对于一个被问了很多次的问题，我很抱歉向您询问您的技能。 我有一个关于 RSA 加密的问题。 我已经检查过有关此问题的其他主题，但没有找到任何有用的答案。 我希望你能帮助我。
我想读取一个文件，加密其内容，然后解密它并将这些解密的字节放入一个新文件中。
我其实可以： - 获取文件的字节数 - 加密它
我有一个例外：javax.crypto.BadPaddingException：数据必须从零开始。
这是我的代码：
package com.bodom.ghosty;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import java.io.*;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.util.Scanner;
public class EncryptionUtil {
private final PrivateKey privateKey;
private final PublicKey publicKey;
/**
* Build an EncryptionUtil object
*
* @param keyPair The KeyPair used for Ghosty
*/
public EncryptionUtil (KeyPair keyPair) {
this.privateKey = keyPair.getPrivate();
this.publicKey = keyPair.getPublic();
}
/**
* Generate a pair of RSA keys
*
* @return A keypair of RSA keys
* @throws NoSuchAlgorithmException
*/
private static KeyPair keyGenerate() throws NoSuchAlgorithmException {
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(2048);
return keyGen.genKeyPair();
}
/**
* Crypt data
*
* @param data Data to encrypt
* @return The crypted data
* @throws NoSuchAlgorithmException
* @throws NoSuchPaddingException
* @throws InvalidKeyException
* @throws IllegalBlockSizeException
* @throws BadPaddingException
*/
private static byte[] rsaEncryption(byte[] data, EncryptionUtil encryptionUtil) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.ENCRYPT_MODE, encryptionUtil.publicKey);
return cipher.doFinal(data);
}
/**
* Read the bytes of a file
*
* @param file is the file to read
* @return the bytes of the file
* @throws IOException
*/
private static byte[] readBytesInFile (Path file) throws IOException {
byte[] result = new byte[(int)Files.size(file)];
try {
try (InputStream inputStream = new BufferedInputStream(new FileInputStream(file.getFileName().toString()))) {
int bytesRead = 0;
while (bytesRead < result.length) {
int bytesLeft = result.length - bytesRead;
int bytesGet = inputStream.read(result, bytesRead, bytesLeft);
if (bytesGet > 0) {
bytesRead += bytesGet;
}
}
}
} catch (IOException e) {
System.out.println(e);
}
return result;
}
/**
* Encrypt a file
*
* @param file Path of the file to crypt
* @return A byte array which contains the crypted lines of the file
* @throws java.io.IOException
* @throws javax.crypto.IllegalBlockSizeException
* @throws java.security.InvalidKeyException
* @throws javax.crypto.BadPaddingException
* @throws java.security.NoSuchAlgorithmException
* @throws javax.crypto.NoSuchPaddingException
*/
public static byte[] encryption (Path file, EncryptionUtil encryptionUtil) throws IOException, IllegalBlockSizeException, InvalidKeyException, BadPaddingException, NoSuchAlgorithmException, NoSuchPaddingException {
byte[] datatocrypt = readBytesInFile(file);
int offset = 0;
byte[] cryptedfile = null;
while (offset < datatocrypt.length) {
byte[] outputBytes;
byte[] tmp;
if(datatocrypt.length - offset < 200 ) {
outputBytes = new byte[datatocrypt.length - offset];
System.arraycopy(datatocrypt, offset, outputBytes, 0, datatocrypt.length - offset);
byte[] crypt = rsaEncryption(outputBytes, encryptionUtil);
tmp = cryptedfile;
if (tmp != null) {
cryptedfile = new byte[tmp.length + crypt.length];
}
else cryptedfile = new byte[crypt.length];
if (tmp != null) {
System.arraycopy(tmp, 0, cryptedfile, 0, tmp.length);
System.arraycopy(crypt, 0, cryptedfile, tmp.length, crypt.length);
}
else {
System.arraycopy(crypt, 0, cryptedfile, 0, crypt.length);
}
break;
}
outputBytes = new byte[200];
System.arraycopy(datatocrypt, offset, outputBytes, 0, 200);
byte[] crypt = rsaEncryption(outputBytes, encryptionUtil);
tmp = cryptedfile;
if (tmp != null) {
cryptedfile = new byte[tmp.length + crypt.length];
}
else cryptedfile = new byte[crypt.length];
if (tmp != null) {
System.arraycopy(tmp, 0, cryptedfile, 0, tmp.length);
System.arraycopy(crypt, 0, cryptedfile, tmp.length, crypt.length);
}
else {
System.arraycopy(crypt, 0, cryptedfile, 0, crypt.length);
}
offset += 200 ;
}
return cryptedfile;
}
/**
* Decrypt data
*
* @param crypteddata Crypted data to decrypt
* @return The decrypted data
* @throws NoSuchAlgorithmException
* @throws NoSuchPaddingException
* @throws InvalidKeyException
* @throws IllegalBlockSizeException
* @throws BadPaddingException
*/
