Android AES Decrypt decryptHex(String content, String username, String password)

Description

decrypt Hex

Declaration

public static String decryptHex(String content, String username,
            String password) 

Method Source Code

//package com.java2s;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class Main {
    private static final String UTF_8 = "UTF-8";
    private static final byte[] defaultIV = { 127, 24, 123, 23, 93, 7, 15,
            0, 9, 4, 8, 15, 16, 23, 42, 1 };

    public static String decryptHex(String content, String key) {
        try {//from w ww.ja v a 2  s  . c om
            byte[] contentBytes = hexDecode(content);
            byte[] result = decrypt(contentBytes, key);
            return new String(result, UTF_8);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return null;
    }

    public static String decryptHex(String content, String username,
            String password) {
        return decryptHex(content, password + username);
    }

    public static byte[] hexDecode(String data) {
        byte[] r = new byte[data.length() / 2];

        char[] a = data.toCharArray();

        for (int i = 0; i < a.length; i += 2) {
            char c1 = a[i], c2 = a[i + 1];
            int v1 = valueOf(c1);
            int v2 = valueOf(c2);
            r[i >> 1] = (byte) ((((v1 & 0xf) << 4) | (v2 & 0xf)) & 0xff);
        }

        return r;
    }

    public static byte[] decrypt(byte[] content, String key) {
        try {
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            IvParameterSpec ivs = new IvParameterSpec(defaultIV);
            cipher.init(Cipher.DECRYPT_MODE, getSecretKey(key), ivs);

            return cipher.doFinal(content);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    private static int valueOf(char c) {
        c = Character.toLowerCase(c);
        if (c >= '0' && c <= '9') {
            return c - '0';
        } else if (c >= 'a' && c <= 'f') {
            return c - 'a' + 10;
        }
        return -1;
    }

    private static SecretKeySpec getSecretKey(String key) {
        MessageDigest digest;
        try {
            digest = MessageDigest.getInstance("md5");
            SecretKeySpec keySpec = new SecretKeySpec(digest.digest(key
                    .getBytes(UTF_8)), "AES");
            return keySpec;
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return null;
    }
}

Related

1. decryptBase64Text(String key, String src)
2. decryptBytes(String key, byte[] src)
3. decryptBytes(String seed, byte[] encrypted)
4. decryptBytes(byte[] data, byte[] key)
5. decryptHex(String content, String key)
6. decryptNumberWithAES(String encrypted)
7. decryptUrlDecode(String dataPassword, String encrypted)
8. aesDecode(String seed, String encrypted)
9. decrypt(byte[] raw, byte[] encrypted)