source: trunk/src/org/expeditee/encryption/io/EncryptedExpReader.java@ 1415

package org.expeditee.encryption.io;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.lang.reflect.Method;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Base64;
import java.util.List;
import java.util.function.BiConsumer;
import java.util.function.Predicate;

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.core.Point;
import org.expeditee.encryption.CryptographyConstants;
import org.expeditee.encryption.items.surrogates.EncryptionDetail;
import org.expeditee.encryption.items.surrogates.Label;
import org.expeditee.encryption.items.surrogates.Label.LabelResult;
import org.expeditee.gui.Frame;
import org.expeditee.gui.FrameIO;
import org.expeditee.io.Conversion;
import org.expeditee.io.DefaultFrameWriter;
import org.expeditee.io.ExpReader;
import org.expeditee.items.Constraint;
import org.expeditee.items.Item;
import org.expeditee.items.Text;
import org.expeditee.settings.identity.secrets.KeyList;

public class EncryptedExpReader extends ExpReader implements CryptographyConstants {
        
        private static final String ENCRYPTED_EXP_FLAG = "EncryptedExp";
        private static final String labelProfile = "Profile";
        private static final String labelNone = "None";
        private SecretKey personalKey;
        private boolean accessDenied = false;
        private boolean _readingSurrogates;
        private static final Predicate<String> endOfSection = s -> s.equals(EncryptedExpWriter.TERMINATOR + "") || s.equals(EncryptedExpWriter.TERMINATOR_WITH_CONTINUATION);

        public static boolean isEncryptedExpediteeFile(final String path) throws IOException {
                BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream(path), "UTF-8"));
                String firstLine = in.readLine();
                in.close();
                if (firstLine == null) return false;
                return firstLine.startsWith(ENCRYPTED_EXP_FLAG);
        }
        
        public EncryptedExpReader(String frameName) {
                super(frameName);
        }
        
        public int getVersionEnc(String fullpath) {
                try {
                        BufferedReader reader = new EncryptedLineReader(new BufferedReader(new FileReader(fullpath)));
                        String next = "";
                        // First read the header lines until we get the version number
                        while (reader.ready() && !(next = reader.readLine()).equals("Z")) {
                                if (isValidLine(next)) {
                                        Character tag = getTag(next);
                                        String value = getValue(next);
                                        if (tag.equals('V')) {
                                                reader.close();
                                                return Integer.parseInt(value);
                                        }
                                }
                        }
                        reader.close();
                } catch (Exception e) {
                }
                return -1;
        }
        
        @Override
        public Frame readFrame(final String fullPath) throws IOException {
                Reader in = new InputStreamReader(new FileInputStream(fullPath), "UTF-8");
                return readFrame(new EncryptedLineReader(in));
        }
        
        @Override
        public Frame readFrame(BufferedReader reader) throws IOException {
                if (accessDenied) { return null; }
                
                _readingSurrogates = false;
                _reader = reader;
                String next = "";
                Frame newFrame = new Frame();
                List<DelayedAction> delayedActions = new ArrayList<DelayedAction>();
                newFrame.setName(_frameName);
                
                try {
                        // First read all the header lines
                        next = readTheHeader(newFrame);
                        
                        // Now read all the items
                        next = readTheItems(newFrame, delayedActions);
                        
                        // Read the lines
                        next = readTheLines(newFrame);

                        // Read the constraints
                        next = readTheConstraints();
                        
                        if (next.equals(EncryptedExpWriter.TERMINATOR_WITH_CONTINUATION)) {
                                // Read the surrogates
                                _readingSurrogates = true;
                                next = readTheItems(newFrame, delayedActions);
                                _readingSurrogates = false;
                        }
                        
                        for(DelayedAction action: delayedActions) {
                                action.exec();
                        }

                        // Read the stats
                        next = readTheStats(newFrame);
                } catch (Exception e) {
                        e.printStackTrace();
                        System.out.println("Error reading frame file line: " + next + " " + e.getMessage());
                }
                
