feat: 实现多个挑战并改进测试

- 重写p1实现纯Rust的hex到base64转换
- 完成p13 ECB剪切粘贴攻击和破解脚本
- 实现p33 Diffie-Hellman密钥交换算法
- 修复p9的PKCS#7测试用例
- 在common库添加gen_random_key和pkcs7_unpadding函数
- 更新workspace依赖管理

common/src/lib.rs

@@ -1,6 +1,7 @@
 use std::collections::HashSet;
 
 use anyhow::{Result, anyhow};
+use rand::prelude::*;
 
 const SBOX: [u8; 256] = [
     0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
@@ -396,6 +397,22 @@ pub fn pkcs7_padding(data: &mut Vec<u8>, block_size: usize) {
     data.extend(vec![padding_length as u8; padding_length]);
 }
 
+pub fn pkcs7_unpadding(input: &[u8]) -> Result<Vec<u8>> {
+    if input.is_empty() {
+        return Err(anyhow!("Input cannot be empty"));
+    }
+    let padding_length = *input.last().unwrap();
+    if padding_length == 0 || padding_length > input.len() as u8 {
+        return Err(anyhow!("Invalid PKCS#7 padding"));
+    }
+    for &byte in input.iter().rev().take(padding_length as usize) {
+        if byte != padding_length {
+            return Err(anyhow!("Invalid PKCS#7 padding"));
+        }
+    }
+    Ok(input[..input.len() - padding_length as usize].to_vec())
+}
+
 pub fn is_ecb(cipher: &[u8]) -> bool {
     // Check if the input is a valid ECB encrypted data
     let mut seen_blocks = HashSet::new();
@@ -458,3 +475,10 @@ pub fn xor_with_key(input: &[u8], key: &[u8]) -> Result<Vec<u8>> {
         .map(|(&a, &b)| a ^ b)
         .collect())
 }
+
+pub fn gen_random_key() -> [u8; 16] {
+    let mut rng = rand::rng();
+    let mut key = [0u8; 16];
+    rng.fill(&mut key);
+    key
+}