stage

problems/p11/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "p11"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+rand = "0.9.1"

problems/p11/src/main.rs

@@ -0,0 +1,49 @@
+use rand::{Rng, seq::IndexedRandom};
+
+fn gen_random_key() -> [u8; 16] {
+    let mut rng = rand::rng();
+    let mut key = [0u8; 16];
+    rng.fill(&mut key);
+    key
+}
+
+fn encryption_oracle(plaintext: &[u8]) -> Vec<u8> {
+    let key = gen_random_key();
+    let mut rng = rand::rng();
+    let enc_mode = rng.random_range(0..2); // 0 for ECB, 1 for CBC
+    let plaintext = plaintext.to_vec();
+    let random_prefix_len = rng.random_range(5..11);
+    let random_suffix_len = rng.random_range(5..11);
+    let mut random_padding = [0u8; 20];
+    rng.fill(&mut random_padding);
+    let random_prefix = random_padding[..random_prefix_len].to_vec();
+    let random_suffix = random_padding[random_padding.len() - random_suffix_len..].to_vec();
+
+    let mut data = Vec::new();
+    data.extend(random_prefix);
+    data.extend(plaintext);
+    data.extend(random_suffix);
+
+    pkcs7_padding(&mut data, 16); // in p9
+
+    if enc_mode == 0 {
+        // ECB mode in p7
+        ecb_encrypt(&data, &key)
+    } else {
+        // CBC mode in p10
+        let iv = [0u8; 16];
+        cbc_encrypt(&data, &key, &iv)
+    }
+    data
+}
+
+fn main() {
+    let plaintext = b"YELLOW SUBMARINE";
+    let encrypted_data = encryption_oracle(plaintext);
+    // in p8
+    if is_ecb(&encrypted_data) {
+        println!("ECB mode detected.");
+    } else {
+        println!("CBC mode detected.");
+    }
+}