使用带有 128 位密钥的 AES 和 PBKDF2 的 Java 密码体系结构进行文件加密
File Encryption with the Java Cryptography Architecture using AES with a 128-bit key and PBKDF2
我在解密文件时遇到此错误
我正在使用 PBKDF2 将密码短语转换为密钥，然后使用它。加密工作正常，但是当我尝试解密同一个文件时，出现以下错误。除了最后几行（可能是填充区域）外，解密文件给出了正确的数据。我通过在加密和解密时输出IV和密钥来调试它，它们都是相同的，但错误仍然存在。
public class FileEncryptorSkeleton{
private static final String progName = "FileEncryptor";
private static final int bufSize = 128;
/**
* @param args
*/
public static void main(String[] args) throws UnsupportedEncodingException {
BufferedInputStream in = null; // A buffered input stream to read from
BufferedOutputStream out = null; // And a buffered output stream to write to
SecretKeyFactory kf = null; // Something to create a key for us
KeySpec ks = null; // This is how we specify what kind of key we want it to generate
byte[] salt = new byte[20]; // Some salt for use with PBKDF2, only not very salty
SecretKey key = null; // The key that it generates
Cipher cipher = null; // The cipher that will do the real work
SecretKeySpec keyspec = null; // How we pass the key to the Cipher
int bytesRead = 0; // Number of bytes read into the input file buffer
byte[] iv = new byte[16];
// First, check the user has provided all the required arguments, and if they haven't, tell them then exit
if(args.length != 4) {
printUsageMessage(); System.exit(1);
}
// Open the input file
try {
in = new BufferedInputStream(new FileInputStream(args[1]));
} catch (FileNotFoundException e) {
printErrorMessage("Unable to open input file: " + args[1], null);
System.exit(1);
}
// And then the output file
try {
out = new BufferedOutputStream(new FileOutputStream(args[2]));
} catch (FileNotFoundException e) {
printErrorMessage("Unable to open output file: " + args[2], e);
System.exit(1);
}
try {
kf = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
} catch (NoSuchAlgorithmException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
}
// Set up a KeySpec for password-based key generation of a 128-bit key
ks = new PBEKeySpec(args[3].toCharArray(), salt, 1000, 128);
// Now run the passphrase through PBKDF2 to get the key
try {
key = kf.generateSecret(ks);
}catch(InvalidKeySpecException e){
System.exit(1);
}
// Get the byte encoded key value as a byte array
byte[] aeskey = key.getEncoded();
// Now generate a Cipher object for AES encryption in ECBC mode with PKCS #5 padding
// Use ECB for the first task, then switch to CBC for versions 2 and 3
try {
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
} catch (NoSuchAlgorithmException e) {
printErrorMessage("No Such Algorithm Exception when creating main cipher", e);
System.exit(2);
} catch (NoSuchPaddingException e) {
printErrorMessage("No Such Padding Exception when creating main cipher",e);
System.exit(2);
}
// Set a variable to indicate whether we're in encrypt or decrypt mode, based upon args[0]
int cipherMode = -1;
char mode = Character.toLowerCase(args[0].charAt(0));
switch (mode) {
case 'e' : cipherMode = Cipher.ENCRYPT_MODE; break;
case 'd' : cipherMode = Cipher.DECRYPT_MODE; break;
default: printUsageMessage(); System.exit(1);
}
// Set up a secret key specification, based on the 16-byte (128-bit) AES key array previously generated
keyspec = new SecretKeySpec(aeskey, "AES");
IvParameterSpec ivspec = new IvParameterSpec(iv);
// Now initialize the cipher in the right mode, with the keyspec and the ivspec
try {
cipher.init(cipherMode, keyspec,ivspec);
} catch (InvalidKeyException e) {
printErrorMessage("Invalid Key Spec",e); System.exit(2);
} catch (InvalidAlgorithmParameterException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
}
// Set up some input and output byte array buffers
byte[] inputBuffer = new byte[bufSize];
byte[] outputBuffer = null;
// "Prime the pump" - we've got to read something before we can encrypt it
// and not encrypt anything if we read nothing.
try {
bytesRead = in.read(inputBuffer);
} catch (IOException e) {
printErrorMessage("Error reading input file " + args[1],e); System.exit(1);
}
// As long as we've read something, loop around encrypting, writing and reading
// bytesRead will be zero if nothing was read, or -1 on EOF - treat them both the same
while (bytesRead > 0) {
// Now encrypt this block
outputBuffer = cipher.update(inputBuffer.toString().getBytes("UTF-8"));
// Write the generated block to file
try {
out.write(outputBuffer);
} catch (IOException e) {
printErrorMessage("Error writing to output file " + args[2],e); System.exit(1);
}
// And read in the next block of the file
try {
bytesRead = in.read(inputBuffer);
} catch (IOException e) {
printErrorMessage("Error reading input file " + args[1],e); System.exit(1);
}
}
try {
// Now do the final processing
outputBuffer =cipher.doFinal(inputBuffer.toString().getBytes("UTF-8"));
cipher.init(cipherMode, keyspec,ivspec);
System.out.println(ivspec+" "+cipherMode+" "+keyspec);
} catch (IllegalBlockSizeException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
} catch (BadPaddingException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
} catch (InvalidKeyException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
} catch (InvalidAlgorithmParameterException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
}
// Write the final block of output
try {
out.write(outputBuffer);
} catch (IOException e) {
printErrorMessage("Error on final write to output file " + args[2],e); System.exit(1);
}
// Close the output files
try {
in.close();
out.close();
} catch (IOException e) {
printErrorMessage("Error closing file", e);
}
// If we were continuing beyond this point, we should really overwrite key material, drop KeySpecs, etc.
