我正在尝试制定使用“PBEWithHmacSHA256AndAES_256”标准加密和解密文件的正确过程。
据我了解,example code来自甲骨文。
我已经收集到需要盐,以及迭代计数和哈希标准。
所以我有我的主要方法,传递给加密方法:
new String(key).toCharArray()
作为字节数组(使用此方法进行其他加密运行)initVector
作为字节数组inputFile
作为字符串 outputFile
作为字符串 我已经按照代码示例编写了我认为对加密方法正确的代码。我通过将它们都附加到密文来存储要用于解密的盐和IV。
private static void encrypt(byte[] key, byte[] initVector, String inputFile, String outputFile) //exceptions for throws... {
//Initalisation for encryption
Cipher cipher;
byte[] salt = new byte[16];
SecureRandom rand = new SecureRandom();
// Salt randomly generated with base64
rand.nextBytes(salt);
System.out.println("my salt should be" + Base64.getEncoder().encodeToString(salt));
salt = Base64.getEncoder().encode(salt);
// Iteration count
int count = 1000;
IvParameterSpec iv = new IvParameterSpec(initVector);
// Create PBE parameter set
PBEParameterSpec pbeParamSpec = new PBEParameterSpec(Base64.getDecoder().decode(salt), count, iv);
// Convert pass into SecretKey object
PBEKeySpec pbeKeySpec = new PBEKeySpec(new String(key).toCharArray());
SecretKeyFactory keyFac = SecretKeyFactory.getInstance("PBEWithHmacSHA256AndAES_256");
SecretKey pbeKey;
try {
pbeKey = keyFac.generateSecret(pbeKeySpec);
} catch (InvalidKeySpecException e) {
System.out.println("Sorry, the password specified cannot be used as a secret key");
System.out.println("Please check that your password uses valid characters");
return;
}
// Create PBE Cipher
cipher = Cipher.getInstance("PBEWithHmacSHA256AndAES_256");
// Initialize PBE Cipher with key and parameters
cipher.init(Cipher.ENCRYPT_MODE, pbeKey, pbeParamSpec);
}
//File error checking and file handling (i.e. generating file paths)...
System.out.println("Secret key is " + Base64.getEncoder().encodeToString(key));
System.out.println("IV is " + Base64.getEncoder().encodeToString(initVector));
//Special file reading and writing with 'Cipher Stream'
try (InputStream fin = FileEncryptor.class.getResourceAsStream(loadFile.getName());
OutputStream fout = Files.newOutputStream(saveFile);
CipherOutputStream cipherOut = new CipherOutputStream(fout, cipher) {
}) {
final byte[] bytes = new byte[1024];
for(int length=fin.read(bytes); length!=-1; length = fin.read(bytes)){
fout.write(initVector);
fout.write(salt);
cipherOut.write(bytes, 0, length);
}
} catch (IOException e) {
System.out.println("Something went wrong with reading and writing these files!");
System.out.println("Please check you have the latest version of this program");
System.out.println("Contact your IT admin to make sure you have sufficient privileges");
}
System.out.println("SUCCESS! Encryption finished, saved at specified location");
}
然后我也有我的main方法,传入解密方法:String inputKEY
作为字符串(也将此方法用于其他加密运行)inputIV
的字符串, 已作为 null 传入,因为不用于 PBE。inputFile
作为字符串outputFile
作为字符串私有(private)静态无效解密(字符串输入 key ,字符串输入IV,字符串输入文件,字符串输出文件){
密码密码=空;
//File error checking and file handling (i.e. generating file paths)...
InputStream encryptedData = Files.newInputStream(loadFilePath);
PBEKeySpec pbeKeySpec = new PBEKeySpec(inputKEY.toCharArray());
SecretKeyFactory keyFac = SecretKeyFactory.getInstance("PBEWithHmacSHA256AndAES_256");
SecretKey pbeKey = null;
try {
pbeKey = keyFac.generateSecret(pbeKeySpec);
} catch (InvalidKeySpecException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
byte[] initVect = new byte[16];
encryptedData.read(initVect);
IvParameterSpec iv = new IvParameterSpec(Base64.getDecoder().decode(initVect);
byte[] salt = new byte[16];
encryptedData.read(salt);
PBEParameterSpec pbeParamSpec = new PBEParameterSpec(Base64.getDecoder().decode(salt), 1000, iv);
cipher = Cipher.getInstance("PBEWithHmacSHA256AndAES_256");
System.out.println("my salt should be" + Base64.getEncoder().encodeToString(Base64.getDecoder().decode(salt)));
cipher.init(Cipher.DECRYPT_MODE, pbeKey, pbeParamSpec);
try (CipherInputStream decryptStream = new CipherInputStream(encryptedData, cipher);
OutputStream decryptedOut = Files.newOutputStream(saveFile)){
final byte[] bytes = new byte[1024];
for(int length=decryptStream.read(bytes); length!=-1; length = decryptStream.read(bytes)){
decryptedOut.write(bytes, 0, length);
}
} catch (IOException e) { //This is caught when decryption is run
System.out.println("Something went wrong with reading and writing these files!");
System.out.println("Please check you have the latest version of this program");
System.out.println("Contact your IT admin to make sure you have sufficient privileges");
}
System.out.println("SUCESS! Decryption finished, saved at specified location");
}我相信我对 PBE 的理解有些不对劲,因此我实现它的方式可能是错误的。谁能指出似乎有什么问题?
