diff --git a/l5/.gitignore b/l5/.gitignore
new file mode 100644
index 0000000..f4f22b2
--- /dev/null
+++ b/l5/.gitignore
@@ -0,0 +1,3 @@
+*/target
+*.zip
+*.jpg
diff --git a/l5/librc4/Cargo.lock b/l5/librc4/Cargo.lock
new file mode 100644
index 0000000..354c633
--- /dev/null
+++ b/l5/librc4/Cargo.lock
@@ -0,0 +1,75 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "getrandom"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
+[[package]]
+name = "libc"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+
+[[package]]
+name = "librc4"
+version = "0.1.0"
+dependencies = [
+ "rand",
+]
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
diff --git a/l5/librc4/Cargo.toml b/l5/librc4/Cargo.toml
new file mode 100644
index 0000000..65cf27f
--- /dev/null
+++ b/l5/librc4/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "librc4"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+rand = "0.8.5"
diff --git a/l5/librc4/src/lib.rs b/l5/librc4/src/lib.rs
new file mode 100644
index 0000000..280b185
--- /dev/null
+++ b/l5/librc4/src/lib.rs
@@ -0,0 +1,38 @@
+fn ksa(key: &Vec<u8>) -> Vec<u8> {
+    let n = key.len();
+
+    let t = (0..=255)
+        .map(|i| key[i % n])
+        .collect::<Vec<_>>();
+
+    let mut s = (0..=255).collect::<Vec<_>>();
+
+    let mut j = 0;
+    for i in 0..256 {
+        j = (j + s[i] as usize + t[i] as usize) % 256;
+        s.swap(i, j);
+    }
+
+    s
+}
+
+fn prga(s: &mut Vec<u8>, data: &Vec<u8>) -> Vec<u8> {
+    let mut i = 0;
+    let mut j = 0;
+    let mut ciphertext = Vec::new();
+    for byte in data {
+        i = (i + 1) % 256;
+        j = (j + s[i] as usize) % 256;
+        s.swap(i, j);
+        let k = s[((s[i] as usize + s[j] as usize) % 256) as usize];
+        ciphertext.push(byte ^ k);
+    }
+    ciphertext
+}
+
+pub fn rc4(key: &Vec<u8>, data: &Vec<u8>) -> Vec<u8> {
+    let mut s = ksa(key);
+
+    prga(&mut s, data)
+}
+
diff --git a/l5/zad1/Cargo.lock b/l5/zad1/Cargo.lock
new file mode 100644
index 0000000..aa5cb7a
--- /dev/null
+++ b/l5/zad1/Cargo.lock
@@ -0,0 +1,90 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "getrandom"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
+[[package]]
+name = "hex"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
+
+[[package]]
+name = "libc"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+
+[[package]]
+name = "librc4"
+version = "0.1.0"
+dependencies = [
+ "rand",
+]
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
+[[package]]
+name = "zad1"
+version = "0.1.0"
+dependencies = [
+ "hex",
+ "librc4",
+ "rand",
+]
diff --git a/l5/zad1/Cargo.toml b/l5/zad1/Cargo.toml
new file mode 100644
index 0000000..b33d718
--- /dev/null
+++ b/l5/zad1/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "zad1"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+librc4 = { path = "../librc4" }
+rand = "0.8.5"
+hex = "0.4.3"
diff --git a/l5/zad1/src/main.rs b/l5/zad1/src/main.rs
new file mode 100644
index 0000000..f5d6e9c
--- /dev/null
+++ b/l5/zad1/src/main.rs
@@ -0,0 +1,43 @@
+#![feature(ascii_char)]
+
+use librc4::rc4;
+use rand::{thread_rng, Rng};
+
+fn test() {
+    let key = b"BigBrother".to_vec();
+    let cipher = hex::decode("62AEC4043041DB").unwrap();
+
+    let binding = rc4(&key, &cipher);
+    let data = binding.as_ascii().unwrap();
+
+    println!("data: {:?}", data);
+}
+
+fn main() {
+    test();
+    let k0 = b"".to_vec();
+    let k1 = b"".to_vec();
+    for i in 0..8192 {
+        print!("{i}: ");
+        let data = (0..1024)
+            .map(|_| thread_rng().gen())
+            .collect::<Vec<u8>>();
+        let c0 = rc4(&k0, &data);
+        let d0 = rc4(&k0, &c0);
+
+        let c1 = rc4(&k1, &data);
+        let d1 = rc4(&k1, &c1);
+
+        fn result(cond: bool) -> char {
+            match cond {
+                true => '👍',
+                false => '👎',
+            }
+        }
+
+        print!("k0: {}; ", result(data == d0));
+        print!("k1: {};", result(data == d1));
+
+        println!();
+    }
+}
diff --git a/l5/zad2/Cargo.lock b/l5/zad2/Cargo.lock
new file mode 100644
index 0000000..2495c4b
--- /dev/null
+++ b/l5/zad2/Cargo.lock
@@ -0,0 +1,82 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "getrandom"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.155"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+
+[[package]]
+name = "librc4"
+version = "0.1.0"
+dependencies = [
+ "rand",
+]
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
+[[package]]
+name = "zad2"
+version = "0.1.0"
+dependencies = [
+ "librc4",
+]
diff --git a/l5/zad2/Cargo.toml b/l5/zad2/Cargo.toml
new file mode 100644
index 0000000..ccf0596
--- /dev/null
+++ b/l5/zad2/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "zad2"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+librc4 = { path = "../librc4" }
diff --git a/l5/zad2/src/main.rs b/l5/zad2/src/main.rs
new file mode 100644
index 0000000..acea665
--- /dev/null
+++ b/l5/zad2/src/main.rs
@@ -0,0 +1,40 @@
+use librc4::rc4;
+
+fn check_same_key(c0: &Vec<u8>, c1: &Vec<u8>) -> bool {
+    for i in 0..c0.len().min(c1.len()) {
+        if c0[i] ^ c1[i] >= 0x80 {
+            return false;
+        }
+    }
+
+    true
+}
+
+fn main() {
+    let k0 = b"some random key".to_vec();
+    let k1 = b"a different key".to_vec();
+
+    let d0 = b"02831923821370983210".to_vec();
+    let d1 = b"9483012137839109312903".to_vec();
+
+    let c0 = rc4(&k0, &d0);
+    let c1 = rc4(&k1, &d1);
+
+    fn result(cond: bool) -> &'static str {
+        match cond {
+            true => "the keys were the same!",
+            false => "the keys were different!",
+        }
+    }
+
+    println!("keys should be different");
+    println!("result: {}", result(check_same_key(&c0, &c1)));
+
+    let key = b"these keys are identical".to_vec();
+
+    let c0 = rc4(&key, &d0);
+    let c1 = rc4(&key, &d1);
+
+    println!("keys should be the same");
+    println!("result: {}", result(check_same_key(&c0, &c1)));
+}
diff --git a/l5/zad3/Cargo.lock b/l5/zad3/Cargo.lock
new file mode 100644
index 0000000..8753f8c
--- /dev/null
+++ b/l5/zad3/Cargo.lock
@@ -0,0 +1,109 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "either"
+version = "1.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3dca9240753cf90908d7e4aac30f630662b02aebaa1b58a3cadabdb23385b58b"
+
+[[package]]
+name = "getrandom"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
+[[package]]
+name = "itertools"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "413ee7dfc52ee1a4949ceeb7dbc8a33f2d6c088194d9f922fb8318faf1f01186"
+dependencies = [
+ "either",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.155"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+
+[[package]]
+name = "librc4"
+version = "0.1.0"
