IT Knowledge Sharing | Interview questions

public static long checkTimeDifference(String time1,String time2){                //time1 and time 2 must be in HH:mm:ss format     SimpleDateFormat format = new SimpleDateFormat("HH:mm:ss");     Date date1;     Date date2;     long difference=0; try { date1 = format.parse(time1); date2 = format.parse(time2); difference = date2.getTime() - date1.getTime(); } catch (ParseException e) { e.printStackTrace(); } return difference;         }

java.security.InvalidKeyException: Illegal key size or default parameters Caused by: java.security.InvalidKeyException: Illegal key size or default parameters     at javax.crypto.Cipher.a(DashoA13*..) ~[na:1.6]     at javax.crypto.Cipher.a(DashoA13*..) ~[na:1.6]     at javax.crypto.Cipher.a(DashoA13*..) ~[na:1.6]     at javax.crypto.Cipher.init(DashoA13*..) ~[na:1.6]     at javax.crypto.Cipher.init(DashoA13*..) ~[na:1.6] -------------------------------------------------------------------------------------- There are key size restrictions with the default crypto files local_policy.jar and US_export_policy.jar comes with JDK – which limits it to 128. If the security policy you are using has a key size larger than this limit– then the above exception is thrown. Please follow these instructions... You need to patch your JDK with Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. For JDK1.5 vis...

Double Encryption and decryption using Blowfish and Base64 -------------------------------------------------------------- import java.security.NoSuchAlgorithmException; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.NoSuchPaddingException; import javax.crypto.SecretKey; import javax.crypto.spec.SecretKeySpec; import org.apache.commons.codec.binary.Base64; public class BlowfishCipher {  public static void main(String[] args) throws Exception {    KeyGenerator keygenerator = KeyGenerator.getInstance("Blowfish");       SecretKey secretkey = keygenerator.generateKey();        Cipher cipher = Cipher.getInstance("Blowfish");    // get the text to encrypt    String inputText = "User_ID=Test12&User_Timestamp=20121030040002";    System.out.println("Double Encryption..................for :"+inputText);    cipher.init(Ciph...

Blowfish Encryption Decryption using KeyGenerator ---------------------------------------------- import java.security.NoSuchAlgorithmException; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.NoSuchPaddingException; import javax.crypto.SecretKey; import javax.crypto.spec.SecretKeySpec; import org.apache.commons.codec.binary.Base64; public class BlowfishCipherExample {  public static void main(String[] args) throws Exception {    // create a key generator based upon the Blowfish cipher    KeyGenerator keygenerator = KeyGenerator.getInstance("Blowfish");    // create a secret key    SecretKey secretkey = keygenerator.generateKey();    // create a cipher based upon Blowfish    Cipher cipher = Cipher.getInstance("Blowfish");    // initialise cipher to with secret key      cipher.init(Cipher.ENCRYPT_MODE, secretkey); ...

First download jar from apache..  commons-codec-1.7.jar and add this to your lib... ----------------------------------------------------------------------------------------- import org.apache.commons.codec.binary.Base64; public class Base64TestUsingApacheCodec {   public static void main(String[] args) {     String testStr="Hello ! test this";     byte[] encodedBytes = Base64.encodeBase64( testStr .getBytes());     System.out.println("encodedBytes " + new String(encodedBytes));     byte[] decodedBytes = Base64.decodeBase64(encodedBytes);     System.out.println("decodedBytes " + new String(decodedBytes));  } } ================================================================

Image resizing/compression for linux  ImageMagick isn’t included in the default installations of Ubuntu and many other Linux distributions. To install it on Ubuntu, use the following command:     sudo apt-get install imagemagick ------------------------------------------------------------- Converting Between Formats convert a.png b.jpg You can also specify a compression level for JPEG images: convert a.png -quality 95 b.jpg --------------------------------------------------------------- Resizing Images The convert command can also quickly resize an image. Here you can asks ImageMagick to resize an image to 100 pixels in width and 50 pixels in height:     convert a.jpg -resize 100×50 b.jpg ------------------------------------------------------------   Reduce size of  all images with same name (No name change after reducing)  for fileName in *.jpg; do convert $fileName -quality 50 $fileName; done  -----------------...