[英]Handling of IV and salt in Java encryption and decryption
所以我试图解密一个方法中的消息,但它不起作用,因为我需要做cipher.init(Cipher.ENCRYPT_MODE, secret)
然后我尝试将new IvParameterSpec(iv)
添加到cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
。 否则,它只返回一个NullPointerException我想知道是否可以在方法中执行此操作而不是一直写入它。 我真的不能想到一个解决方案,这就是为什么我在这里。 加密工作正常但不解密。
项目运行: JRE 7
加密代码:
public static String encrypt(String str) {
try {
SecureRandom random = new SecureRandom();
byte[] salt = new byte[16];
random.nextBytes(salt);
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(str.toCharArray(), salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secret); //<--- Need to do this before writing IvPerameterSpec,
// But I think that it's not possible if I have it in another method.
byte[] encryptedText = cipher.doFinal(str.getBytes("UTF-8"));
return new String(encryptedText);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
解密代码:
public static String decrypt(String str) {
try {
SecureRandom random = new SecureRandom();
byte[] salt = new byte[16];
random.nextBytes(salt);
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(str.toCharArray(), salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
AlgorithmParameters params = cipher.getParameters();
byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();
cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
// ^^^ Returns NullPointerException
byte[] ciphertext = cipher.doFinal(str.getBytes("UTF-8"));
String decryptedText = new String(cipher.doFinal(ciphertext), "UTF-8");
return new String(decryptedText);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
例外:
java.lang.NullPointerException
at me.Sansanvi.Encryption.api.ComputerAPI.decrypt(ComputerAPI.java:149)
at me.Sansanvi.Encryption.EncryptionMain.initializeFiles(EncryptionMain.java:46)
at me.Sansanvi.Encryption.EncryptionMain.<init>(EncryptionMain.java:36)
at me.Sansanvi.Encryption.EncryptionMain$1.run(EncryptionMain.java:23)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$200(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
我将方法更改为以下内容并且它们有效:
private static final String ALGORITHM = "AES";
public static byte[] encrypt(byte[] str) {
try {
SecretKeySpec secretKey = new SecretKeySpec("MZygpewJsCpRrfOr".getBytes(StandardCharsets.UTF_8), ALGORITHM);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
return cipher.doFinal(str);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public static byte[] decrypt(byte[] str) {
try {
SecretKeySpec secretKey = new SecretKeySpec("MZygpewJsCpRrfOr".getBytes(StandardCharsets.UTF_8), ALGORITHM);
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, secretKey);
return cipher.doFinal(str);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
我不再得到任何错误/异常,但是当我关闭我的应用程序时,我在控制台中得到了这个:
[0x7FFC837C7430] ANOMALY: use of REX.w is meaningless (default operand size is 64)
[0x7FFC837C7430] ANOMALY: use of REX.w is meaningless (default operand size is 64)
[0x7FFC837C7430] ANOMALY: use of REX.w is meaningless (default operand size is 64)
[0x7FFC837C7430] ANOMALY: use of REX.w is meaningless (default operand size is 64)
[0x7FFC837C7430] ANOMALY: use of REX.w is meaningless (default operand size is 64)
[0x7FFC837C7430] ANOMALY: use of REX.w is meaningless (default operand size is 64)
[0x7FFC837C7430] ANOMALY: use of REX.w is meaningless (default operand size is 64)
[0x7FFC837C7430] ANOMALY: use of REX.w is meaningless (default operand size is 64)
你至少有四个问题而且你只发现其中一个问题。
期间EN cryption和使用时,产生IV。 完全相同的IV需要德 cryption期间使用。 IV不应该是秘密的。 您可以简单地将其与密文一起发送/存储。 通常,IV存储在密文的前面并在解密之前切掉。
对于CBC模式,它只需要是不可预测的(读取:随机)。 对于CTR模式,它需要是唯一的(当使用相同的密钥时)。
随机盐需要以与IV完全相同的方式处理:它不是秘密的,可以写在密文之前。
String
不是二进制数据的容器。 当您使用new String(encryptedText)
,您可能会丢失一些不可打印的字节,这会破坏您的密文并使明文无法恢复。 您需要使用Base64或Hex编码之类的东西来将二进制数据表示为可打印文本。
如果加密某些东西,则需要两件事:明文和密码(用于密钥派生)。 解密过程中还需要两件事:密文和密码(密钥)。 您在加密期间使用相同的字符串值。 然后,密文会被破坏,使得在解密期间需要原始字符串值。 这将首先打败加密它的目的。 您的加密方法基本上是一个哈希函数。
感谢wittyameta指出这一点。
因此,生成的代码看起来类似于:
public static String encrypt(String str, String password) {
try {
SecureRandom random = new SecureRandom();
byte[] salt = new byte[16];
random.nextBytes(salt);
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secret);
AlgorithmParameters params = cipher.getParameters();
byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();
byte[] encryptedText = cipher.doFinal(str.getBytes("UTF-8"));
// concatenate salt + iv + ciphertext
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
outputStream.write(salt);
outputStream.write(iv);
outputStream.write(encryptedText);
// properly encode the complete ciphertext
return DatatypeConverter.printBase64Binary(outputStream.toByteArray());
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public static String decrypt(String str, String password) {
try {
byte[] ciphertext = DatatypeConverter.parseBase64Binary(str);
if (ciphertext.length < 48) {
return null;
}
byte[] salt = Arrays.copyOfRange(ciphertext, 0, 16);
byte[] iv = Arrays.copyOfRange(ciphertext, 16, 32);
byte[] ct = Arrays.copyOfRange(ciphertext, 32, ciphertext.length);
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
byte[] plaintext = cipher.doFinal(ct);
return new String(plaintext, "UTF-8");
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
我已经将它用于兼容Java 7的Base64编码/解码。
您没有正确初始化密码首先需要实例(您正确地执行此操作):
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
然后你需要初始化它有多个init方法:
public void init(int opmode, Key key);
public void init(int opmode, Certificate certificate);
public void init(int opmode, Key key, SecureRandom random);
public void init(int opmode, Certificate certificate,
SecureRandom random);
public void init(int opmode, Key key,
AlgorithmParameterSpec params);
public void init(int opmode, Key key,
AlgorithmParameterSpec params, SecureRandom random);
public void init(int opmode, Key key,
AlgorithmParameters params);
public void init(int opmode, Key key,
AlgorithmParameters params, SecureRandom random);
在你的情况下,你想使用这个:
public void init(int opmode, Key key,
AlgorithmParameterSpec params);
但是调用cipher.getParameters();
在init之前总是返回null。 有你的NullPointerException。
此外,代码中存在更多错误,例如使用数据加密作为密钥。
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