feat: finish p31

Cargo.toml

@@ -16,3 +16,7 @@ num-traits = "0.2"
 once_cell = "1.21"
 rayon = "1.11.0"
 crypto-bigint = "0.6"
+axum = "0.8"
+tokio = { version = "1", features = ["full"] }
+serde = { version = "1", features = ["derive"] }
+reqwest = "0.12"

problems/p31/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "p31"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+reqwest = { workspace = true }
+tokio = { workspace = true }
+axum = { workspace = true }
+serde = { workspace = true }
+common = { path = "../../common/" }
+hex = { workspace = true }
+rand = { workspace = true }
+anyhow = { workspace = true }

problems/p31/src/main.rs

@@ -0,0 +1,134 @@
+use std::time::{Duration, Instant};
+
+use common::sha1;
+
+use anyhow::Result;
+use axum::{Router, extract::Query, http::StatusCode, routing::get};
+use rand::Rng;
+use serde::Deserialize;
+use std::sync::LazyLock;
+use tokio::time::sleep;
+
+static HMAC_KEY: LazyLock<[u8; 20]> = LazyLock::new(|| {
+    // 生成随机密钥
+    let mut rng = rand::rng();
+    let key: [u8; 20] = rng.random();
+    key
+});
+
+#[derive(Deserialize)]
+struct Params {
+    file: String,
+    signature: String,
+}
+
+async fn verify_handler(Query(params): Query<Params>) -> StatusCode {
+    let my_signature = hmac_sha1(&*HMAC_KEY, params.file.as_bytes());
+
+    let provided_signature = match hex::decode(&params.signature) {
+        Ok(bytes) => bytes,
+        Err(e) => {
+            eprintln!("Hex decode error: {:?}", e);
+            return StatusCode::BAD_REQUEST;
+        }
+    };
+
+    match insecure_compare(&my_signature, &provided_signature).await {
+        true => StatusCode::OK,
+        false => StatusCode::INTERNAL_SERVER_ERROR,
+    }
+}
+
+async fn insecure_compare(a: &[u8], b: &[u8]) -> bool {
+    if a.len() != b.len() {
+        return false;
+    }
+    for i in 0..a.len() {
+        if a[i] != b[i] {
+            return false;
+        }
+        sleep(Duration::from_millis(50)).await;
+    }
+    true
+}
+
+fn hmac_sha1(key: &[u8], message: &[u8]) -> [u8; 20] {
+    let mut key = match key.len() {
+        0..=64 => key.to_vec(),
+        _ => sha1(key).to_vec(),
+    };
+    key.extend(vec![0; 64 - key.len()]);
+    let mut part_1 = key.iter().map(|x| x ^ 0x5c).collect::<Vec<u8>>();
+    let mut part_2_input = key.iter().map(|x| x ^ 0x36).collect::<Vec<u8>>();
+    part_2_input.extend(message);
+    let part_2 = sha1(&part_2_input);
+    part_1.extend(part_2);
+    sha1(&part_1)
+}
+#[test]
+fn test_hmac_sha1() {
+    let output = hmac_sha1("123".as_bytes(), "helloworld".as_bytes());
+    let output = hex::encode(output);
+    let correct = "8849fb5557760d35f19e2100aa250bfb97152bd9";
+    assert_eq!(output, correct);
+}
+
+async fn start_attack() -> Result<()> {
+    let mut signature = vec![0u8; 20]; // 用可变字节数组
+    let mut pos = 0; // 当前爆破位置
+
+    while pos < 20 {
+        let mut max_time = Duration::from_millis(0);
+        let mut best_byte = 0u8;
+
+        // 尝试当前位置的所有可能字节值
+        for byte in 0x00..=0xff {
+            signature[pos] = byte;
+            let url = format!(
+                "http://localhost:3000/verify?file={}&signature={}",
+                "helloworld",
+                hex::encode(&signature)
+            );
+
+            let start = Instant::now();
+            let status = reqwest::get(&url).await?.status();
+            let elapsed = start.elapsed();
+
+            if status == StatusCode::OK {
+                println!("✓ 找到完整签名: {}", hex::encode(&signature));
+                return Ok(());
+            }
+
+            // 记录耗时最长的字节
+            if elapsed > max_time {
+                max_time = elapsed;
+                best_byte = byte;
+            }
+        }
+
+        signature[pos] = best_byte;
+        println!(
+            "位置 {} 确定为: {:02x}, 耗时: {:?}",
+            pos, best_byte, max_time
+        );
+        pos += 1;
+    }
+
+    Ok(())
+}
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let app = Router::new().route("/verify", get(verify_handler));
+
+    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000").await?;
+
+    dbg!(hex::encode(*HMAC_KEY));
+
+    // 后台启动服务器
+    tokio::spawn(async move {
+        axum::serve(listener, app).await.unwrap();
+    });
+    start_attack().await?;
+    Ok(())
+}