private static byte[] rsaDecryption(byte[] crypteddata, EncryptionUtil encryptionUtil) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.DECRYPT_MODE, encryptionUtil.privateKey);
return cipher.doFinal(crypteddata);
}
/**
* Decrypt a file
*
* @param file Path of the file to decrypt
* @return A byte array which contains the decrypted lines of the file
* @throws IOException
* @throws IllegalBlockSizeException
* @throws InvalidKeyException
* @throws BadPaddingException
* @throws NoSuchAlgorithmException
* @throws NoSuchPaddingException
*/
public static byte[] decryption(Path file, EncryptionUtil encryptionUtil) throws IllegalBlockSizeException, InvalidKeyException, BadPaddingException, NoSuchAlgorithmException, NoSuchPaddingException, IOException {
byte[] crypteddata = readBytesInFile(file);
int offset = 0;
byte[] decryptedfile = null;
while (offset < crypteddata.length) {
byte[] outputBytes;
byte[] tmp;
if(crypteddata.length - offset < 200 ) {
outputBytes = new byte[crypteddata.length - offset];
System.arraycopy(crypteddata, offset, outputBytes, 0, crypteddata.length - offset);
byte[] decrypt = rsaDecryption(outputBytes, encryptionUtil);
tmp = decryptedfile;
if (tmp != null) {
decryptedfile = new byte[tmp.length + decrypt.length];
}
else decryptedfile = new byte[decrypt.length];
if (tmp != null) {
System.arraycopy(tmp, 0, decryptedfile, 0, tmp.length);
System.arraycopy(decrypt, 0, decryptedfile, tmp.length, decrypt.length);
}
else {
System.arraycopy(decrypt, 0, decryptedfile, 0, decrypt.length);
}
break;
}
outputBytes = new byte[200];
System.arraycopy(crypteddata, offset, outputBytes, 0, 200);
byte[] decrypt = rsaDecryption(outputBytes, encryptionUtil);
tmp = decryptedfile;
if (tmp != null) {
decryptedfile = new byte[decrypt.length + tmp.length];
}
else decryptedfile = new byte[decrypt.length];
if (tmp != null) {
System.arraycopy(tmp, 0, decryptedfile, 0, tmp.length);
System.arraycopy(decrypt, 0, decryptedfile, tmp.length, decrypt.length);
}
else {
System.arraycopy(decrypt, 0, decryptedfile, 0, decrypt.length);
}
offset +=200 ;
}
return decryptedfile;
}
/**
* Save a key in a file
*
* @param modulus Modulus of the key to save
* @param exponent Exponent of the key to save
* @param filename File used to save the keys
* @throws IOException
* @throws NoSuchAlgorithmException
*/
private static void saveKeyToFile (BigInteger modulus, BigInteger exponent, String filename) throws IOException, NoSuchAlgorithmException {
Path path = Paths.get(filename);
if(!Files.exists(path)) {
Files.createFile(path);
}
try (ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream(filename))) {
objectOutputStream.writeObject(modulus);
objectOutputStream.writeObject(exponent);
}
}
/**
* Save a KeyPair in two files
*
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
* @throws FileNotFoundException
* @throws IOException
*/
public static void saveKeyPair(EncryptionUtil encryptionUtil, String directorypath) throws NoSuchAlgorithmException, InvalidKeySpecException, IOException {
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPublicKeySpec rsaPublicKeySpec = keyFactory.getKeySpec(encryptionUtil.publicKey, RSAPublicKeySpec.class);
saveKeyToFile(rsaPublicKeySpec.getModulus(), rsaPublicKeySpec.getPublicExponent(), directorypath + "/public.key");
RSAPrivateKeySpec rsaPrivateKeySpec = keyFactory.getKeySpec(encryptionUtil.privateKey, RSAPrivateKeySpec.class);
saveKeyToFile(rsaPrivateKeySpec.getModulus(), rsaPrivateKeySpec.getPrivateExponent(), directorypath + "/private.key");
}
/**
* Get a PublicKey from a file
*
* @param filename File where the PublicKey is saved
* @return The PublicKey get in the file
* @throws IOException
* @throws ClassNotFoundException
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
*/
private static PublicKey getPublicKeyFromFile (String filename) throws IOException, ClassNotFoundException, NoSuchAlgorithmException, InvalidKeySpecException {
try (ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream(filename))) {
BigInteger modulus = (BigInteger) objectInputStream.readObject();
BigInteger exponent = (BigInteger) objectInputStream.readObject();
RSAPublicKeySpec rsaPublicKeySpec = new RSAPublicKeySpec(modulus, exponent);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
