diff --git a/codes/md5-dist/.gitignore b/codes/md5-dist/.gitignore
new file mode 100644
index 00000000..ea8c4bf7
--- /dev/null
+++ b/codes/md5-dist/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/codes/md5-dist/Cargo.lock b/codes/md5-dist/Cargo.lock
new file mode 100644
index 00000000..cbc391be
--- /dev/null
+++ b/codes/md5-dist/Cargo.lock
@@ -0,0 +1,70 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "block-buffer"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0bf7fe51849ea569fd452f37822f606a5cabb684dc918707a0193fd4664ff324"
+dependencies = [
+ "generic-array",
+]
+
+[[package]]
+name = "crypto-common"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57952ca27b5e3606ff4dd79b0020231aaf9d6aa76dc05fd30137538c50bd3ce8"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
+[[package]]
+name = "digest"
+version = "0.10.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2fb860ca6fafa5552fb6d0e816a69c8e49f0908bf524e30a90d97c85892d506"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+]
+
+[[package]]
+name = "generic-array"
+version = "0.14.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd48d33ec7f05fbfa152300fdad764757cbded343c1aa1cff2fbaf4134851803"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
+[[package]]
+name = "md-5"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "658646b21e0b72f7866c7038ab086d3d5e1cd6271f060fd37defb241949d0582"
+dependencies = [
+ "digest",
+]
+
+[[package]]
+name = "md5-dist"
+version = "0.1.0"
+dependencies = [
+ "md-5",
+]
+
+[[package]]
+name = "typenum"
+version = "1.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dcf81ac59edc17cc8697ff311e8f5ef2d99fcbd9817b34cec66f90b6c3dfd987"
+
+[[package]]
+name = "version_check"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
diff --git a/codes/md5-dist/Cargo.toml b/codes/md5-dist/Cargo.toml
new file mode 100644
index 00000000..b003966e
--- /dev/null
+++ b/codes/md5-dist/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "md5-dist"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+md-5 = "0.10.1"
diff --git a/codes/md5-dist/countmap.txt b/codes/md5-dist/countmap.txt
new file mode 100644
index 00000000..b78b1120
--- /dev/null
+++ b/codes/md5-dist/countmap.txt
@@ -0,0 +1,256 @@
+00: 16775418
+01: 16784471
+02: 16782205
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diff --git a/codes/md5-dist/src/main.rs b/codes/md5-dist/src/main.rs
new file mode 100644
index 00000000..987c91e3
--- /dev/null
+++ b/codes/md5-dist/src/main.rs
@@ -0,0 +1,28 @@
+use md5::{Digest, Md5};
+use std::{
+    collections::HashMap,
+    fs::File,
+    io::{BufWriter, Write},
+};
+
+fn main() -> std::io::Result<()> {
+    let mut map = HashMap::new();
+    for i in 0u32..=std::u32::MAX {
+        let mut hasher = Md5::new();
+        hasher.update(i.to_le_bytes());
+        let out = hasher.finalize();
+        let key = out[out.len() - 1];
+        *map.entry(key).or_insert(0) += 1;
+        if i % 100_000 == 0 {
+            println!("{i}");
+        }
+    }
+    let mut count_list = map.into_iter().collect::<Vec<_>>();
+    count_list.sort();
+    let file = File::create("./countmap.txt")?;
+    let mut writer = BufWriter::new(file);
+    for (k, v) in count_list {
+        writeln!(writer, "{:02x}: {}", k, v)?;
+    }
+    Ok(())
+}
diff --git a/codes/md5-dist/src/main.rs_all_ips_bak b/codes/md5-dist/src/main.rs_all_ips_bak
new file mode 100644
index 00000000..cee15e4f
--- /dev/null
+++ b/codes/md5-dist/src/main.rs_all_ips_bak
@@ -0,0 +1,21 @@
+use md5::{Digest, Md5};
+use std::{
+    fs::File,
+    io::{BufWriter, Write},
+};
+
+fn main() -> std::io::Result<()> {
+    let file = File::create("./hashes.txt")?;
+    let mut writer = BufWriter::new(file);
+    for i in 0u32..=std::u32::MAX {
+        let mut hasher = Md5::new();
+        // let mut out = [0; 16];
+        hasher.update(i.to_le_bytes());
+        let out = hasher.finalize();
+        writeln!(writer, "{:02x}", out[out.len() - 1])?;
+        if i % 100_000 == 0 {
+            println!("{i}");
+        }
+    }
+    Ok(())
+}
diff --git a/codes/md5dist-plot/.gitignore b/codes/md5dist-plot/.gitignore
new file mode 100644
index 00000000..1d17dae1
--- /dev/null
+++ b/codes/md5dist-plot/.gitignore
@@ -0,0 +1 @@
+.venv
diff --git a/codes/md5dist-plot/countmap.txt b/codes/md5dist-plot/countmap.txt
new file mode 100644
index 00000000..b78b1120
--- /dev/null
+++ b/codes/md5dist-plot/countmap.txt
@@ -0,0 +1,256 @@
+00: 16775418
+01: 16784471
+02: 16782205
+03: 16777355
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diff --git a/codes/md5dist-plot/dist.png b/codes/md5dist-plot/dist.png
new file mode 100644
index 00000000..87ac864e
Binary files /dev/null and b/codes/md5dist-plot/dist.png differ
diff --git a/codes/md5dist-plot/dist.py b/codes/md5dist-plot/dist.py
new file mode 100755
index 00000000..2f48e45b
--- /dev/null
+++ b/codes/md5dist-plot/dist.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python3
+
+from collections import defaultdict
+
+import matplotlib.pyplot as plt
+
+def main():
+    with open('./countmap.txt', 'r') as f:
+        countmap = {}
+        keys = []
+        values = []
+        for line in f:
+            split = line.split(': ')
+            prefix = split[0].strip()
+            key = int(prefix, 16)
+            value = int(split[1].strip())
+            countmap[key] = value
+            keys.append(key)
+            values.append(value)
+
+        plt.bar(keys, values)
+        plt.title('Distribution of lowest byte of hashed IP addresses')
+        plt.savefig('dist.png')
+        plt.show()
+
+    # with open('./hashes.txt', 'r') as f:
+    #     # countmap = defaultdict(lambda: 0)
+    #     ints = set()
+    #     data = []
+    #     for line in f.readlines():
+    #         # line = line.strip()
+    #         # prefix = line[len(line) - 2:]
+    #         prefix = line.strip()
+    #         ints.add(prefix)
+    #         # countmap[prefix] = countmap[prefix] + 1
+    #         data.append(int(prefix, 16))
+
+    #     plt.hist(data, bins=len(ints))
+    #     plt.title('Distribution of lowest byte of hashed IP addresses')
+        # plt.savefig('dist.png')
+    #     plt.show()
+    #     # print(countmap)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/codes/md5dist-plot/requirements.txt b/codes/md5dist-plot/requirements.txt
new file mode 100644
index 00000000..fec370b7
--- /dev/null
+++ b/codes/md5dist-plot/requirements.txt
@@ -0,0 +1 @@
+matplotlib==3.5.1