java_AES加密解密文件以及字符串

捣鼓了两个星期的加密解密文件夹，一开始是用异或，后来觉得太简单换成了AES，结果一堆bug，上网查了很多，现在将这个最终的版本记录下来。已经在android 5.1系统上测试过，是可以的。

/**
* 初始化 AES Cipher
* @param sKey
* @param cipherMode
* @return
*/
public static Cipher initAESCipher (String sKey, int cipherMode) throws Exception {
//创建Key gen
KeyGenerator keyGenerator = null;
Cipher cipher = null;
keyGenerator = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance( "SHA1PRNG" ,"Crypto");
sr.setSeed(sKey.getBytes("UTF-8"));
keyGenerator.init(128,sr);
SecretKey secretKey = keyGenerator.generateKey();
byte[] codeFormat = secretKey.getEncoded();
SecretKeySpec key = new SecretKeySpec(codeFormat, "AES");
cipher = Cipher.getInstance("AES");
//初始化
cipher.init(cipherMode, key);

return cipher;
}

/**
* 对文件进行AES加密
* @param sourceFile
* @param fileType
* @param sKey
* @return
*/
public static File encryptFile(File sourceFile,String fileType, String sKey) throws Exception {
//新建临时加密文件
File encrypfile = null;
InputStream inputStream = null;
OutputStream outputStream = null;

inputStream = new FileInputStream(sourceFile);
encrypfile = new File(fileType);
outputStream = new FileOutputStream(encrypfile);
Cipher cipher = initAESCipher(sKey,Cipher.ENCRYPT_MODE);
//以加密流写入文件
CipherInputStream cipherInputStream = new CipherInputStream(inputStream, cipher);
byte[] cache = new byte[1024];
int nRead = 0;
while ((nRead = cipherInputStream.read(cache)) != -1) {
outputStream.write(cache, 0, nRead);
outputStream.flush();
}
cipherInputStream.close();

sourceFile.delete();

inputStream.close();

outputStream.close();
Log.d("MainActivity", "加密成功");
return encrypfile;
}

/**
* AES方式解密文件
* @param sourceFile
* @return
*/
public static File decryptFile(File sourceFile,String fileType,String sKey) throws Exception {
File decryptFile = null;
InputStream inputStream = null;
OutputStream outputStream = null;

decryptFile = new File(fileType);;
Cipher cipher = initAESCipher(sKey,Cipher.DECRYPT_MODE);
inputStream = new FileInputStream(sourceFile);
outputStream = new FileOutputStream(decryptFile);
CipherOutputStream cipherOutputStream = new CipherOutputStream(outputStream, cipher);
byte [] buffer = new byte [1024];
int r;
while ((r = inputStream.read(buffer)) >= 0) {
cipherOutputStream.write(buffer, 0, r);
}
cipherOutputStream.close();

sourceFile.delete();

inputStream.close();

outputStream.close();
Log.d("MainActivity", "解密成功" );
return decryptFile;
}

如果要加密解密文件夹，只需要遍历进行加密解密即可：

public static void encryptFolder(String strPath){
File dir = new File(strPath);
File[] files = dir.listFiles();
if (files != null){
for (int i=0; i<files.length;i++){
String fileName = files[i].getName();
if (files[i].isDirectory()){
encryptFolder(files[i].getAbsolutePath());
}else if(fileName.contains(".lock")){
//表明该文件已经加密过了，不需要再次加密
continue;
}else{
File file = new File(files[i].getAbsolutePath());
try {
encryptFile(file,files[i].getAbsolutePath()+".lock", constants.CryptConstant.PRIVATE_AES_KEY);
} catch (Exception e) {
e.printStackTrace();
Log.d("MainActivity","加密出错"+e.getMessage());
}
}
}
}
}

public static void decryptFolder(String strPath){
File dir = new File(strPath);
File[] files = dir.listFiles();
if (files != null){
for (int i=0; i<files.length;i++){
String fileName = files[i].getName();
if (files[i].isDirectory()){
decryptFolder(files[i].getAbsolutePath());
}else {
//只有是加密文件才进行解密
if (files[i].getAbsolutePath().contains(".lock")){
File file = new File(files[i].getAbsolutePath());
try {
decryptFile(file,files[i].getAbsolutePath().replace(".lock",""), constants.CryptConstant.PRIVATE_AES_KEY);
} catch (Exception e) {
e.printStackTrace();
Log.d("MainActivity", "解密出错" + e.getMessage());
}
}
}
}
}
}

加密解密字符串的代码如下：

/**
* 生成指定字符串的密钥
* @param secret        要生成密钥的字符串
* @return secretKey    生成后的密钥
* @throws GeneralSecurityException
*/
private static Key getKey(String secret) throws GeneralSecurityException {
KeyGenerator kgen = KeyGenerator.getInstance(type);

try {
SecureRandom sr = SecureRandom.getInstance( "SHA1PRNG" ,"Crypto");
sr.setSeed(secret.getBytes("UTF-8"));
kgen.init(128,sr);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
SecretKey secretKey = kgen.generateKey();
return secretKey;
}

public static String encryString(String privateKey,String content){
Key key = null;
try {
key = getKey(privateKey);
Cipher cipher = Cipher.getInstance(type + "/ECB/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] byteContent = content.getBytes("UTF-8");
byte[] result=cipher.doFinal(byteContent);
String s = Base64.encodeToString(result, Base64.DEFAULT);
return s;
} catch (GeneralSecurityException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return null;
}

public static String decryptString(String privateKey,String content){
Key key = null;
try {
key = getKey(privateKey);
Cipher cipher = Cipher.getInstance(type + "/ECB/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] decodeValue = Base64.decode(content, Base64.DEFAULT);
byte[] result=cipher.doFinal(decodeValue);
return new String(result,"UTF-8");
} catch (GeneralSecurityException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return null;
}