fix(decrypt): 修复解密过程中的IV生成逻辑

src/encryption/spiral.rs

@@ -45,10 +45,16 @@ pub fn decrypt(data: String) -> Result<String, SpiralCipherError> {
     let data = data[1..].to_string();
     let key_seed = data[0..20].to_string();
     let key = gen_key(&key_seed);
-    let iv: [u8; 16] = key[0..16].try_into().unwrap();
-    let decryptor = AesDecryptor::new(&key.into(), &iv.into());
+
     let encrypted_data = crate::serialize::from_base64_str(&data[20..])
         .map_err(|_| SpiralCipherError::CorruptedCipherData)?;
+
+    // 使用key的前16字节作为IV（与Go版本PrefixIVGenerator对应）
+    let iv: [u8; 16] = key[0..16]
+        .try_into()
+        .map_err(|_| SpiralCipherError::CorruptedCipherData)?;
+
+    let decryptor = AesDecryptor::new(&key.into(), &iv.into());
     let decrypted_data = decryptor
         .decrypt_padded_vec_mut::<cipher::block_padding::Pkcs7>(encrypted_data.as_slice())
         .map_err(|e| {