return keyFactory.generatePublic(rsaPublicKeySpec);
}
}
/**
* Get a PrivateKey from a file
*
* @param filename File where the PrivateKey is saved
* @return The PrivateKey get in the file
* @throws IOException
* @throws ClassNotFoundException
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
*/
private static PrivateKey getPrivateKeyFromFile (String filename) throws IOException, ClassNotFoundException, NoSuchAlgorithmException, InvalidKeySpecException {
try (ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream(filename))) {
BigInteger modulus = (BigInteger) objectInputStream.readObject();
BigInteger exponent = (BigInteger) objectInputStream.readObject();
RSAPrivateKeySpec rsaPrivateKeySpec = new RSAPrivateKeySpec(modulus, exponent);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
return keyFactory.generatePrivate(rsaPrivateKeySpec);
}
}
/**
* Get the RSA keypair from the files
*
* @return The Keypair which contains the public and the private key
* @throws IOException
* @throws ClassNotFoundException
* @throws NoSuchAlgorithmException
* @throws InvalidKeySpecException
*/
public static KeyPair getKeysFromFiles (String directorypath) throws IOException, ClassNotFoundException, NoSuchAlgorithmException, InvalidKeySpecException{
PublicKey publicKey = getPublicKeyFromFile(directorypath + "/public.key");
PrivateKey privateKey = getPrivateKeyFromFile(directorypath + "/private.key");
return new KeyPair(publicKey, privateKey);
}
public static void main(String[] args) {
EncryptionUtil encryptionUtil = null;
Scanner scanner = new Scanner(System.in);
System.out.println("Path of the keys :");
String path = scanner.nextLine();
try {
encryptionUtil = new EncryptionUtil(EncryptionUtil.keyGenerate());
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
Path directorypath = Paths.get(path);
try {
Files.createDirectories(directorypath);
} catch (IOException e) {
e.printStackTrace();
}
try {
saveKeyPair(encryptionUtil, path);
} catch (NoSuchAlgorithmException | InvalidKeySpecException| IOException e) {
System.out.println("Error during the storage of the keys : " + e);
}
// Crypt part
byte[] uncrypt;
try {
if (encryptionUtil != null) {
if (encryptionUtil.publicKey != null && encryptionUtil.privateKey != null) {
//Cryptage
byte[] crypt = encryption(Paths.get("filetocrypt"), encryptionUtil);
FileOutputStream fileOutputStream = new FileOutputStream("cryptedfile");
FileChannel channel = fileOutputStream.getChannel();
ByteBuffer byteBuffer = ByteBuffer.allocate(crypt.length * 2);
byteBuffer.put(crypt);
byteBuffer.flip();
channel.write(byteBuffer);
channel.close();
//Decryptage
uncrypt = decryption(Paths.get("cryptedfile"), encryptionUtil);
String v = new String(uncrypt);
System.out.println("END " + v);
}
}
} catch (InvalidKeyException | NoSuchAlgorithmException
| NoSuchPaddingException | IllegalBlockSizeException
| BadPaddingException | IOException e) {
e.printStackTrace();
}
}
}
我读到，当使用错误的私钥进行解密或密码被滥用时，经常会出现这个问题。 但我不认为这里是这样，或者我没有看到...... 我不知道我的代码有什么问题。 要运行此代码，您需要一个名为“filetocrypt”的文件。 我使用 bytes[] 并将它们拆分来加密和解密文件，以避免 RSA 的字节大小问题。这种分割效果很好（我尝试使用字符串文件而不使用 RSA 算法）
感谢您的帮助！
您的解密代码需要与加密代码不同。有很多问题，但导致错误的问题如下。由于 RSA 填充，您的输入块为 200 字节，输出块为 256 字节。因此，解密时，您需要一次读取 256 个字节，并期望获得 200 个字节。相反，您一次只能读取 200 个字节。
import java.security.*;
import java.security.interfaces.*;
import javax.crypto.Cipher;
public class RsaToy {
public static void main(String[] args) throws Exception {
KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
kpg.initialize(1024);
KeyPair kp = kpg.generateKeyPair();
RSAPublicKey pub = (RSAPublicKey) kp.getPublic();
RSAPrivateKey priv = (RSAPrivateKey) kp.getPrivate();
Cipher c = Cipher.getInstance("RSA/ECB/PKCS1PADDING");
c.init(Cipher.ENCRYPT_MODE, pub);
byte [] plain = new byte[100]; // initialize to all zero bytes
// First encrypt: length of input (plain) is 100
byte [] cipher = c.doFinal(plain);
System.out.println("length of cipher is " + cipher.length);
// Now decrypt: length of input(cipher) is 128;
c.init(Cipher.DECRYPT_MODE, priv);
byte [] decrypted_cipher = c.doFinal(cipher);
System.out.println("length of decrypted cipher is " + decrypted_cipher.length);
}
}
那么，在你的解密方法中，改变3中出现的200??到 256。你真的不应该对这些常量进行硬编码。
尝试使用“NoPadding”：
Cipher cipher = Cipher.getInstance("RSA/ECB/NoPadding");