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    <pre><code>import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.BufferedReader; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.FileReader; import java.io.IOException; import java.io.InputStream; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.math.BigInteger; import java.security.Key; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.PrivateKey; import java.security.PublicKey; import java.security.spec.KeySpec; import java.security.spec.RSAPrivateKeySpec; import java.security.spec.RSAPublicKeySpec; import javax.crypto.Cipher; import javax.crypto.CipherInputStream; import javax.crypto.CipherOutputStream; class RSA{ public static void main(String[] args) throws Exception { generateKeys(); rsaEncrypt("plaintext.txt", "encrypted.txt"); rsaDecrypt("encrypted.txt", "decrypted.txt"); } public static void generateKeys() throws Exception { KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA"); kpg.initialize(2048); KeyPair kp = kpg.genKeyPair(); PublicKey publicKey = kp.getPublic(); PrivateKey privateKey = kp.getPrivate(); System.out.println("keys created"); KeyFactory fact = KeyFactory.getInstance("RSA"); RSAPublicKeySpec pub = fact.getKeySpec(publicKey, RSAPublicKeySpec.class); RSAPrivateKeySpec priv = fact.getKeySpec(privateKey, RSAPrivateKeySpec.class); saveToFile("public.key", pub.getModulus(), pub.getPublicExponent()); saveToFile("private.key", priv.getModulus(), priv.getPrivateExponent()); System.out.println("keys saved"); } public static void saveToFile(String fileName, BigInteger mod, BigInteger exp) throws IOException { ObjectOutputStream fileOut = new ObjectOutputStream( new BufferedOutputStream(new FileOutputStream(fileName))); try { fileOut.writeObject(mod); fileOut.writeObject(exp); } catch (Exception e) { throw new IOException("Unexpected error"); } finally { fileOut.close(); System.out.println("Closed writing file."); } } // Return the saved key static Key readKeyFromFile(String keyFileName) throws IOException { InputStream in = new FileInputStream(keyFileName); ObjectInputStream oin = new ObjectInputStream(new BufferedInputStream( in)); try { BigInteger m = (BigInteger) oin.readObject(); BigInteger e = (BigInteger) oin.readObject(); KeyFactory fact = KeyFactory.getInstance("RSA"); if (keyFileName.startsWith("public")) return fact.generatePublic(new RSAPublicKeySpec(m, e)); else return fact.generatePrivate(new RSAPrivateKeySpec(m, e)); } catch (Exception e) { throw new RuntimeException("Spurious serialisation error", e); } finally { oin.close(); System.out.println("Closed reading file."); } } // Use this PublicKey object to initialize a Cipher and encrypt some data public static void rsaEncrypt(String file_loc, String file_des) throws Exception { FileReader file = new FileReader("C://myprograms//plaintext.txt"); BufferedReader reader = new BufferedReader(file); String text = ""; String line = reader.readLine(); while(line!= null) { text += line; line = reader.readLine(); } reader.close(); System.out.println(text); byte[] data = new byte[32]; int i; System.out.println("start encyption"); Key pubKey = readKeyFromFile("public.key"); Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, pubKey); FileInputStream fileIn = new FileInputStream(file_loc); FileOutputStream fileOut = new FileOutputStream(file_des); CipherOutputStream cipherOut = new CipherOutputStream(fileOut, cipher); // Read in the data from the file and encrypt it while ((i = fileIn.read(data)) != -1) { cipherOut.write(data, 0, i); } // Close the encrypted file cipherOut.close(); fileIn.close(); System.out.println("encrypted file created"); } // Use this PublicKey object to initialize a Cipher and decrypt some data public static void rsaDecrypt(String file_loc, String file_des) throws Exception { byte[] data = new byte[32]; int i; System.out.println("start decyption"); Key priKey = readKeyFromFile("private.key"); Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.DECRYPT_MODE, priKey); FileInputStream fileIn = new FileInputStream(file_loc); CipherInputStream cipherIn = new CipherInputStream(fileIn, cipher); FileOutputStream fileOut = new FileOutputStream(file_des); // Write data to new file while ((i = cipherIn.read()) != -1) { fileOut.write(i); } // Close the file fileIn.close(); cipherIn.close(); fileOut.close(); System.out.println("decrypted file created"); } } </code></pre> <p>This program encrypts the text in plaintext.txt file and saves the cipher text in encrypted.txt file. Similarly decryption is done using encrypted.txt file and plain text is saved in decrypted.txt file .#</p>
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A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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