示例#1
0
 /**
  * Encrypts the given message using reverse RSA (encrypts with the private key) and returns the
  * ciphertext of the message in String form or null if the message could not be encrypted
  *
  * @param msg != null
  * @return ciphertext form of the message made from RSA encryption or null if the message could
  *     not be encrypted
  */
 public String encryptRSA(String msg) {
   try {
     Cipher cipher = Cipher.getInstance("RSA");
     cipher.init(Cipher.ENCRYPT_MODE, privRSAKey);
     byte[] msgBytes = msg.getBytes();
     String result = "";
     for (int i = 0; i < (int) Math.ceil(msgBytes.length * 1.0 / 100); i++) {
       byte[] c =
           cipher.doFinal(
               Arrays.copyOfRange(msgBytes, i * 100, Math.min((i + 1) * 100, msgBytes.length)));
       result += new Base64().encodeToString(c);
     }
     return result.replace("\r\n", "_").replace("\r", "~").replace("\n", "::");
   } catch (Exception e) {
     System.out.println("Could not encrypt the message with RSA");
     if (DEBUG) {
       e.printStackTrace();
     }
     return null;
   }
 }
示例#2
0
  /**
   * Decrypts the given encrypted message using reverse RSA, meaning that it uses the public key to
   * decrypt, and returns the decrypte message or null if the message could not be decrypted
   *
   * @param encMsg != null and encrypted with either this object or a similar object that has the
   *     proper decryption parameters
   * @return the string representation of the message that was decrypted or null if the message
   *     could not be decrypted
   */
  public String decryptRSA(String encMsg) {
    try {
      encMsg = encMsg.replace("::", "\n").replace("~", "\r").replace("_", "\r\n");
      Cipher cipher = Cipher.getInstance("RSA");
      cipher.init(Cipher.DECRYPT_MODE, pubRSAKey);
      String result = "";
      for (int i = 0; i < encMsg.length() / 178; i++) {
        String subMsg = encMsg.substring(i * 178, Math.min((i + 1) * 178, encMsg.length()));

        byte[] msgBytes = cipher.doFinal(new Base64().decode(subMsg));
        result += new String(msgBytes);
      }
      return result;
    } catch (Exception e) {
      System.out.println("Could not decrypt the message with RSA");
      if (DEBUG) {
        e.printStackTrace();
      }
      return null;
    }
  }
示例#3
0
  // Uses supplied hash algorithm
  static byte[] derive(
      char[] chars, byte[] salt, int ic, int n, int type, String hashAlgo, int blockLength) {

    // Add in trailing NULL terminator.  Special case:
    // no terminator if password is "\0".
    int length = chars.length * 2;
    if (length == 2 && chars[0] == 0) {
      chars = new char[0];
      length = 0;
    } else {
      length += 2;
    }

    byte[] passwd = new byte[length];
    for (int i = 0, j = 0; i < chars.length; i++, j += 2) {
      passwd[j] = (byte) ((chars[i] >>> 8) & 0xFF);
      passwd[j + 1] = (byte) (chars[i] & 0xFF);
    }
    byte[] key = new byte[n];

    try {
      MessageDigest sha = MessageDigest.getInstance(hashAlgo);

      int v = blockLength;
      int u = sha.getDigestLength();
      int c = roundup(n, u) / u;
      byte[] D = new byte[v];
      int s = roundup(salt.length, v);
      int p = roundup(passwd.length, v);
      byte[] I = new byte[s + p];

      Arrays.fill(D, (byte) type);
      concat(salt, I, 0, s);
      concat(passwd, I, s, p);

      byte[] Ai;
      byte[] B = new byte[v];
      byte[] tmp = new byte[v];

      int i = 0;
      for (; ; i++, n -= u) {
        sha.update(D);
        sha.update(I);
        Ai = sha.digest();
        for (int r = 1; r < ic; r++) Ai = sha.digest(Ai);
        System.arraycopy(Ai, 0, key, u * i, Math.min(n, u));
        if (i + 1 == c) break;
        concat(Ai, B, 0, B.length);
        BigInteger B1;
        B1 = new BigInteger(1, B).add(BigInteger.ONE);

        for (int j = 0; j < I.length; j += v) {
          BigInteger Ij;
          int trunc;

          if (tmp.length != v) tmp = new byte[v];
          System.arraycopy(I, j, tmp, 0, v);
          Ij = new BigInteger(1, tmp);
          Ij = Ij.add(B1);
          tmp = Ij.toByteArray();
          trunc = tmp.length - v;
          if (trunc >= 0) {
            System.arraycopy(tmp, trunc, I, j, v);
          } else if (trunc < 0) {
            Arrays.fill(I, j, j + (-trunc), (byte) 0);
            System.arraycopy(tmp, 0, I, j + (-trunc), tmp.length);
          }
        }
      }
    } catch (Exception e) {
      throw new RuntimeException("internal error: " + e);
    }
    return key;
  }