Need to write java code for encryption and decryption of a file.

I need to write a java code for encrytpion and decryption of a file.

I need to encrypt a file using some predefined key and need to decrypt the same using that key.

Can someone guide me how can i do that or share the sample code for the same.

It is like read a file encrtpt the content using predefined key and write it back.

Now read the encrypted file decrypt it using the key and write it back.

"Beginning Cryptography with Java" by David Hook published by Wrox.

The standard Java API for en-/decryption is called JCE, and it's part of JSE. See the SecurityFaq for more material about it. An algorithm like AES or TripleDES would work.

above will be a good solution but if you really want to do that manually.....using your own keys and value then use hashmap..

but i think that should not be a good solution to use hashmap for encryption and decryption........

Can you guide me to some tutorials so that i can understand it better and can implement it.

Now the problem is that i need to encrypt the file at one system and want to decrypt at other system. So i need to have the same key for encryting and decrypting the data.

The algorithm i am using is DES encryption. Is there any way so that we give the key ourself instead of generating it randomly?

Don't use DES, it's too weak these days. Triple-DES (or "DESede", as it's called in JCE lingo) should be fine if you don't want to use AES.

The FAQ I pointed you to has an article that show how to use a pre-determined key instead of a random one with DES (in the JCE section); it works the same for Triple-DES.

pintoo saluja wrote:Now the problem is that i need to encrypt the file at one system and want to decrypt at other system. So i need to have the same key for encryting and decrypting the data.

The algorithm i am using is DES encryption. Is there any way so that we give the key ourself instead of generating it randomly?

Yes - but I'm not willing to just provide code. You need to spend a lot of time reading and the book I cited is a very good starting point.