1

我开发了一个使用加密的 WinForms 解决方案。

我遇到的问题之一是处理空密码（例如没有设置密码）。显然，空字符串会导致加密异常，所以我试图阻止加密/解密字符串，如果它是空的，并将它的值设置为空字符串。

但是，我得到了异常： CryptoGraphic Exception (Bad Data)。

这是堆栈跟踪：

在 System.Security.Cryptography.CryptographicException.ThrowCryptographicException(Int32 hr) 在 System.Security.Cryptography.Utils._DecryptData(SafeKeyHandle hKey, Byte[] data, Int32 ib, Int32 cb, Byte[]& outputBuffer, Int32 outputOffset, PaddingMode PaddingMode , Boolean fDone) 在 System.Security.Cryptography.CryptoAPITransform.TransformFinalBlock(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount) 在 xxx.Security.Cryptography.Decrypt(String cipherString, Boolean useHashing) 在 C:\xxxx\xxxx\xxxx \xxxx\xxxx\xxxx\Cryptography.cs：第 82 行

这是该类的源代码：

using System;
using System.Security.Cryptography;
using System.Text;

namespace xxx
{
  public class Cryptography
  {
    private const string key = "xxxx";

    public static string Encrypt(string toEncrypt, bool useHashing)
    {
        if (toEncrypt == "")
        {
            string result = System.Convert.ToBase64String(Encoding.UTF8.GetBytes(toEncrypt));
            return result;
        }
        else
        {
            try
            {
                byte[] keyArray;
                byte[] toEncryptArray = Encoding.UTF8.GetBytes(toEncrypt);

                //If hashing use get hashcode regards to your key
                if (useHashing)
                {
                    MD5CryptoServiceProvider md5CryptoServiceProvider = new MD5CryptoServiceProvider();
                    keyArray = md5CryptoServiceProvider.ComputeHash(Encoding.UTF8.GetBytes(key));
                    md5CryptoServiceProvider.Clear();
                }
                else
                    keyArray = Encoding.UTF8.GetBytes(key);

                TripleDESCryptoServiceProvider tripleDesCryptoServiceProvider = new TripleDESCryptoServiceProvider();
                //set the secret key for the tripleDES algorithm
                tripleDesCryptoServiceProvider.Key = keyArray;
                //mode of operation. there are other 4 modes.
                //We choose ECB(Electronic code Book)
                tripleDesCryptoServiceProvider.Mode = CipherMode.ECB;
                //padding mode(if any extra byte added)

                tripleDesCryptoServiceProvider.Padding = PaddingMode.PKCS7;

                ICryptoTransform cTransform = tripleDesCryptoServiceProvider.CreateEncryptor();
                //transform the specified region of bytes array to resultArray
                byte[] resultArray =
                  cTransform.TransformFinalBlock(toEncryptArray, 0,
                  toEncryptArray.Length);
                //Release resources held by TripleDes Encryptor
                tripleDesCryptoServiceProvider.Clear();
                //Return the encrypted data into unreadable string format
                return Convert.ToBase64String(resultArray, 0, resultArray.Length);
            }
            catch (Exception)
            {
                string result = System.Convert.ToBase64String(Encoding.UTF8.GetBytes(toEncrypt));
                return result;
            }
        }
    }


    public static string Decrypt(string cipherString, bool useHashing)
    {
        if (cipherString == "")
        {
            UTF8Encoding utf8 = new UTF8Encoding();
            return Encoding.UTF8.GetString(utf8.GetBytes(""));
        }
        else
        {
            try
            {
                byte[] keyArray;
                //get the byte code of the string

                byte[] toEncryptArray = Convert.FromBase64String(cipherString);


                if (useHashing)
                {
                    //if hashing was used get the hash code with regards to your key
                    MD5CryptoServiceProvider md5CryptoServiceProvider = new MD5CryptoServiceProvider();
                    keyArray = md5CryptoServiceProvider.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
                    //release any resource held by the MD5CryptoServiceProvider

                    md5CryptoServiceProvider.Clear();
                }
                else
                {
                    //if hashing was not implemented get the byte code of the key
                    keyArray = UTF8Encoding.UTF8.GetBytes(key);
                }

                TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
                //set the secret key for the tripleDES algorithm
                tdes.Key = keyArray;
                //mode of operation. there are other 4 modes. 
                //We choose ECB(Electronic code Book)

                tdes.Mode = CipherMode.ECB;
                //padding mode(if any extra byte added)
                tdes.Padding = PaddingMode.PKCS7;

                ICryptoTransform cTransform = tdes.CreateDecryptor();
                byte[] resultArray = cTransform.TransformFinalBlock(
                                     toEncryptArray, 0, toEncryptArray.Length);
                //Release resources held by TripleDes Encryptor                
                tdes.Clear();
                //return the Clear decrypted TEXT
                return Encoding.UTF8.GetString(resultArray);
            }
            catch (Exception)
            {
                UTF8Encoding utf8 = new UTF8Encoding();
                return Encoding.UTF8.GetString(utf8.GetBytes(""));
            }
        }
        }
    }
}

所以问题出在解密方法上。请问有什么线索吗？

PS 是的，我知道代码并不理想。这门课不是我写的，我只是想用它。感谢您提出改进建议，我一定会考虑它们。

4

1 回答 1

2

如果您真的想允许空密码，请确保您使用特殊情况的 null 以及空字符串。

所以改变

if (toEncrypt == "")

至

if (string.IsNullOrEmpty(toEncrypt))

如果toEncrypt为 null 或为空，则返回 null。

也改变

if (cipherString == "")

至

if (string.IsNullOrWhiteSpace(cipherString))

如果 'cipherString' 为空或空格，则返回一个空字符串。

注意 - 上面 CodesInChaos 的评论是非常正确的。这段代码有一定的味道。他给出了很好的建议。

于 2012-11-12T12:32:04.220 回答