decrypt not working fine using AES getting (Length of the data to decrypt is invalid) RSS

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  prince23

  Member

  18 Points

  91 Posts

  decrypt not working fine using AES getting (Length of the data to decrypt is invalid)

  Jan 06, 2013 03:21 AM|LINK

  Hi

  I am using the AES enscryption to decrypt the value
  In C# 4.0
  the code is written like this to decrypt the value
  encodedIdentityData contain the Encrypted value
  //string decodedIdentityData = Encoding.Unicode.GetString(MachineKey.Decode(encodedIdentityData, MachineKeyProtection.All))+",";
  i am having C#3.5 framework at my producation i cannot be updating it framework 4.0

  so i have rewritten the code to decrypt the value inc# 3.5 like this

  string strENC=Encrypt(encodedIdentityData);

          public static string Encrypt(string cookieValue)
          {
              return FormsAuthentication.Encrypt(new FormsAuthenticationTicket(1,
                                                                               string.Empty,
                                                                               DateTime.Now,
                                                                               DateTime.Now.AddMinutes(30),
                                                                               true,
                                                                               cookieValue));
          }

          public static string Decrypt(string encryptedTicket)
          {
              return FormsAuthentication.Decrypt(encryptedTicket).UserData;
          }

  when when i decrypt herein c# 3.5 i am getting an exception

  "Length of the data to decrypt is invalid."
     at System.Security.Cryptography.RijndaelManagedTransform.TransformFinalBlock(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount)
     at System.Security.Cryptography.CryptoStream.FlushFinalBlock()
     at System.Web.Configuration.MachineKeySection.EncryptOrDecryptData(Boolean fEncrypt, Byte[] buf, Byte[] modifier, Int32 start, Int32 length, IVType ivType, Boolean useValidationSymAlgo)
     at System.Web.Security.FormsAuthentication.Decrypt(String encryptedTicket)

   machine key what is used  to decrypt it
   
   <machineKey validationKey="0C4929BE691B98F63B94F2A7AA9CA5E1F430D6FFFA91FBEDAEC1D2DDAAC2127EB055DB857F5550ABC6EE8451D9AE3C13AFB78328C5BDE83249A94EA66400453B" decryptionKey="668B59FD4684EA13EACEAA833F2EEEABBECF2D066199F5C2D3652E224A82C265" validation="SHA1" decryption="AES" />

  any help on this would be great

  Thanks
  KUmar

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  BrockAllen

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  28082 Points

  4996 Posts

  MVP

  Re: decrypt not working fine using AES getting (Length of the data to decrypt is invalid)

  Jan 06, 2013 03:27 AM|LINK

  Write this code:

  string strENC=Encrypt(encodedIdentityData);
  string strPlain = Decrypt(strENC);

  and see if you have the same exception.

  Brock Allen | http://brockallen.com
  DevelopMentor | http://www.develop.com
  thinktecture | http://www.thinktecture.com/
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  prince23

  Member

  18 Points

  91 Posts

  Re: decrypt not working fine using AES getting (Length of the data to decrypt is invalid)

  Jan 07, 2013 06:42 AM|LINK

  Thanks for te reply

  Decrytedvalue=d239f325-0e7e-4dcb-8d37-86fb95814c80;c.kumar@gmail.com,1,.india.com,931

  EncryptedValue="FF8B1FEF0B3269D67D178CB56705EB5D9E7272FAA3E155AAB13C6DF4EE423522AFCFFF1BF6299BE989E96C906C24088FB3A9ABB7ADCAF15C12ED4801F70960DFA471710B2F137FA456C76504B97EB3B938F9C1D52B77D57F2F4811C16403544D31A60D69A25171A996DDD36C1F64A89B2B58D391F9B9DF0A212C280E6E069EB0D06EDA2DCC7972F2D8DAD1F667C52E103E223890335F6C770F6C0A0D3572778DD655BEF390B6C94C5BA931FFD8845458177A4219DB90768749B83FDA57CC89A4CB2D54AE7A7E5735C3AC67E2AFED26FFDB6AE92F5EEF67DCE46727EE796F438C8BD96EFA60C2EDB070408A99119A2E3E206967E2"

  when i pass  my  EncryptedValue to get decryted value it throws :

  
  exception:
  Length of the data to decrypt is invalid.

   

   

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  Angie xu - M...

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  20277 Points

  1726 Posts

  Microsoft

  Re: decrypt not working fine using AES getting (Length of the data to decrypt is invalid)

  Jan 11, 2013 05:39 AM|LINK

  Hi KUmar

  There are something wrong with the parameter in FormsAuthenticationTicket or FormsAuthentication.Decrypt method according to error message.

  you could refer the FormsAuthenticationTicket Class and FormsAuthentication.Decrypt method below, and check whether you use them properly,

  FormsAuthenticationTicket Class

  FormsAuthentication.Decrypt Method

  Understanding the Forms Authentication Ticket and Cookie http://support.microsoft.com/kb/910443

  hope it helps you,

  Kind regards

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  • Marked as answer by Angie xu - MSFT on Jan 14, 2013 12:13 AM