diff --git a/src/day22.rs b/src/day22.rs
new file mode 100644
index 0000000..043f0d4
--- /dev/null
+++ b/src/day22.rs
@@ -0,0 +1,62 @@
+use std::{fs::read_to_string, ops::BitXor};
+
+pub fn day_main() {
+    let input = read_to_string("input/day22.txt").unwrap();
+    let input = input.trim();
+    println!(" part1: {}", part1(input));
+    println!(" part2: {}", part2(input));
+}
+
+type RiddleResult = i64;
+
+fn part1(input: &str) -> RiddleResult {
+    input.lines().map(|is| solution(is.parse().unwrap())).sum()
+}
+
+fn solution(initial_secret: i64) -> i64 {
+    let mut secret = initial_secret;
+    for _ in 0..2000 {
+        secret = prune(mix(secret * 64, secret));
+        secret = prune(mix(secret / 32, secret));
+        secret = prune(mix(secret * 2048, secret))
+    }
+    secret
+}
+
+fn mix(value: i64, secret: i64) -> i64 {
+    value.bitxor(secret)
+}
+
+fn prune(value: i64) -> i64 {
+    value % 16777216
+}
+
+fn part2(_input: &str) -> RiddleResult {
+    0
+}
+
+#[cfg(test)]
+mod test {
+    use super::{part1, part2};
+
+    const TEST_INPUT: &str = r"";
+
+    #[test]
+    fn test1() {
+        assert_eq!(
+            part1(
+                "1
+10
+100
+2024
+"
+            ),
+            37327623
+        );
+    }
+
+    #[test]
+    fn test2() {
+        assert_eq!(part2(TEST_INPUT), 0);
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 702ea95..101b4ad 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -16,5 +16,6 @@ pub mod day15;
 pub mod day16;
 pub mod day17;
 pub mod day19;
+pub mod day22;
 // PLACEHOLDER
 pub mod utils;
diff --git a/src/main.rs b/src/main.rs
index abeb103..da516eb 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -23,6 +23,7 @@ fn main() {
         (16, day16::day_main),
         (17, day17::day_main),
         (19, day19::day_main),
+        (22, day22::day_main),
         // PLACEHOLDER
     ]);
     let day: Option<u8> = args().nth(1).and_then(|a| a.parse().ok());