My question is simple I am expecting encryption algorithm,
I need to encrypt a original data(text etc.) that encrypted data size should be same size of original data size? Share your idea kindly?
Example: Original data is "test" (so length of text is 4) the expected encrypted data should be like this "etst" (so length is 4).
This is not always possible, especially with short amounts of data. I am pretty sure that all the standard algorithms work on "blocks", which are usually the length of the key. So unless you go with a really weak key, or use something weak like substitution cipher or caesar cipher your encrypted data could end up a little longer than the original.
Actually, according to this page you can use a stream cipher and get encrypted text that is the same size as the input. The example given is RC4.