我正在编写一个从控制台输入的程序 - 一个zip文件的名称，一个包含从第一个zip生成的（de / en）加密文件的zip文件的名称和一个包含公钥的文件。我在解密时遇到异常：
exception Exception in thread "main" javax.crypto.BadPaddingException: Decryption error
at sun.security.rsa.RSAPadding.unpadV15(RSAPadding.java:380)
at sun.security.rsa.RSAPadding.unpad(RSAPadding.java:291)
at com.sun.crypto.provider.RSACipher.doFinal(RSACipher.java:363)
at com.sun.crypto.provider.RSACipher.engineDoFinal(RSACipher.java:389)
at javax.crypto.Cipher.doFinal(Cipher.java:2165)
at com.Main.decrypt(Main.java:67)
at com.Main.main(Main.java:201)
无法弄清楚为什么会出现此异常？
公钥：
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCE3pA746UfpC8sFk8ZJp0yupyJqj5jy6cjdxUYoP7mCm7c0mqQDeCcDNBYW2eSozCioPrH/9L+CDQEPLYakoem+jFnUKDH5+pru/0PJTJJF8Xh/ZT9eJlvsYBr1/qSfICf6RTs7kzwq9IuSZBw7/tfNEF9i0A8FVox6HOopXod1QIDAQAB
私钥：
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
该程序的代码如下。任何帮助都很受欢迎：）
package com;
import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.Enumeration;
import java.util.Scanner;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;
import javax.crypto.Cipher;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DERNull;
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
public class Main {
public final static int BUFFER_SIZE = 117;
public static void decrypt(String originalZipFileName, String newZipFileName, String privateKeyFileName) throws Exception {
byte[] buffer = new byte[128];
ZipFile originalZipFile = new ZipFile(originalZipFileName);
ZipOutputStream newZipFile = new ZipOutputStream(new FileOutputStream(newZipFileName));
Enumeration<? extends ZipEntry> zipEntries = originalZipFile.entries();
String privateKey = getKeyString(privateKeyFileName);
PrivateKey key = makePrivateKey(privateKey);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, key);
while(zipEntries.hasMoreElements()){
ZipEntry entry = zipEntries.nextElement();
ZipEntry copy = new ZipEntry(entry.getName());
newZipFile.putNextEntry(copy);
InputStream inputEntry = originalZipFile.getInputStream(entry);
while(inputEntry.read(buffer) != -1){
newZipFile.write(cipher.doFinal(buffer));
}
newZipFile.closeEntry();
inputEntry.close();
}
newZipFile.close();
originalZipFile.close();
}
public static void encrypt(String originalZipFileName, String newZipFileName, String publicKeyFileName) throws Exception{
byte[] buffer = new byte[BUFFER_SIZE];
ZipFile originalZipFile = new ZipFile(originalZipFileName);
ZipOutputStream newZipFile = new ZipOutputStream(new FileOutputStream(newZipFileName));
Enumeration<? extends ZipEntry> zipEntries = originalZipFile.entries();
String publicKey = getKeyString(publicKeyFileName);
PublicKey key = makePublicKey(publicKey);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, key);
while(zipEntries.hasMoreElements()){
ZipEntry entry = zipEntries.nextElement();
ZipEntry copy = new ZipEntry(entry.getName());
newZipFile.putNextEntry(copy);
InputStream inputEntry = originalZipFile.getInputStream(entry);
while(inputEntry.read(buffer) != -1){
newZipFile.write(cipher.doFinal(buffer));
}
newZipFile.closeEntry();
inputEntry.close();
}
newZipFile.close();
originalZipFile.close();
}
public static String getKeyString(String fileName){
String key = new String();
try {
BufferedReader buf = new BufferedReader(new FileReader(fileName));
key = buf.readLine();
} catch ( IOException e) {
e.printStackTrace();
}
return key.trim();
}
public static PublicKey makePublicKey(String stored) throws GeneralSecurityException {
byte[] data = Base64.getDecoder().decode(stored);
X509EncodedKeySpec spec = new X509EncodedKeySpec(data);
KeyFactory fact = KeyFactory.getInstance("RSA");
return fact.generatePublic(spec);
}
public static PrivateKey makePrivateKey(String stored) throws GeneralSecurityException, Exception {
/*byte[] data = Base64.getDecoder().decode(stored);
PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(data);
KeyFactory fact = KeyFactory.getInstance("RSA");
return fact.generatePrivate(spec);*/
byte[] data = Base64.getDecoder().decode(stored);
