Solution

README.md

@@ -2,4 +2,10 @@
 
 Project: Encryption-Decryption
 
-Go to the *src* directory, change *Crypto.java* and put your *.java* file(s) in it.
+Added two methods for encryption/description
+
+Command line support added 
+
+Work with files added
+
+New aes algorithm added (13.01.19)

protected.txt

@@ -0,0 +1 @@
+637E771EB77D5BA14AF2E60452B99CCF88D408880DE930CF81F2E7CD57F6C601

road_to_treasure.txt

@@ -0,0 +1 @@
+Welcome to hyperskill!

src/crypto/AesCryptoAlgorithm.java

@@ -0,0 +1,59 @@
+package crypto;import com.sun.org.apache.xerces.internal.impl.dv.util.HexBin;
+
+import javax.crypto.Cipher;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
+public class AesCryptoAlgorithm implements CryptoAlgorithm {
+
+    private static final String SECRET_KEY = "JustSecretString";
+
+    @Override
+    public String encryption(String message, String key) {
+        String encryptedMessage = "";
+        try {
+            if (!isValidKey(key)) {
+                System.out.println("Error: For the aes algorithm, key length must be 16, 24 or 32 symbols(bytes)");
+            }
+
+            IvParameterSpec ivParameter = new IvParameterSpec(SECRET_KEY.getBytes("UTF-8"));
+            SecretKeySpec secretKey = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
+
+            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+            cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivParameter);
+
+            byte[] bytes = cipher.doFinal(message.getBytes("UTF-8"));
+            encryptedMessage = HexBin.encode(bytes);
+        } catch (Throwable cause) {
+            System.out.println("Error: " + cause.getMessage());
+        }
+        return encryptedMessage;
+    }
+
+    @Override
+    public String decryption(String encryptedMessage, String key) {
+        String decryptedMessage = "";
+        try {
+            if (!isValidKey(key)) {
+                System.out.println("Error: For the aes algorithm, key length must be 16, 24 or 32 symbols(bytes)");
+            }
+
+            IvParameterSpec ivParameter = new IvParameterSpec(SECRET_KEY.getBytes("UTF-8"));
+            SecretKeySpec secretKey = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
+
+            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+            cipher.init(Cipher.DECRYPT_MODE, secretKey, ivParameter);
+
+            byte[] bytes = cipher.doFinal(HexBin.decode(encryptedMessage));
+            decryptedMessage = new String(bytes);
+        } catch (Throwable cause) {
+            System.out.println("Error: " + cause.getMessage());
+            cause.printStackTrace();
+        }
+        return decryptedMessage;
+    }
+
+    private static boolean isValidKey(String key) {
+        return key.length() == 16 || key.length() == 24 || key.length() == 32;
+    }
+}

src/crypto/Crypto.java

@@ -1,10 +1,98 @@
 package crypto;
 
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
 import java.util.Scanner;
 
 public class Crypto {
     public static void main(String[] args) {
         Scanner scanner = new Scanner(System.in);
-	// write your code here
+        String state = "enc";
+        String key = "";
+        String algName = "";
+        String message = "";
+        String result = "";
+        String in = "";
+        String out = "";
+
+        for (int i = 0; i < args.length; i++) {
+            if ("-mode".equals(args[i])) {
+                state = args[i + 1];
+                i++;
+            } else if ("-key".equals(args[i])) {
+                key = args[i + 1];
+                i++;
+            }else if ("-alg".equals(args[i])) {
+                algName = args[i + 1];
+                i++;
+            } else if ("-data".equals(args[i])) {
+                message = args[i + 1];
+                i++;
+            } else if ("-in".equals(args[i])) {
+                in = args[i + 1];
+                i++;
+            } else if ("-out".equals(args[i])) {
+                out = args[i + 1];
+                i++;
+            }
+        }
+
+        CryptoAlgorithm cryptoAlgorithm = CryptoAlgorithmFactory.getAlgorithm(algName);
+
+        if (key.equals("")) {
+            System.out.print("Enter key: ");
+            key = scanner.nextLine();
+        }
+
+        if (!in.equals("")) {
+            File input = new File(in);
+            if (input.exists()) {
+                try {
+                    message = new String(Files.readAllBytes(Paths.get(input.getPath())));
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            }
+        }
+
+        if (message.equals("")) {
+            System.out.print("Enter text: ");
+            message = scanner.nextLine();
+        }
+
+        if ("enc".equals(state)) {
+            result = cryptoAlgorithm.encryption(message, key);
+        }
+
+        if ("dec".equals(state)) {
+            result = cryptoAlgorithm.decryption(message, key);
+        }
+
+        if (out.equals("")) {
+            System.out.println(result);
+        } else {
+            File output = new File(out);
+            boolean created = true;
+            if (!output.exists()) {
+                try {
+                    created = output.createNewFile();
+                } catch (IOException e) {
+                    created = false;
+                    System.out.println("Cannot create the file: " + output.getPath());
+                }
+            }
+            if (created) {
+                try {
+                    FileWriter writer = new FileWriter(output);
+                    writer.write(result);
+                    writer.close();
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            }
+        }
     }
 }

src/crypto/CryptoAlgorithm.java

@@ -0,0 +1,4 @@
+package crypto;public interface CryptoAlgorithm {
+    String encryption(String message, String key);
+    String decryption(String encryptedMessage, String key);
+}

src/crypto/CryptoAlgorithmFactory.java

@@ -0,0 +1,9 @@
+package crypto;public class CryptoAlgorithmFactory {
+    public static CryptoAlgorithm getAlgorithm(String algName) {
+        if (algName.equals("aes")) {
+            return new AesCryptoAlgorithm();
+        } else {
+            return new SimpleCryptoAlgorithm();
+        }
+    }
+}

src/crypto/SimpleCryptoAlgorithm.java

@@ -0,0 +1,47 @@
+package crypto;public class SimpleCryptoAlgorithm implements CryptoAlgorithm {
+
+    @Override
+    public String encryption(String message, String key) {
+        String encrypt = "";
+        int secretKey = 0;
+        try {
+            secretKey = Integer.parseInt(key);
+        } catch (NumberFormatException ex) {
+            System.out.println("Error: For the simple algorithm, the key must be a number");
+        }
+        for (int i = 0; i < message.length(); i++) {
+            int index = message.charAt(i);
+
+            if (index != -1) {
+                int newIndex = index + secretKey;
+                char c = (char) newIndex;
+                encrypt += c;
+            } else {
+                encrypt += String.valueOf(index);;
+            }
+        }
+        return encrypt;    }
+
+    @Override
+    public String decryption(String encryptedMessage, String key) {
+        String encrypt = "";
+        int secretKey = 0;
+        try {
+            secretKey = Integer.parseInt(key);
+        } catch (NumberFormatException ex) {
+            System.out.println("Error: For the simple algorithm, the key must be a number");
+        }
+        for (int i = 0; i < encryptedMessage.length(); i++) {
+            int index = encryptedMessage.charAt(i);
+
+            if (index != -1) {
+                int newIndex = index - secretKey;
+                char c = (char) newIndex;
+                encrypt += c;
+            } else {
+                encrypt += String.valueOf(index);;
+            }
+        }
+        return encrypt;
+    }
+}