diff options
| -rw-r--r-- | src/crack.rs | 60 | ||||
| -rw-r--r-- | tests/lib.rs | 3 |
2 files changed, 34 insertions, 29 deletions
diff --git a/src/crack.rs b/src/crack.rs index 523c7e8..344488b 100644 --- a/src/crack.rs +++ b/src/crack.rs @@ -71,38 +71,14 @@ pub fn crack_repeating_key_xor (input: &[u8]) -> Vec<u8> { let mut min_diff = 100.0; let mut best_key = vec![]; for (keysize, _) in keysizes { - let strides: Vec<Vec<u8>> = (0..keysize) - .map(|n| { - // XXX sigh ): - let mut elts = vec![]; - for (i, &c) in input.iter().enumerate() { - if i % keysize == n { - elts.push(c); - } - } - elts - }) - .collect(); - let cracked: Vec<(u8, f64)> = strides - .iter() - .map(|input| crack_single_byte_xor_with_confidence(input)) - .collect(); - let diff = cracked - .iter() - .map(|&(_, diff)| diff) - .fold(0.0, |acc, x| acc + x); - let key = cracked - .iter() - .map(|&(c, _)| c) - .collect(); - let normal_diff = diff / (keysize as f64); - if normal_diff < min_diff { - min_diff = normal_diff; + let (key, diff) = crack_repeating_key_xor_with_keysize(input, keysize); + if diff < min_diff { + min_diff = diff; best_key = key; } } - return repeating_key_xor(input, &best_key[..]); + return best_key; } pub fn find_aes_128_ecb_encrypted_string (inputs: &[Vec<u8>]) -> Vec<u8> { @@ -378,6 +354,34 @@ fn crack_single_byte_xor_with_confidence (input: &[u8]) -> (u8, f64) { return (best_key, min_diff); } +fn crack_repeating_key_xor_with_keysize (input: &[u8], keysize: usize) -> (Vec<u8>, f64) { + let strides: Vec<Vec<u8>> = (0..keysize) + .map(|n| { + // XXX sigh ): + let mut elts = vec![]; + for (i, &c) in input.iter().enumerate() { + if i % keysize == n { + elts.push(c); + } + } + elts + }) + .collect(); + let cracked: Vec<(u8, f64)> = strides + .iter() + .map(|input| crack_single_byte_xor_with_confidence(input)) + .collect(); + let diff = cracked + .iter() + .map(|&(_, diff)| diff) + .fold(0.0, |acc, x| acc + x); + let key = cracked + .iter() + .map(|&(c, _)| c) + .collect(); + return (key, diff / (keysize as f64)); +} + fn count_duplicate_blocks (input: &[u8], block_size: usize) -> usize { let mut set = HashSet::new(); let mut dups = 0; diff --git a/tests/lib.rs b/tests/lib.rs index 08fb2a9..65380cf 100644 --- a/tests/lib.rs +++ b/tests/lib.rs @@ -105,7 +105,8 @@ fn problem_5 () { fn problem_6 () { let ciphertext = read_as_base64("data/6.txt"); let plaintext = read("data/6.out.txt"); - let got = matasano::crack_repeating_key_xor(&ciphertext[..]); + let key = matasano::crack_repeating_key_xor(&ciphertext[..]); + let got = matasano::repeating_key_xor(&ciphertext[..], &key[..]); assert_eq!(got, plaintext); } |