Tag Archives: Password Encryption and Decryption

[Solved] javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher


Generally this exception happen while having some encrypted character which where used for URL parameter encryption.

Exception in thread "main" javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher
	at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:936)
	at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:847)
	at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:446)
	at javax.crypto.Cipher.doFinal(Cipher.java:2165)
	at security.EncryptionDecryptionURLParam.main(EncryptionDecryptionURLParam.java:51)

Solution :

Use below line of statements. Follow example below for more detail.

Not Use :

 byte[] decryptedPassword = cipher.doFinal(decodeStr.getBytes());

Use:

byte[] base64decodedTokenArr = Base64.decodeBase64(decodeStr.getBytes());
byte[] decryptedPassword = cipher.doFinal(base64decodedTokenArr);

Example :

Issues Solution

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How to do Encryption and Decryption for plain text/password in JAVA


Java code for Encryption and Decryption of plain text. In below code encrypting plain text encrypted by using Key by algorithm “AES/ECB/PKCS5Padding“ and Decryption again in plain text.

Pre-Requisite :

  • Java 7 or 8
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
public class EncryptionDecryption {

	public static void main(String[] args) throws Exception {
	    byte[] input = "facingissuesonit.com".getBytes();
	    byte[] keyBytes = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
	        0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };

	    SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");

	    Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");

	    System.out.println(new String(input));

	    // Encryption pass
	    cipher.init(Cipher.ENCRYPT_MODE, key);

	    byte[] cipherText = new byte[cipher.getOutputSize(input.length)];
	    int ctLength = cipher.update(input, 0, input.length, cipherText, 0);
	    ctLength += cipher.doFinal(cipherText, ctLength);
	    System.out.println(new String(cipherText));
	    System.out.println(ctLength);

	    // Decryption pass
	    cipher.init(Cipher.DECRYPT_MODE, key);
	    byte[] plainText = new byte[cipher.getOutputSize(ctLength)];
	    int ptLength = cipher.update(cipherText, 0, ctLength, plainText, 0);
	    ptLength += cipher.doFinal(plainText, ptLength);
	    System.out.println(new String(plainText));
	    System.out.println(ptLength);
	  }

}

More Sample Code

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