[英]Using my own key in an AES encryption algorithm implementation
我有以下代碼:
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));
}
}
和主要類別:
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();
}
}
}
如何使用我自己的密鑰? rawKey的用途是什么?
只要我在StackOverflow上,那就是我一直在爭奪的getRawKey
函數。 要使用密碼,請使用PBKDF2,它是Java內置的。 要創建隨機密鑰,請使用隨機數生成器new SecureRandom()
和SecretKeySpec
。
如果您的隨機數生成器曾經做過任何意外的事情,例如生成隨機數而不是充當確定性PRNG,則您的密鑰將是不同的,並且您可能永遠也不會再次解密密文。 這實際上是在Android上進行的更新之后發生的,其中替換了默認提供程序,並且RNG與以前的提供程序有所不同。
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) {
}
}
}
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