我已经在 Android 应用程序中实现了加密/解密。
我添加了一个 Encryption 类,该类已成为 Singleton 类。
部分代码如下:
public class Encryption {
private SecretKeySpec mKey = null;
private Cipher mCipher = null;
private byte[] mKeyBytes = null;
private AlgorithmParameterSpec mParamSpec = null;
private static Encryption sInstance;
public Encryption() {
byte[] iv = new byte[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
mParamSpec = new IvParameterSpec(iv);
mKeyBytes = getMD5(MD5_KEY.getBytes();
mKey = new SecretKeySpec(mKeyBytes, AES_TAG);
try {
mCipher = Cipher.getInstance(TRANSFORMATION_STR);
} catch (NoSuchAlgorithmException e) {
} catch (NoSuchPaddingException e) {
}
}
public static synchronized Encryption getInstance() {
if (sInstance == null) {
sInstance = new Encryption();
}
return sInstance;
}
public String encryptString(String strPwd) {
String strToEncripted = null;
strToEncripted = strPwd;
String result = null;
byte[] input = null;
byte[] cipherText = null;
int ctLength = 0;
try {
input = strToEncripted.getBytes(UTF8_STR);
mCipher.init(Cipher.ENCRYPT_MODE, mKey, mParamSpec);
cipherText = new byte[mCipher.getOutputSize(input.length)];
ctLength = mCipher.update(input, 0, input.length, cipherText, 0);
ctLength += mCipher.doFinal(cipherText, ctLength);
result = Base64.encodeToString(cipherText, Base64.DEFAULT)
.replace(NEWLINE_CHAR, EMPTY_CHAR).trim();
} catch (InvalidKeyException e) {
} catch (UnsupportedEncodingException e) {
} catch (InvalidAlgorithmParameterException e) {
} catch (ShortBufferException e) {
} catch (IllegalBlockSizeException e) {
} catch (BadPaddingException e) {
} catch (IllegalStateException e) {
}
return result;
}
public String decryptstring(byte[] encripted) {
String textDecrypt = "";
byte[] encriptedByteDecode64 = Base64.decode(encripted, Base64.DEFAULT);
byte[] plainText = new byte[mCipher.getOutputSize(encriptedByteDecode64.length)];
int ptLength = 0;
try {
mCipher.init(Cipher.DECRYPT_MODE, mKey, mParamSpec);
ptLength = mCipher.update(encriptedByteDecode64, 0, encriptedByteDecode64.length, plainText, 0);
ptLength += mCipher.doFinal(plainText, ptLength);
textDecrypt = (new String(plainText)).trim();
} catch (InvalidKeyException e) {
} catch (InvalidAlgorithmParameterException e) {
} catch (ShortBufferException e) {
} catch (IllegalBlockSizeException e) {
} catch (BadPaddingException e) {
}
return textDecrypt;
}
private String getMD5(String strKey) {
String key = strKey;
String result = null;
try {
MessageDigest algorithm = MessageDigest.getInstance(MD5_TAG);
algorithm.reset();
algorithm.update(key.getBytes(UTF8_STR));
byte messageDigest[] = algorithm.digest();
StringBuilder hexString = new StringBuilder();
for (int count = 0; count < messageDigest.length; count++) {
String hexaDecimal = Integer.toHexString(0xFF & messageDigest[count]);
while (hexaDecimal.length() < 2)
hexaDecimal = new StringBuilder(ZERO_STR).append(hexaDecimal).toString();
hexString.append(hexaDecimal);
}
result = hexString.toString();
} catch (NoSuchAlgorithmException e) {
} catch (UnsupportedEncodingException e) {
}
return result;
}
}
使用单例实例,实现了字符串的加密和解密,并且它们大部分都在工作。
有时,虽然密码已经初始化,但仍然抛出异常:java.lang.IllegalStateException: Cipher not initialized
该场景主要是在某个时间间隔(30 分钟)之后执行字符串解密。
会不会是单例实例使用不当造成的?
而不是 Singleton 类,我试图加密字符串,使用 new 运算符创建一个 Encryption 类的实例,但问题是我需要相同的对象进行解密,否则会java.lang.IllegalStateException: Cipher not initialized
被抛出。
欢迎任何建议/提示。