RC2 decryption is not work for unique combination.

Hello evenryone,

In one of my web application i used the RC2 encryption / decryption for password. I use email id as key. Suddenly i found that it gives error for one unique password (12345678) and email id ([email protected]).
Application perform encryption successfully but when i try to decrypt my password again it gives error "System.Security.Cryptography.CryptographicException: Length of the data to decrypt is invalid.
   at System.Security.Cryptography.CryptoAPITransform.TransformFinalBlock(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount)
   at System.Security.Cryptography.CryptoStream.Read(Byte[] buffer, Int32 offset, Int32 count)
   at System.IO.StreamReader.ReadBuffer()
   at System.IO.StreamReader.ReadToEnd()"

If i do any changes in email id or password it works perfectly.

Is there is some problem with RC2 decryption for some values?

Please help me to fix this error.

Hey Laxmi,
I am interested in cryptography quite a bit so I would like to help you. But I am afraid the given information is not at all sufficient to help you. There are alot of questions such as what is your IV ? RC2 encryption default implementation use a 128 bit key and IV, but you are saying you are using email id as your key which is a variable length key.
This information tells me that this is a customized implementation of RC2 so there is no way of guessing what the problem is even. I have got similar error messages when there is a encoding mismatch of data but since your code is working fine and this is the only known exception, I would like to get more information.
Hopefully I can help you. =) Regards