最佳答案
主要问题是:
for
中。环形。 encrypt
不是 Base64 编码,而是在 decrypt
中进行 Base64 解码. encrypt
(不必要)Base64 编码,即存储 24 个字节。在 decrypt
但是只加载了 16 个字节。 还:
encrypt
和 decrypt
对 key 和 IV 使用不同的参数类型。 注意:与您的代码相比,linked除了 key 之外,代码还确定来自密码和盐的 IV。
在您的代码中,IV 被传递。因此,您必须确保 key /IV 对只能使用一次。通常为每个加密生成一个随机 IV。
在以下代码中(基于您的代码,但为了简单起见,没有异常处理)这些问题已得到修复/优化。此外,该代码适用
FileInputStream
和 FileOutputStream
而不是你的类(class)(但这不是必需的):private static void encrypt(String key, byte[] initVector, String inputFile, String outputFile) throws Exception {
// Key
PBEKeySpec pbeKeySpec = new PBEKeySpec(key.toCharArray());
SecretKeyFactory keyFac = SecretKeyFactory.getInstance("PBEWithHmacSHA256AndAES_256");
SecretKey pbeKey = keyFac.generateSecret(pbeKeySpec);
// IV
IvParameterSpec iv = new IvParameterSpec(initVector);
// Salt
SecureRandom rand = new SecureRandom();
byte[] salt = new byte[16];
rand.nextBytes(salt);
// ParameterSpec
int count = 1000; // should be larger, see Michael Fehr's comment
PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, count, iv);
// Cipher
Cipher cipher = Cipher.getInstance("PBEWithHmacSHA256AndAES_256");
cipher.init(Cipher.ENCRYPT_MODE, pbeKey, pbeParamSpec);
try (FileInputStream fin = new FileInputStream(inputFile);
FileOutputStream fout = new FileOutputStream(outputFile);
CipherOutputStream cipherOut = new CipherOutputStream(fout, cipher)) {
// Write IV, Salt
fout.write(initVector);
fout.write(salt);
// Encrypt
final byte[] bytes = new byte[1024];
for (int length = fin.read(bytes); length != -1; length = fin.read(bytes)) {
cipherOut.write(bytes, 0, length);
}
}
}
private static void decrypt(String key, byte[] initVect, String inputFile, String outputFile) throws Exception {
try (FileInputStream encryptedData = new FileInputStream(inputFile);
FileOutputStream decryptedOut = new FileOutputStream(outputFile)) {
// Key
PBEKeySpec pbeKeySpec = new PBEKeySpec(key.toCharArray());
SecretKeyFactory keyFac = SecretKeyFactory.getInstance("PBEWithHmacSHA256AndAES_256");
SecretKey pbeKey = keyFac.generateSecret(pbeKeySpec);
// Read IV
if (initVect == null) {
initVect = encryptedData.readNBytes(16);
}
IvParameterSpec iv = new IvParameterSpec(initVect);
// Read salt
byte[] salt = encryptedData.readNBytes(16);
// ParameterSpec
int count = 1000;
PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, count, iv);
// Cipher
Cipher cipher = Cipher.getInstance("PBEWithHmacSHA256AndAES_256");
cipher.init(Cipher.DECRYPT_MODE, pbeKey, pbeParamSpec);
try (CipherInputStream decryptStream = new CipherInputStream(encryptedData, cipher)) {
// Decrypt
final byte[] bytes = new byte[1024];
for (int length = decryptStream.read(bytes); length != -1; length = decryptStream.read(bytes)) {
decryptedOut.write(bytes, 0, length);
}
}
}
}
编辑 - 关于 decrypt
中盐和 IV 的读数:正如 GPI 在他们的评论中指出的那样, FileInputStream.read(byte[] b)
一般为 b.length
字节,但这不能保证。更鲁棒的是判断读取数据的长度,循环调用方法,直到数据完成。另一种选择是使用 InputStream.readNBytes(int len)
, 保证为 len
字节(除非遇到流结束或抛出异常),正如 Zabuzard 所建议的那样。在代码中,现在使用后者,即 read
已替换为 readNBytes
.
关于java - 如何使用从密码派生的 key 正确加密和解密文件,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/63717001/