ASN1EncodableVector v = new ASN1EncodableVector();
v.add(new ASN1Integer(0));
ASN1EncodableVector v2 = new ASN1EncodableVector();
v2.add(new ASN1ObjectIdentifier(PKCSObjectIdentifiers.rsaEncryption.getId()));
v2.add(DERNull.INSTANCE);
v.add(new DERSequence(v2));
v.add(new DEROctetString(data));
ASN1Sequence seq = new DERSequence(v);
byte[] privKey = seq.getEncoded("DER");
PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(privKey);
KeyFactory fact = KeyFactory.getInstance("RSA");
PrivateKey key = fact.generatePrivate(spec);
return key;
}
public static void main(String[] args) throws Exception {
Scanner scan = new Scanner(System.in);
System.out.println("Enter type of operation:");
String line = scan.nextLine();
if(line.equals("encrypt")){
System.out.println("Enter name of original ZIP file:");
String originalZipFileName = scan.nextLine();
System.out.println("Enter name of new ZIP file:");
String newZipFileName = scan.nextLine();
System.out.println("Enter name of file containg public key:");
String publicKeyFileName = scan.nextLine();
encrypt(originalZipFileName, newZipFileName, publicKeyFileName);
}
if(line.equals("decrypt")){
System.out.println("Enter name of original ZIP file:");
String originalZipFileName = scan.nextLine();
System.out.println("Enter name of new ZIP file:");
String newZipFileName = scan.nextLine();
System.out.println("Enter name of file containg private key:");
String privateKeyFileName = scan.nextLine();
decrypt(originalZipFileName, newZipFileName, privateKeyFileName);
}
}
}
PS：更新了decrypt方法。仍然给出同样的错误。
public static void decrypt(String originalZipFileName, String newZipFileName, String privateKeyFileName) throws Exception {
byte[] buffer = new byte[128];
ZipFile originalZipFile = new ZipFile(originalZipFileName);
ZipOutputStream newZipFile = new ZipOutputStream(new FileOutputStream(newZipFileName));
Enumeration<? extends ZipEntry> zipEntries = originalZipFile.entries();
String privateKey = getKeyString(privateKeyFileName);
PrivateKey key = makePrivateKey(privateKey);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, key);
while(zipEntries.hasMoreElements()){
ZipEntry entry = zipEntries.nextElement();
ZipEntry copy = new ZipEntry(entry.getName());
newZipFile.putNextEntry(copy);
InputStream inputEntry = originalZipFile.getInputStream(entry);
while(inputEntry.read(buffer) != -1){
newZipFile.write(cipher.doFinal(buffer));
}
newZipFile.closeEntry();
inputEntry.close();
}
newZipFile.close();
originalZipFile.close();
}
答案 0 :(得分：8)
约瑟夫是对的。
使用默认参数创建密码时，默认为“RSA / ECB / PKCS1Padding”。如果您不喜欢令人讨厌的意外，您应该明确指定填充。因为其他安全提供程序可能具有不同的默认参而且您永远不会事先知道每个特定JRE的安全设置。
因此PKCS1填充为原始数据增加了11个字节，从117个字节增加到128个字节。您应该考虑到这些数字特定于1024位RSA密钥（这些密钥是安全的），并且对于更长的密钥将是不同的。由于您从文件加载密钥，请考虑检查其长度。
@Test
public void testPadding() throws Exception {
SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(1024, random);
KeyPair keyPair = keyGen.generateKeyPair();
/* constant 117 is a public key size - 11 */
byte[] plaintext = new byte[117];
random.nextBytes(plaintext);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, keyPair.getPublic());
byte[] ciphertext = cipher.doFinal(plaintext);
System.out.println(plaintext.length + " becomes " + ciphertext.length);
}
打印
117 becomes 128
最后，考虑使用AES而不是RSA进行文件加密。
因此，要解决此问题，您需要使用大小为公钥长度的缓冲区 - 加密的11（117）和解密的公钥大小（128）。
更改
outputFile.write(cipher.doFinal(buffer), 0, read);
到
outputFile.write(cipher.doFinal(buffer));
因为缓冲区读取是117个字节，而doFinal结果的大小是128个字节。
您还需要缓冲输入流。当您从文件中读取时，它有时会很慢，然后InputStream将读取比缓冲区可能包含的数据少的数据。通过使用BufferedInputStream，可确保在读取调用返回之前有足够的数据。但是，对于解密而言，拥有完整的数据块至关重要
InputStream inputEntry = new BufferedInputStream(originalZipFile.getInputStream(entry));
答案 1 :(得分：1)
while((read = inputEntry.read(buffer)) != -1){
outputFile.write(cipher.doFinal(buffer), 0, read);
}
你这里有问题。 read是读取的明文的大小，而不是密文。你应该完全删除第二个和第三个参数。
将密文写入中间文件也浪费时间和空间。只需将其直接写入zip流即可。
答案 2 :(得分：0)
解密方法的字节数组的长度应为256个字节，因为它是算法的默认输出大小（多余的字节将导致该长度）。将byte[] buffer = new byte[128];更改为byte[] buffer = new byte[256];。