source: trunk/src/org/expeditee/auth/EncryptedProfileExpWriter.java@ 1202

package org.expeditee.auth;

import java.io.IOException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.Base64;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import org.expeditee.io.ExpWriter;
import org.expeditee.items.Text;
import org.expeditee.settings.auth.secrets.KeyList;
import org.ngikm.cryptography.CryptographyConstants;

public class EncryptedProfileExpWriter extends ExpWriter implements CryptographyConstants {
        private SecretKey personalKey;
        private static final String nl = "\n";
        
        public EncryptedProfileExpWriter() throws IOException {
                // obtain personal key
                final Text text = KeyList.PersonalKey.get();
                final byte[] keyBytes = Base64.getDecoder().decode(text.getData().get(0));
                personalKey = new SecretKeySpec(keyBytes, SymmetricAlgorithm);          
        }

        @Override
        protected void preOutputFrame() {
                try {
                        final String line = EncryptedExpReader.ENCRYPTED_EXP_FLAG + nl;
                        _writer.write(line);
                        _stringWriter.append(line);
                } catch (final IOException e) { 
                        e.printStackTrace();
                }
        }
        
        @Override
        protected void writeLine(String line) throws IOException {
                // do not write empty lines
                if (line == null) { return; }
                
                // prepare line to write out
                final byte[] encrypted = EncryptSymmetric(line.getBytes(), personalKey);
                final String toWrite = Base64.getEncoder().encodeToString(encrypted) + nl;
                
                // output
                _writer.write(toWrite);
                _stringWriter.append(toWrite);
        }
        
        private static byte[] EncryptSymmetric(final byte[] toEncrypt, final SecretKey key) {
                try {
                        final Cipher cipher = Cipher.getInstance(SymmetricAlgorithm + SymmetricAlgorithmParameters);
                        cipher.init(Cipher.ENCRYPT_MODE, key);
                        //could use modulus
                        final int length = (int) ((Math.ceil(toEncrypt.length / 16f)) * 16);
                        final byte[] toEncryptSizeAdjusted = Arrays.copyOf(toEncrypt, length);
                        final byte[] result = cipher.doFinal(toEncryptSizeAdjusted);
                        return result;
                } catch (final NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
                                | IllegalBlockSizeException | BadPaddingException e) {
                        e.printStackTrace();
                        return null;
                }
        }
}