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  1. import java.io.DataInputStream;
  2. import java.io.IOException;
  3. import java.math.BigInteger;
  4. //import java.util.Base64;
  5.  
  6. // P = 137
  7. // Q = 131
  8. // E = 3
  9. // Public keys (n,e) = (17947, 3) and private keys (n, d) = (17947, 11787).
  10.  
  11. public class RSAMoreTest {
  12.  
  13.     private BigInteger p;
  14.     private BigInteger q;
  15.     private BigInteger n;
  16.     private BigInteger phi;
  17.     private BigInteger e;
  18.     private BigInteger d;
  19.     //private int bitlength = 1024;
  20.     //private SecureRandom r;
  21.  
  22.     private RSAMoreTest()
  23.     {
  24.         p = BigInteger.valueOf(137);
  25.         q = BigInteger.valueOf(131); // some value q
  26.         n = p.multiply(q); // modulus, n = pq
  27.         e = BigInteger.valueOf(3); // public key
  28.         d = BigInteger.valueOf(11787); // private key
  29.         phi = p.subtract(BigInteger.ONE).multiply(q.subtract(BigInteger.ONE));
  30.  
  31.         while (phi.gcd(e).compareTo(BigInteger.ONE) > 0 && e.compareTo(phi) < 0)
  32.         {
  33.             e.add(BigInteger.ONE);
  34.         }
  35.         d = e.modInverse(phi);
  36.     }
  37.  
  38.     @SuppressWarnings("deprecation")
  39.     public static void main(String[] args) throws IOException
  40.     {
  41.         RSAMoreTest rsa = new RSAMoreTest();
  42.         DataInputStream in = new DataInputStream(System.in);
  43.         String teststring;
  44.  
  45.         System.out.println("Enter the plain text:");
  46.         teststring = in.readLine();
  47.         System.out.println("Encrypting String: " + teststring);
  48.         System.out.println("String in Bytes: "
  49.                 + bytesToString(teststring.getBytes()));        
  50.         //Encrypt
  51.         byte[] encrypted = rsa.encrypt(teststring.getBytes());
  52.         //Decryption
  53.         byte[] decrypted = rsa.decrypt(encrypted);
  54.  
  55.         System.out.println("Decrypting Bytes: " + bytesToString(decrypted));
  56.         System.out.println("Decrypting String: " + new String(decrypted));
  57.  
  58.         //System.out.println("Encrypting Numbers: " + rsa.e.toString() + ", " + rsa.n.toString());
  59.         //System.out.println("Decrypting Numbers: " + rsa.d.toString() + ", " + rsa.n.toString());
  60.     }
  61.  
  62.     private static String bytesToString(byte[] encrypted)
  63.     {
  64.         String test = "";
  65.         for (byte b : encrypted)
  66.         {
  67.             test += Byte.toString(b);
  68.         }
  69.         return test;
  70.     }
  71.  
  72.     // Encrypt message
  73.     private byte[] encrypt(byte[] message)
  74.     {
  75.         return (new BigInteger(message)).modPow(e, n).toByteArray();
  76.     }
  77.  
  78.     // Decrypt message
  79.     private byte[] decrypt(byte[] message)
  80.     {
  81.         return (new BigInteger(message)).modPow(d, n).toByteArray();
  82.     }
  83. }
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin
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Standard input is empty
compilation info 
Main.java:11: error: class RSAMoreTest is public, should be declared in a file named RSAMoreTest.java
public class RSAMoreTest {
       ^
1 error
stdout
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Standard output is empty
https://ideone.com/0BRyBT
language:
Java (HotSpot 12)
created:
6 years ago
visibility:
secret

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