Decrypt strings

Decrypt strings

Download the video tutorial which I've provided here to understand because it's little bit complicated to understand by my description

Click here to download decrypt strings video tutorial

Tutorial by euzada

Plz watch tutorial for clear understanding

Description

Encryption is the process of translating plain text data (plaintext) into something that appears to be random and meaningless (ciphertext). Decryption is the process of converting ciphertext back to plaintext.

To encrypt more than a small amount of data, symmetric encryption is used. A symmetric key is used during both the encryption and decryption processes. To decrypt a particular piece of ciphertext, the key that was used to encrypt the data must be used.


The goal of every encryption algorithm is to make it as difficult as possible to decrypt the generated ciphertext without using the key.

Encrypt Strings

Please copy the AESUtils class in your project first and then you can use it like this.

String encrypted = "";
String sourceStr = "This is any source string";
try {
    encrypted = AESUtils.encrypt(sourceStr);
    Log.d("TEST", "encrypted:" + encrypted);
} catch (Exception e) {
    e.printStackTrace();
}

Decrypt Strings

Please copy the AESUtils class in your project first and then you can use it like this.

String encrypted = "ANY_ENCRYPTED_STRING_HERE";
String decrypted = "";
try {
    decrypted = AESUtils.decrypt(encrypted);
    Log.d("TEST", "decrypted:" + decrypted);
} catch (Exception e) {
    e.printStackTrace();
}

AESUtils Class

The easiest way of implementing AES Encryption and Decryption in Android is to copy this class in your projects.

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class AESUtils 
{

    private static final byte[] keyValue =
            new byte[]{'c', 'o', 'd', 'i', 'n', 'g', 'a', 'f', 'f', 'a', 'i', 'r', 's', 'c', 'o', 'm'};


    public static String encrypt(String cleartext)
            throws Exception {
        byte[] rawKey = getRawKey();
        byte[] result = encrypt(rawKey, cleartext.getBytes());
        return toHex(result);
    }

    public static String decrypt(String encrypted)
            throws Exception {

        byte[] enc = toByte(encrypted);
        byte[] result = decrypt(enc);
        return new String(result);
    }

    private static byte[] getRawKey() throws Exception {
        SecretKey key = new SecretKeySpec(keyValue, "AES");
        byte[] raw = key.getEncoded();
        return raw;
    }

    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
        SecretKey skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        byte[] encrypted = cipher.doFinal(clear);
        return encrypted;
    }

    private static byte[] decrypt(byte[] encrypted)
            throws Exception {
        SecretKey skeySpec = new SecretKeySpec(keyValue, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        byte[] decrypted = cipher.doFinal(encrypted);
        return decrypted;
    }

    public static byte[] toByte(String hexString) {
        int len = hexString.length() / 2;
        byte[] result = new byte[len];
        for (int i = 0; i < len; i++)
            result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),
                    16).byteValue();
        return result;
    }

    public static String toHex(byte[] buf) {
        if (buf == null)
            return "";
        StringBuffer result = new StringBuffer(2 * buf.length);
        for (int i = 0; i < buf.length; i++) {
            appendHex(result, buf[i]);
        }
        return result.toString();
    }

    private final static String HEX = "0123456789ABCDEF";

    private static void appendHex(StringBuffer sb, byte b) {
        sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
    }
}

😅I think you understand what I'm trying to say if you don't understand plz refer the video tutorial in this post....