feat: finish p16

problems/p16/Cargo.toml

@@ -4,3 +4,5 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+common = { path = "../../common/" }
+rand = { workspace = true }

problems/p16/src/main.rs

@@ -1,3 +1,48 @@
-fn main() {
-    println!("Hello, world!");
+use common::{aes_cbc_dec, aes_cbc_enc, pkcs7_padding, pkcs7_unpadding};
+use rand::{Rng, rng};
+fn append_and_enc(input: String, key: &[u8; 16]) -> Vec<u8> {
+    let input = input.replace(";", "\\;").replace("=", "\\=");
+    let prefix = "comment1=cooking%20MCs;userdata=".to_string();
+    let suffix = ";comment2=%20like%20a%20pound%20of%20bacon";
+    // println!("{}, {}", prefix.len(), suffix.len()); // 32, 42
+
+    let mut buffer = prefix + &input + suffix;
+    let input = unsafe { buffer.as_mut_vec() };
+    pkcs7_padding(input, 16);
+
+    let iv = [0u8; 16];
+
+    aes_cbc_enc(input, key, &iv).unwrap()
+}
+
+fn verify(cipher: &[u8], key: &[u8; 16]) -> bool {
+    let iv = [0u8; 16];
+    let plaintext = aes_cbc_dec(cipher, key, &iv).unwrap();
+    let plaintext = pkcs7_unpadding(&plaintext).unwrap();
+    let plaintext = String::from_utf8_lossy(&plaintext);
+    println!("{}", plaintext);
+    plaintext.contains(";admin=true;")
+}
+
+fn main() {
+    let mut rng = rng();
+    let key: [u8; 16] = rng.random();
+
+    // 构造输入，第一个块用于反转破坏
+    let input = "A".repeat(16) + &"A".repeat(5) + "XadminXtrue";
+    let mut cipher = append_and_enc(input, &key);
+
+    // 计算目标位置：prefix(32) + padding(16) + target_start = 48 + 1 = 49
+    // 目标在第4块，需要修改第3块
+    let block_to_modify = 2 * 16; // 第3块起始位置
+
+    // 修改密文来翻转目标位
+    cipher[block_to_modify + 5] ^= b'X' ^ b';'; // X -> ;
+    cipher[block_to_modify + 11] ^= b'X' ^ b'='; // X -> =
+
+    if verify(&cipher, &key) {
+        println!("Attack successful!");
+    } else {
+        println!("Attack failed");
+    }
 }