//참조한 문서
//http://stackoverflow.com/questions/13389870/android-4-2-broke-my-aes-encrypt-decrypt-code
public class SimpleCrypto {
private final static String HEX = "0123456789ABCDEF";
private final static int JELLY_BEAN_4_2 = 17;
// 암호화에 사용할 키. 원하는 값으로 바꿔주자.
private final static byte[] key = {(byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x00 };
/**
* AES 암호화
* @param seed 암호화에 사용할 seed
* @param cleartext 암호화 할 문자열
* @return 암호화된 문자열
* @throws Exception 암호화 key 사이즈가 192bit 또는 128bit로 감소함.
*/
public static String encrypt(String seed, String cleartext) throws Exception {
if (cleartext == null || cleartext == "") return null;
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext.getBytes());
String fromHex = toHex(result);
String base64 = new String(Base64.encodeToString(fromHex.getBytes(), 0));
return base64;
}
/**
* AES 복호화
* @param seed 복호화에 사용할 seed
* @param encrypted 복호화 할 문자열
* @return 복호화한 문자열
* @throws Exception 암호화 key 사이즈가 192bit 또는 128bit로 감소함.
*/
public static String decrypt(String seed, String encrypted) throws Exception {
if (encrypted == null || encrypted == "") return null;
byte[] seedByte = seed.getBytes();
System.arraycopy(seedByte, 0, key, 0, ((seedByte.length String base64 = new String(Base64.decode(encrypted, 0));
byte[] rawKey = getRawKey(seedByte);
byte[] enc = toByte(base64);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}
public static byte[] encryptBytes(String seed, byte[] cleartext) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext);
return result;
}
public static byte[] decryptBytes(String seed, byte[] encrypted) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = decrypt(rawKey, encrypted);
return result;
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = null;
if (android.os.Build.VERSION.SDK_INT >= JELLY_BEAN_4_2) {
sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");
} else {
sr = SecureRandom.getInstance("SHA1PRNG");
}
sr.setSeed(seed);
try {
kgen.init(256, sr);
// kgen.init(128, sr);
} catch (Exception e) {
// Log.w(LOG, "This device doesn't suppor 256bits, trying 192bits.");
try {
kgen.init(192, sr);
} catch (Exception e1) {
// Log.w(LOG, "This device doesn't suppor 192bits, trying 128bits.");
kgen.init(128, sr);
}
}
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");
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");
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 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 appendHex(result, buf[i]);
}
return result.toString();
}
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
}
}
