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Finish challenge 23.

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This commit is contained in:
Felix Martin
2022-08-06 11:24:58 -04:00
parent b7ca276f72
commit 98ad4c7712
2 changed files with 62 additions and 41 deletions
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5
src/main.rs
View File

@@ -10,7 +10,7 @@ mod set2;
mod set3;
fn main() {
const RUN_ALL: bool = false;
const RUN_ALL: bool = true;
if RUN_ALL {
set1::challenge1();
set1::challenge2();
@@ -35,7 +35,8 @@ fn main() {
set3::challenge21();
set3::challenge22();
set3::challenge23();
set3::challenge24();
} else {
set3::challenge23();
set3::challenge24();
}
}

98
src/set3.rs
View File

@@ -304,7 +304,6 @@ pub fn challenge20() {
pub fn challenge21() {
// Implement the MT19937 Mersenne Twister RNG
let expected: Vec<u32> = vec![
0xD091BB5C, 0x22AE9EF6, 0xE7E1FAEE, 0xD5C31F79, 0x2082352C, 0xF807B7DF, 0xE9D30005,
0x3895AFE1, 0xA1E24BBA, 0x4EE4092B,
@@ -314,7 +313,7 @@ pub fn challenge21() {
for i in 0..expected.len() {
assert_eq!(mt.extract_number(), expected[i]);
}
println!("[okay] Challenge 21: Implemented MT19937");
println!("[okay] Challenge 21: implemented MT19937");
}
pub fn challenge22() {
@@ -355,64 +354,78 @@ pub fn challenge22() {
let found_seed = find_seed(rngout);
assert_eq!(seed, found_seed.unwrap());
println!("[done] Challenge 22: cracked MT19937 seed.");
println!("[okay] Challenge 22: cracked MT19937 seed");
}
pub fn challenge23() {
fn temper(x: u32) -> u32 {
fn _temper(x: u32) -> u32 {
const S: u32 = 7;
// const T: u32 = 15;
// const U: u32 = 11;
const T: u32 = 15;
const U: u32 = 11;
const B: u32 = 0x9D2C5680;
// const C: u32 = 0xEFC60000;
// const L: u32 = 18;
const C: u32 = 0xEFC60000;
const L: u32 = 18;
let mut y = x;
// y = y ^ (y >> U);
y = y ^ (y >> U);
y = y ^ ((y << S) & B);
// y = y ^ ((y << T) & C);
// y = y ^ (y >> L);
y = y ^ ((y << T) & C);
y = y ^ (y >> L);
y
}
fn untemper(x: u32) -> u32 {
//const S: u32 = 7;
//const T: u32 = 15;
//const B: u32 = 0x9D2C5680;
//const C: u32 = 0xEFC60000;
const M: u32 = 32;
const B: u32 = 0x9D2C5680;
const C: u32 = 0xEFC60000;
let mut y = x;
// 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;
const UPPER_18_BITS: u32 = u32::MAX << 14;
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 << T) & C); T = 15;
const LOWER_15_BITS: u32 = u32::MAX >> 17;
const MID_15_BITS: u32 = LOWER_15_BITS << 15;
const UPPER_2_BITS: u32 = u32::MAX << 30;
let mut o = y & LOWER_15_BITS; // lower 15 bits are correct
o |= ((o << 15) & C) ^ (y & MID_15_BITS); // lower 30 bits are correct
o |= (((o << 15) & C) & UPPER_2_BITS) ^ (y & UPPER_2_BITS); // all 32 bits are correct
y = o;
// reverse y = y ^ ((y << S) & B);
// reverse y = y ^ ((y << S) & B); S = 7
const LOWER_7_BITS: u32 = u32::MAX >> 25;
const SECOND_7_BITS: u32 = LOWER_7_BITS << 7;
const THIRD_7_BITS: u32 = SECOND_7_BITS << 7;
const FOURTH_7_BITS: u32 = THIRD_7_BITS << 7;
const UPPER_4_BITS: u32 = u32::MAX << 28;
let mut o = y & LOWER_7_BITS; // lower 7 bits are correct
o |= ((o << 7) & B) ^ (y & SECOND_7_BITS); // lower 14 bits are correct
o |= (((o << 7) & B) & THIRD_7_BITS) ^ (y & THIRD_7_BITS); // lower 21 bits are correct
o |= (((o << 7) & B) & FOURTH_7_BITS) ^ (y & FOURTH_7_BITS); // lower 28 bits are correct
o |= (((o << 7) & B) & UPPER_4_BITS) ^ (y & UPPER_4_BITS); // all 32 bits are correct
y = o;
// 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;
const UPPER_11_BITS: u32 = u32::MAX << 21;
const SECOND_11_BITS: u32 = UPPER_11_BITS >> 11;
const LOWER_10_BITS: u32 = u32::MAX >> 22;
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
}
let a: u32 = 0x12345678;
let b = temper(a);
let c = untemper(b);
println!("{:#010x} -> {:#010x} -> {:#010x}", a, b, c);
// untemper test code
// let a: u32 = 0x12345678;
// let b = _temper(a);
// let c = untemper(b);
// 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>();
@@ -425,8 +438,15 @@ pub fn challenge23() {
// 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");
// The new "spliced" generator should predict the values of the original.
for _ in 0..2000 {
assert_eq!(mt.extract_number(), spliced_mt.extract_number());
}
println!("[okay] Challenge 23: MT19937 RNG successfully cloned from output");
}
pub fn challenge24() {
println!("[xxxx] Challenge 24: xxx");
}