+dependencies = [
+ "rand",
+]
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "rand_pcg"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59cad018caf63deb318e5a4586d99a24424a364f40f1e5778c29aca23f4fc73e"
+dependencies = [
+ "rand_core",
+]
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
+[[package]]
+name = "zad3"
+version = "0.1.0"
+dependencies = [
+ "itertools",
+ "librc4",
+ "rand",
+ "rand_pcg",
+]
diff --git a/l5/zad3/Cargo.toml b/l5/zad3/Cargo.toml
new file mode 100644
index 0000000..5ea455e
--- /dev/null
+++ b/l5/zad3/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "zad3"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+librc4 = { path = "../librc4" }
+rand = "0.8.5"
+rand_pcg = "0.3.1"
+itertools = "0.13.0"
diff --git a/l5/zad3/links b/l5/zad3/links
new file mode 100644
index 0000000..c8b381d
--- /dev/null
+++ b/l5/zad3/links
@@ -0,0 +1 @@
+https://bankoweabc.pl/2021/05/05/cyfry-w-numerze-rachunku-bankowego/
diff --git a/l5/zad3/src/main.rs b/l5/zad3/src/main.rs
new file mode 100644
index 0000000..a2adc45
--- /dev/null
+++ b/l5/zad3/src/main.rs
@@ -0,0 +1,66 @@
+use itertools::Itertools;
+use librc4::rc4;
+use rand::{Rng, SeedableRng};
+use rand_pcg::Pcg64;
+
+fn main() {
+    let bank_numbers = gen_bank_numbers(10);
+    let key = b"amazingkeysolong".to_vec();
+    let cryptograms = &bank_numbers.iter()
+        .map(|bank_number| rc4(&key, &bank_number.as_bytes().to_vec()))
+        .collect::<Vec<_>>();
+
+    for (c0, c1) in cryptograms.iter().tuple_combinations() {
+        let xored: Vec<u8> = c0.iter()
+            .zip(c1.iter())
+            .map(|(i0, i1)| i0 ^ i1)
+            .collect();
+
+        println!();
+        println!("c0: {:?}", c0);
+        println!("c1: {:?}", c1);
+        println!("xored: {:?}", xored); 
+        println!();
+    }
+}
+
+fn gen_bank_numbers(q: usize) -> Vec<String> {
+    let mut bank_numbers: Vec<String> = Vec::new();
+    let routing_numbers: [[u8; 8]; 5] = [
+        [1, 0, 1, 0, 0, 0, 0, 0], // NBP
+        [1, 0, 2, 0, 1, 0, 9, 7], // PKO BP, oddział 8 w WWA
+        [1, 0, 5, 0, 1, 9, 2, 4], // ING, oddział pruszków ul Ołówkowa 1d
+        [1, 2, 4, 0, 5, 4, 8, 4], // Pekao, oddział w Gdańsku ul Franciszka Rakoczego 17
+        [1, 7, 5, 0, 1, 2, 8, 1], // BNP Paribas, oddział w Poznaniu al. Solidarności 36
+    ]; 
+    let mut rng = Pcg64::seed_from_u64(2137);
+    for nr in routing_numbers {
+        for _ in 0..q {
+            let mut bank_number = String::new();
+            let mut client_number = [0u8; 16];
+            for i in 0..16 {
+                client_number[i] = rng.gen_range(0..10);
+            }
+            let mut tmp: u128 = 252100;
+            for i in 0..8 {
+                tmp += nr[i] as u128 * 10u128.pow((7 - i + 21) as u32);
+            }
+            for i in 0..16 {
+                tmp += client_number[i] as u128 * 10u128.pow((15 - i + 5) as u32);
+            }
+
+            tmp = tmp % 97;
+            tmp = 98 - tmp;
+
+            bank_number.push_str(format!("{:02}", tmp).as_str());
+            for i in 0..8 {
+                bank_number.push_str(nr[i].to_string().as_str());
+            }
+            for i in 0..16 {
+                bank_number.push_str(client_number[i].to_string().as_str());
+            }
+            bank_numbers.push(bank_number);
+        }
+    }
+    bank_numbers
+}