                _reader.close();
                FrameIO.setSavedProperties(newFrame);
                newFrame.setChanged(false);

                return newFrame;
        }
        
        protected String readTheItems(Frame newFrame, List<DelayedAction> delayedActions) throws IOException {
                BiConsumer<Item, String> primaryAdd = (item, line) -> newFrame.addItem(item);
                BiConsumer<Item, String> surrogateAdd = (item, line) -> {
                        int parentID = Integer.parseInt(line.split(" ")[1]);
                        Item parent = newFrame.getItemWithID(parentID);
                        newFrame.addToSurrogatesOnLoad(item, parent);
                };
                
                if (_readingSurrogates) {
                        return readLineAfterLine(true, surrogateAdd, delayedActions);
                } else {
                        return readLineAfterLine(false, primaryAdd, delayedActions);
                }
        }
        
        @Override
        protected String readTheConstraints() throws IOException, Exception {
                String next = null;
                while (_reader.ready() && !endOfSection.test(next = _reader.readLine())) {
                        if (isValidLine(next)) {
                                Point idtype = separateValues(next.substring(2));
                                // The next line must be the endpoints
                                if (!_reader.ready()) {
                                        throw new Exception("Unexpected end of file");
                                }
                                next = _reader.readLine();
                                Point startend = separateValues(next.substring(2));

                                Item a = _linePoints.get(startend.getX());
                                Item b = _linePoints.get(startend.getY());

                                new Constraint(a, b, idtype.getX(), idtype.getY());
                        }
                }
                return next;
        }
        
        private String readLineAfterLine(boolean isSurrogate, BiConsumer<Item, String> storeResult, List<DelayedAction> delayedActions) throws IOException {
                String next = null;
                Item currentItem = null;
                
                while (_reader.ready() && !endOfSection.test(next = _reader.readLine())) {
                        if (!isValidLine(next)) {
                                continue;
                        }
                        
                        String tag = getTagEnc(next);
                        if (next.startsWith(DefaultFrameWriter.TYPE_AND_ID_STR + " ")) {
                                currentItem = newItem(next);
                                _linePoints.put(currentItem.getID(), currentItem);
                                if (!isSurrogate) {
                                        storeResult.accept(currentItem, next);
                                }
                                EncryptionDetail unencryptedOnSave = new EncryptionDetail(EncryptionDetail.Type.UnencryptedOnSave);
                                currentItem.setEncryptionDetailForTag(tag + "", unencryptedOnSave);
                        } else if (next.startsWith("SurrogateFor")) {
                                if (isSurrogate) {
                                        storeResult.accept(currentItem, next);
                                }
                        } else if (currentItem != null && actionShouldBeDelayed(tag.charAt(0))) { 
                                delayedActions.add(new DelayedAction(currentItem, next));
                        } else if (currentItem != null) {
                                processBodyLine(currentItem, next);
                        } else {
                                System.err.println("Error while reading in frame (ExpReader): Found body line but no current item to apply it to.");
                        }
                }
                
                return next;
        }
        
        @Override
        protected void processBodyLine(Item item, String line) {
                // separate the tag from the value
                String tag = getTagEnc(line);
                String value = getValue(line);
                boolean isEncryptedLine = isEncryptedLine(line);
                
                if (item.isSurrogate() && isEncryptedLine) {
                        // Surrogates should never have encrypted body lines.
                        return;
                }
                
                // Attempt to decrypt the line if necessary.
                if (isEncryptedLine) {
                        LabelResult res = Label.getLabel(item.getEncryptionLabel());
                        if (res == LabelResult.SuccessResolveLabelToKey) {
                                EncryptionDetail reencryptOnSave = new EncryptionDetail(EncryptionDetail.Type.ReencryptOnSave);
                                item.setEncryptionDetailForTag(tag, reencryptOnSave);
                                SecretKey key = new SecretKeySpec(res.key, SymmetricAlgorithm);
                                byte[] decryptedBytes = DecryptSymmetric(Base64.getDecoder().decode(value), key);
                                value = new String(decryptedBytes);                             
                        } else {
                                EncryptionDetail undecipheredValueOnSave = new EncryptionDetail(EncryptionDetail.Type.UseUndecipheredValueOnSave);
                                undecipheredValueOnSave.setUndecipheredValue(getValue(line));
                                item.setEncryptionDetailForTag(tag, undecipheredValueOnSave);
                                return;
                        }
                } else {
                        EncryptionDetail unencryptedOnSave = new EncryptionDetail(EncryptionDetail.Type.UnencryptedOnSave);
                        item.setEncryptionDetailForTag(tag, unencryptedOnSave);
                        if (item.isSurrogate()) {
                                item.setTagNotInherited(tag);
                        }
                }
                
