Java tutorial
/* * This project has received funding from the European Unions Seventh * Framework Programme for research, technological development and * demonstration under grant agreement no FP7-601138 PERICLES. * * Copyright 2015 Anna Eggers, State- and Univeristy Library Goettingen * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package algorithm; import static main.Configuration.RESTORED_DIRECTORY; import static model.Criterion.CARRIER_PROCESSABILITY; import static model.Criterion.CARRIER_RESTORABILITY; import static model.Criterion.COMPRESSION; import static model.Criterion.DETECTABILITY; import static model.Criterion.ENCAPSULATION_METHOD; import static model.Criterion.ENCRYPTION; import static model.Criterion.PAYLOAD_ACCESSIBILITY; import static model.Criterion.PAYLOAD_RESTORABILITY; import static model.Criterion.STANDARDS; import static model.Criterion.VELOCITY; import static model.Criterion.VISIBILITY; import java.io.File; import java.io.IOException; import java.util.ArrayList; import java.util.List; import org.apache.commons.io.FileUtils; import org.apache.commons.io.filefilter.SuffixFileFilter; import model.PayloadSegment; import model.RestoredFile; import model.Scenario; /** * This method adds text at the end of a JPEG file. * * @author Anna Eggers */ public class JPEGTextAdding extends AbstractAlgorithm { @Override public File encapsulate(File carrier, List<File> payloadList) throws IOException { File outputFile = getOutputFile(carrier); for (File payload : payloadList) { append(outputFile, payload, carrier); } return outputFile; } @Override public List<RestoredFile> restore(File encapsulatedData) throws IOException { List<RestoredFile> restoredFiles = new ArrayList<RestoredFile>(); String restoredCarrierName = getRestoredCarrierName(encapsulatedData); byte[] encapsulatedBytes = FileUtils.readFileToByteArray(encapsulatedData); String carrierPath = ""; String carrierChecksum = ""; while (true) { PayloadSegment payloadSegment = PayloadSegment.getPayloadSegment(encapsulatedBytes); if (payloadSegment == null) { RestoredFile carrier = new RestoredFile(restoredCarrierName); FileUtils.writeByteArrayToFile(carrier, encapsulatedBytes); carrier.validateChecksum(carrierChecksum); carrier.wasCarrier = true; carrier.algorithm = this; carrier.relatedFiles.addAll(restoredFiles); carrier.originalFilePath = carrierPath; for (RestoredFile file : restoredFiles) { file.relatedFiles.add(carrier); file.algorithm = this; } restoredFiles.add(carrier); return restoredFiles; } else { RestoredFile payload = new RestoredFile(RESTORED_DIRECTORY + payloadSegment.getPayloadName()); FileUtils.writeByteArrayToFile(payload, payloadSegment.getPayloadBytes()); payload.validateChecksum(payloadSegment.getPayloadChecksum()); payload.wasPayload = true; payload.originalFilePath = payloadSegment.getPayloadPath(); payload.relatedFiles.addAll(restoredFiles); for (RestoredFile file : restoredFiles) { file.relatedFiles.add(payload); } restoredFiles.add(payload); encapsulatedBytes = PayloadSegment.removeLeastPayloadSegment(encapsulatedBytes); carrierChecksum = payloadSegment.getCarrierChecksum(); carrierPath = payloadSegment.getCarrierPath(); } } } /** * Appends the payload bytes at the end of the carrier file. * * @param outputCarrier * carrier bytes + payload bytes * @param payload * file to be appended */ private void append(File outputCarrier, File payload, File originalCarrier) throws IOException { PayloadSegment metadata = new PayloadSegment(originalCarrier, payload, this); FileUtils.writeByteArrayToFile(outputCarrier, metadata.getPayloadSegmentBytes(), true); } @Override Scenario defineScenario() { Scenario scenario = new Scenario("JPEG text scenario"); scenario.description = "This is the ideal scenario to use the JPEG text adding algorithm."; scenario.setCriterionValue(ENCAPSULATION_METHOD, EMBEDDING); scenario.setCriterionValue(VISIBILITY, INVISIBLE); scenario.setCriterionValue(DETECTABILITY, DETECTABLE); scenario.setCriterionValue(CARRIER_RESTORABILITY, YES); scenario.setCriterionValue(PAYLOAD_RESTORABILITY, YES); scenario.setCriterionValue(CARRIER_PROCESSABILITY, YES); scenario.setCriterionValue(PAYLOAD_ACCESSIBILITY, NO); scenario.setCriterionValue(ENCRYPTION, NO); scenario.setCriterionValue(COMPRESSION, NO); scenario.setCriterionValue(VELOCITY, NO); scenario.setCriterionValue(STANDARDS, NO); return scenario; } @Override SuffixFileFilter configureCarrierFileFilter() { ArrayList<String> supportedFormats = new ArrayList<String>(); supportedFormats.add("jpg"); supportedFormats.add("JPG"); supportedFormats.add("JPEG"); supportedFormats.add("jpeg"); return new SuffixFileFilter(supportedFormats); } @Override SuffixFileFilter configurePayloadFileFilter() { ArrayList<String> supportedFormats = new ArrayList<String>(); supportedFormats.add("txt"); supportedFormats.add("json"); supportedFormats.add("xml"); // TODO: this probably supports a lot more data formats! return new SuffixFileFilter(supportedFormats); } @Override SuffixFileFilter configureDecapsulationFileFilter() { return configureCarrierFileFilter(); } @Override public String getName() { return "JPEG text adding"; } @Override public String getDescription() { String description = "This algorithm appends payload text to the end of carrier JPEG files." + " It is able to restore the JPEG and the text file correctly in every bit.\n" + "This technique is not standardised. In some " + "cases it might produce problems for displaying the encapsulated JPEG file. " + "However, these problems are rare and won't last after the restoration of the" + " original files."; return description; } /** * Not more than one carrier possible. */ @Override public boolean fulfilledTechnicalCriteria(File carrier, List<File> payloadList) { return carrier.isFile() && payloadList.size() > 0; } }