CryptographicException - 错误数据

时间:2012-11-12 12:29:32

标签: c# winforms cryptography

我开发了一个使用加密的WinForms解决方案。

我遇到的一个问题是处理空密码(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(如果它为空)并将其值设置为空字符串。

然而,我得到例外: CryptoGraphic Exception(错误数据)。

这是堆栈跟踪:

at 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)    at xxx.Security.Cryptography.Decrypt(String cipherString,Boolean useHashing)in C:\ xxxx \ xxxx \ xxxx \ xxxx \ xxxx \ xxxx \ Cryptography.cs:第82行

以下是该类的源代码:

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(""));
            }
        }
        }
    }
}

所以问题在于Decrypt方法。有什么线索吗?

P.S。是的,我知道代码并不理想。这堂课不是我写的,我只是想用它。谢谢你的改进建议,我一定会让他们满意。

1 个答案:

答案 0 :(得分:2)

如果你真的想要允许空密码,请确保你的特殊情况为null以及空字符串。

所以改变

if (toEncrypt == "")

if (string.IsNullOrEmpty(toEncrypt))

如果toEncrypt为空或空,则返回null。

同时更改

if (cipherString == "")

if (string.IsNullOrWhiteSpace(cipherString))

如果'cipherString'为null或空格,则返回空字符串。

NB - 上面的CodesInChaos的评论非常正确。这段代码有一定的气味。他给出了很好的建议。