                // Process the line
                Method toRun = tag.startsWith("_") ? _ItemTagsExt.get(tag) : _ItemTags.get(tag.charAt(0));
                if (toRun == null) {
                        System.out.println("Error accessing tag method: " + tag);
                }
                Object[] vals = Conversion.Convert(toRun, value);
                try {
                        if (vals != null) {
                                toRun.invoke(item, vals);
                        }
                } catch (Exception e) {
                        System.out.println("Error running tag method: " + tag);
                        e.printStackTrace();
                }
        }
        
        protected static String getValue(String line) {
                String[] split = line.split(" ");
                if (split.length >= 2) {
                        return line.substring(split[0].length()).trim();
                } else {
                        return null;
                }
        }
        
        private static String getTagEnc(String line) {
                char charAtZero = line.charAt(0);
                if (charAtZero == '_') {
                        return line.split(" ")[0];
                } else {
                        return charAtZero + "";
                }
        }
                
        private static boolean isEncryptedLine(String line) {
                if (line.startsWith("S") || line.startsWith("_el")) {
                        return false;
                }               
                if (line.length() > 2) {
                        return line.charAt(1) == 'E';
                } else {
                        return false;
                }
        }
        
        private static byte[] DecryptSymmetric(final byte[] toDecrypt, final SecretKey key) {
                try {
                        final Cipher cipher = Cipher.getInstance(SymmetricAlgorithm + SymmetricAlgorithmParameters);
                        cipher.init(Cipher.DECRYPT_MODE, key);
                        final byte[] decryptedBytes = cipher.doFinal(toDecrypt);
                        int indexOfZero = decryptedBytes.length - 1;
                        for (int i = decryptedBytes.length - 1; i >= 0; i--) {
                                if (decryptedBytes[i] != (byte) 0) {
                                        indexOfZero = i + 1;
                                        break;
                                }
                        }
                        if (indexOfZero < 0) { return decryptedBytes; }
                        else { return Arrays.copyOf(decryptedBytes, indexOfZero); }
                } catch (final NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
                                | IllegalBlockSizeException | BadPaddingException e) {
                        e.printStackTrace();
                        return null;
                }
        }

        private class EncryptedLineReader extends BufferedReader {
                private boolean noneMode = false;
                
                public EncryptedLineReader(Reader in) {
                        super(in);
                }
                
                @Override
                /**
                 * Reads a line from an encrypted exp file that uses an encryption specified by the first line of the file.
                 * Returns that line to process, null if the currently logged in users doesn't own the appropriate key (access denied).
                 */
                public String readLine() throws IOException {
                        String line = super.readLine();
                        
                        if (line.isEmpty()) {
                                return "";
                        }
                        
                        if (noneMode) {
                                return line;
                        }
                        
                        if (line.startsWith(ENCRYPTED_EXP_FLAG)) {
                                String label = line.replace(ENCRYPTED_EXP_FLAG, "");
                                // if using Profile label, use personal key
                                if (label.equals(labelProfile)) {
                                        Text text = KeyList.PersonalKey.get();
                                        byte[] keyBytes = Base64.getDecoder().decode(text.getData().get(0));
                                        personalKey = new SecretKeySpec(keyBytes, SymmetricAlgorithm);
                                        return readLine();
                                } else if (label.equals(labelNone)) {
                                        noneMode = true;
                                        return readLine();
                                } else {
                                        personalKey = resolveLabel(label);
                                        if (personalKey == null) {
                                                return null;
                                        } else {
                                                return readLine();
                                        }
                                }
                        }
                        
                        // decrypt line and return result
                        byte[] toDecrypt = Base64.getDecoder().decode(line);
                        byte[] decrypted = DecryptSymmetric(toDecrypt, personalKey);
                        if (decrypted == null) {
                                accessDenied = true;
                                return null; // access denied
                        } else {
                                String decryptedLine = new String(decrypted);
                                if (decryptedLine.startsWith("Z")) { 
                                        return decryptedLine.trim();
                                } else { 
                                        return decryptedLine;
                                }
                        }
                }
                
                private SecretKeySpec resolveLabel(String label) {
                        LabelResult res = Label.getLabel(label);
                        if (res == LabelResult.SuccessResolveLabelToKey) {
                                byte[] keyBytes = res.key;
                                return new SecretKeySpec(keyBytes, SymmetricAlgorithm);
                        }
                        return null;
                }
        }
}