Question

我有以下代码：

import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class AESHelper {

    public static String encrypt(String seed, String cleartext) throws Exception {

        byte[] rawKey = getRawKey(seed.getBytes());
        byte[] result = encrypt(rawKey, cleartext.getBytes());
        return toHex(result);
    }

    public static String decrypt(String seed, String encrypted) throws Exception {
        byte[] rawKey = getRawKey(seed.getBytes());
        byte[] enc = toByte(encrypted);
        byte[] result = decrypt(rawKey, enc);
        return new String(result);
    }

    private static byte[] getRawKey(byte[] seed) throws Exception {
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
        sr.setSeed(seed);
        kgen.init(128, sr); // 192 and 256 bits may not be available
        SecretKey skey = kgen.generateKey();
        byte[] raw = skey.getEncoded();
        return raw;
    }

    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        byte[] encrypted = cipher.doFinal(clear);
        return encrypted;
    }

    private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        byte[] decrypted = cipher.doFinal(encrypted);
        return decrypted;
    }

    public static String toHex(String txt) {
        return toHex(txt.getBytes());
    }
    public static String fromHex(String hex) {
        return new String(toByte(hex));
    }

    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));
    }
}

和主要课程：

public class MainActivity extends Activity {

    String seedValue = "This Is MySecure";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        String normalText = "VIJAY";
        String normalTextEnc;

        try{
            normalTextEnc = AESHelper.encrypt(seedValue, normalText);
            String normalTextDec = AESHelper.decrypt(seedValue, normalTextEnc);
            TextView txe = new TextView(this);
            txe.setTextSize(14);
            txe.setText("Normal Text ::" + normalText + " \n Encrypted Value :: " + normalTextEnc + " \n Decrypted value :: " + normalTextDec);
            setContentView(txe);
        }catch(Exception e){
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

如何使用自己的密钥？ rawKey有什么用？

Answer 1

这就是我在StackOverflow上一直在与之斗争的getRawKey功能。要使用密码，请使用PBKDF2，它构建为Java。要创建随机密钥，请使用随机数生成器new SecureRandom()和SecretKeySpec。

如果您的随机数生成器出现意外情况，例如：生成随机数而不是作为确定性PRNG，您的密钥将不相同，您可能永远不会再次解密您的密文。这实际上发生在Android更新之后，其中更换了默认提供程序并且RNG与之前的RNG不同。

Answer 2

    package com.example.encryption;

    import javax.crypto.Cipher;
    import javax.crypto.SecretKey;
    import javax.crypto.spec.SecretKeySpec;
    import java.util.Base64;

    public class AESOwnKey {
        private Cipher ecipher;
        private Cipher dcipher;

        AESOwnKey(SecretKey key) {
            try {
                ecipher = Cipher.getInstance("AES");
                dcipher = Cipher.getInstance("AES");
                ecipher.init(Cipher.ENCRYPT_MODE, key);
                dcipher.init(Cipher.DECRYPT_MODE, key);
            } catch (Exception e) {
                System.out.println("Failed in initialization");
            }
        }

        public byte[] encrypt(String str) {
            try {
                byte[] utf8 = str.getBytes("UTF-8");
                byte[] enc = ecipher.doFinal(utf8);

                return Base64.getEncoder().encode(enc);
            } catch (Exception e) {
                System.out.println("Failed in Encryption");
            }
            return null;
        }

        public String decrypt(byte[] bytes) {
            try {
                byte[] dec = Base64.getDecoder().decode(bytes);

                byte[] utf8 = dcipher.doFinal(dec);

                return new String(utf8, "UTF-8");
            } catch (Exception e) {
                System.out.println("Failed in Decryption");
            }
            return null;
        }

        public static void main(String[] args) {
            try {
                String mykey = "1234567891234567";
                SecretKey key = new SecretKeySpec(mykey.getBytes(), "AES");
                AESOwnKey encrypter = new AESOwnKey(key);
                String original = "Testing encryption";
                System.out.println("Before Encryption   : " + original);
                byte[] encrypted = encrypter.encrypt(original);
                System.out.println("After Encryption   : " + encrypted);
                String decrypted = encrypter.decrypt(encrypted);
                System.out.println("After Decryption   : " + decrypted);

            } catch (Exception e) {
            }

        }
    }

在AES加密算法实现中使用我自己的密钥

2 个答案: