download | matasano-d895cc4c9687cd88b10d34b418eac990091fc8bd.tar.gz matasano-d895cc4c9687cd88b10d34b418eac990091fc8bd.zip |
problem 24, part 1
-rw-r--r-- | src/crack.rs | 15 | ||||
-rw-r--r-- | src/lib.rs | 1 | ||||
-rw-r--r-- | tests/lib.rs | 17 |
3 files changed, 33 insertions, 0 deletions
diff --git a/src/crack.rs b/src/crack.rs index 92950c4..b351249 100644 --- a/src/crack.rs +++ b/src/crack.rs @@ -386,6 +386,21 @@ pub fn clone_mersenne_twister_from_output (outputs: &[u32]) -> MersenneTwister { return MersenneTwister::from_seed((state, 0)); } +pub fn recover_16_bit_mt19937_key (ciphertext: &[u8], suffix: &[u8]) -> Option<u16> { + for _key in 0..65536u32 { + let key = _key as u16; + let plaintext = ::random::mt19937_stream_cipher( + ciphertext, + key as u32 + ); + if &plaintext[(ciphertext.len() - suffix.len())..] == suffix { + return Some(key); + } + } + + return None; +} + fn crack_single_byte_xor_with_confidence (input: &[u8]) -> (u8, f64) { let mut min_diff = 100.0; let mut best_key = 0; @@ -37,3 +37,4 @@ pub use crack::crack_single_byte_xor; pub use crack::crack_repeating_key_xor; pub use crack::crack_fixed_nonce_ctr_statistically; pub use crack::clone_mersenne_twister_from_output; +pub use crack::recover_16_bit_mt19937_key; diff --git a/tests/lib.rs b/tests/lib.rs index 71c5e32..f498e1f 100644 --- a/tests/lib.rs +++ b/tests/lib.rs @@ -483,3 +483,20 @@ fn problem_22 () { assert_eq!(mt.gen::<u32>(), mt2.gen::<u32>()); } } + +#[test] +fn problem_23 () { + let key: u16 = rand::thread_rng().gen(); + let fixed_suffix = b"AAAAAAAAAAAAAA"; + let plaintext: Vec<u8> = rand::thread_rng() + .gen_iter() + .take(rand::thread_rng().gen_range(0, 32)) + .chain(fixed_suffix.iter().map(|x| *x)) + .collect(); + let ciphertext = matasano::mt19937_stream_cipher(&plaintext[..], key as u32); + let got = matasano::recover_16_bit_mt19937_key( + &ciphertext[..], + &fixed_suffix[..], + ).unwrap(); + assert_eq!(got, key); +} |