felixm/cryptopals
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Two out of four untemper parts work.

Browse Source
This commit is contained in:
Felix Martin
2022-08-06 10:19:00 -04:00
parent 92c73fb125
commit b7ca276f72
1 changed files with 38 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files

69
src/set3.rs
View File

@@ -359,50 +359,51 @@ pub fn challenge22() {
}
pub fn challenge23() {
// Once you have "untemper" working, create a new MT19937 generator, tap it for 624 outputs,
/*
let mut mt = mt19937::MT19937::new();
let seed: u32 = rand::thread_rng().gen::<u32>();
mt.seed(seed);
let outputs: Vec<u32> = (0..624).map(|_| mt.extract_number()).collect();
*/
fn temper(x: u32) -> u32 {
//const S: u32 = 7;
//const T: u32 = 15;
//const U: u32 = 11;
//const B: u32 = 0x9D2C5680;
//const C: u32 = 0xEFC60000;
//const L: u32 = 18;
const S: u32 = 7;
// const T: u32 = 15;
// const U: u32 = 11;
const B: u32 = 0x9D2C5680;
// const C: u32 = 0xEFC60000;
// const L: u32 = 18;
let mut y = x;
// y = y ^ (y >> U);
// y = y ^ ((y << S) & B);
y = y ^ ((y << S) & B);
// y = y ^ ((y << T) & C);
// y = y ^ (y >> L);
y = y ^ (y >> 24);
y
}
fn untemper(x: u32) -> u32 {
//const S: u32 = 7;
//const T: u32 = 15;
//const U: u32 = 11;
//const B: u32 = 0x9D2C5680;
//const C: u32 = 0xEFC60000;
//const L: u32 = 18;
const M: u32 = 32;
let mut y = x;
//y = y ^ (y >> U);
//y = y ^ ((y << S) & B);
//y = y ^ ((y << T) & C);
//y = y ^ (y >> L);
// xxxx'yyyy
// ^0000'xxxx
// xxxx'zzzz
println!("{:#010x}", u32::MAX << 11 );
y = (y & 0xffffff00) | (((y & 0xff000000) >> 24) ^ (y & 0x000000ff));
// reverse y = y ^ (y >> L); L = 18;
// const UPPER_18_BITS: u32 = u32::MAX << (M - 18);
// const LOWER_14_BITS: u32 = u32::MAX >> 18;
// let mut o = y & UPPER_18_BITS; // upper 18 bits are correct
// o |= ((o & UPPER_18_BITS) >> 18) ^ (y & LOWER_14_BITS); // all 32 bits are correct
// y = o;
// reverse y = y ^ ((y << T) & C);
// reverse y = y ^ ((y << S) & B);
// reverse y = y ^ (y >> U); U = 11;
// const UPPER_11_BITS: u32 = u32::MAX << (M - 11);
// const SECOND_11_BITS: u32 = UPPER_11_BITS >> 11;
// const LOWER_10_BITS: u32 = u32::MAX >> (M - 10);
// let mut o = y & UPPER_11_BITS; // upper 11 bits are correct
// o |= ((o & UPPER_11_BITS) >> 11) ^ (y & SECOND_11_BITS); // upper 22 bits are correct
// o |= ((o & SECOND_11_BITS) >> 11) ^ (y & LOWER_10_BITS); // all 32 bits are correct
// y = o;
y
}
@@ -412,13 +413,19 @@ pub fn challenge23() {
println!("{:#010x} -> {:#010x} -> {:#010x}", a, b, c);
/*
// Once you have "untemper" working, create a new MT19937 generator, tap it for 624 outputs,
let mut mt = mt19937::MT19937::new();
let seed: u32 = rand::thread_rng().gen::<u32>();
mt.seed(seed);
let outputs: Vec<u32> = (0..624).map(|_| mt.extract_number()).collect();
// untemper each of them to recreate the state of the generator,
let outputs = outputs.iter().map(|o| untemper(*o)).collect();
//and splice that state into a new instance of the MT19937 generator.
let mut new_mt = mt19937::MT19937::new();
new_mt.splice(outputs);
println!("{} {}", mt.extract_number(), new_mt.extract_number());
// and splice that state into a new instance of the MT19937 generator.
let mut spliced_mt = mt19937::MT19937::new();
spliced_mt.splice(outputs);
println!("{} {}", mt.extract_number(), spliced_mt.extract_number());
*/
println!("[xxxx] Challenge 23: wip");