如何获得已经散列的数据的真实价值？

Question

how to get the real value of data that has been hashed? is it possible that you can still get the real value of the data after you get the hashcode? or is there any code that can reverse the output.

String ida = new String(txtID.getText().toString());
    int idb = ida.hashCode();

    codeD.setText("result: " + ida );

i already get the hashcode of the txtID(the user that has been input), but now i want to get the the real value that has been hashed without calling the ida.

Answer 1

Short answer: no.

The long answer: A hash is meant to be a quick, one-way calculation to roughly identify some item. In Java, hash codes are usually used to putting something into a Map. The hash code is used to identify one Object from another when it is used as a key in the HashMap. It is not meant to store the data, only be different enough to prevent collisions. It is quite possible to have two objects that have the same hash.

Answer 2

As CodeChimp explained, what you are trying to do is not Hashing, but Encrypt/Decrypt . This example will help you do it: http://www.example-code.com/java/aes_dataStream.asp

If you are like me and enjoy reinventing the wheel, this could be fun to implement: http://en.wikipedia.org/wiki/Affine_cipher