Question

My encryption and decryption is running good without using a file. But I have to store the encrypted data in a file and transfer it to a peer system, where I have to read the file and decrypt it.
The problem I face is, a single unicode on encryption gives me a set of unicodes(thats my cipher) like this.

                                  ☺ ╪iß 

When I store these cipher in a file, the decryption will be done for each of the unicodes separately. But the decrption should be done for the respective set of unicodes to get back my plaintext. How should I store them in a file? How could I select the corresponding unicodes on decryption to get back my plaintext? I’m using the keys of size 1024 bits.

Answer 1

Encryption algorithms don’t work on unicode characters. They work on binary data: byte arrays.

If you need to encrypt unicode text (a String, for example), then choose a non lossy byte encoding for the String (like UTF-8, for example), transform the String to a byte array (String.getBytes("UTF-8")), encrypt the byte array, and write the resulting byte array to the file.

When decrypting, read the file as a byte array, decrypt this byte array (which gives another byte array), and recreate a String from this byte array using the same character encoding: new String(plainTextBytes, "UTF-8").