}
/**
* Print an error message on , optionally picking up additional detail from
* a passed exception
* @param errMsg
* @param e
*/
private static void printErrorMessage(String errMsg, Exception e) {
System.err.println(errMsg);
if (e != null)
System.err.println(e.getMessage());
}
/**
* Print a usage message
*/
private static void printUsageMessage() {
System.out.println(progName + " $Revision: 1.1 $: Usage: " + progName + " E/D infile outfile passphrase");
}
}
Oct 18, 2019 11:27:46 PM FileEncryptorSkeleton main
SEVERE: null
javax.crypto.BadPaddingException: Given final block not properly padded. Such issues can arise if a bad key is used during decryption.
at com.sun.crypto.provider.CipherCore.unpad(CipherCore.java:975)
at com.sun.crypto.provider.CipherCore.fillOutputBuffer(CipherCore.java:1056)
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:853)
at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:446)
at javax.crypto.Cipher.doFinal(Cipher.java:2164)
at FileEncryptorSkeleton.main(FileEncryptorSkeleton.java:174)
Cipher#update-和Cipher#doFinal-方法都使用inputBuffer.toString()，它只包含对象的名称class和哈希码，而不是实际数据缓冲区。
从 inputBuffer-byte[] 中读取前 bytesRead 个字节（之前从 in-BufferedInputStream 中读取）并处理它们 (Cipher#update) 是正确的：
outputBuffer = cipher.update(inputBuffer, 0, bytesRead);
包含 cipher#update 调用的循环仅在没有字节被读取到 inputBuffer-byte[] 时才会保留，因此最终处理适用 (Cipher#doFinal):
outputBuffer = cipher.doFinal();
此外，在 cipher#doFinal 调用之后的第二个 cipher#init 调用是不必要的 (Cipher#init)。
我在解密文件时遇到此错误
我正在使用 PBKDF2 将密码短语转换为密钥，然后使用它。加密工作正常，但是当我尝试解密同一个文件时，出现以下错误。除了最后几行（可能是填充区域）外，解密文件给出了正确的数据。我通过在加密和解密时输出IV和密钥来调试它，它们都是相同的，但错误仍然存在。
public class FileEncryptorSkeleton{
private static final String progName = "FileEncryptor";
private static final int bufSize = 128;
/**
* @param args
*/
public static void main(String[] args) throws UnsupportedEncodingException {
BufferedInputStream in = null; // A buffered input stream to read from
BufferedOutputStream out = null; // And a buffered output stream to write to
SecretKeyFactory kf = null; // Something to create a key for us
KeySpec ks = null; // This is how we specify what kind of key we want it to generate
byte[] salt = new byte[20]; // Some salt for use with PBKDF2, only not very salty
SecretKey key = null; // The key that it generates
Cipher cipher = null; // The cipher that will do the real work
SecretKeySpec keyspec = null; // How we pass the key to the Cipher
int bytesRead = 0; // Number of bytes read into the input file buffer
byte[] iv = new byte[16];
// First, check the user has provided all the required arguments, and if they haven't, tell them then exit
if(args.length != 4) {
printUsageMessage(); System.exit(1);
}
// Open the input file
try {
in = new BufferedInputStream(new FileInputStream(args[1]));
} catch (FileNotFoundException e) {
printErrorMessage("Unable to open input file: " + args[1], null);
System.exit(1);
}
// And then the output file
try {
out = new BufferedOutputStream(new FileOutputStream(args[2]));
} catch (FileNotFoundException e) {
printErrorMessage("Unable to open output file: " + args[2], e);
System.exit(1);
}
try {
kf = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
} catch (NoSuchAlgorithmException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
}
// Set up a KeySpec for password-based key generation of a 128-bit key
ks = new PBEKeySpec(args[3].toCharArray(), salt, 1000, 128);
// Now run the passphrase through PBKDF2 to get the key
try {
key = kf.generateSecret(ks);
}catch(InvalidKeySpecException e){
System.exit(1);
}
// Get the byte encoded key value as a byte array
byte[] aeskey = key.getEncoded();
// Now generate a Cipher object for AES encryption in ECBC mode with PKCS #5 padding
// Use ECB for the first task, then switch to CBC for versions 2 and 3
try {
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
} catch (NoSuchAlgorithmException e) {
printErrorMessage("No Such Algorithm Exception when creating main cipher", e);
System.exit(2);
} catch (NoSuchPaddingException e) {
printErrorMessage("No Such Padding Exception when creating main cipher",e);
System.exit(2);
}
// Set a variable to indicate whether we're in encrypt or decrypt mode, based upon args[0]
int cipherMode = -1;
char mode = Character.toLowerCase(args[0].charAt(0));
switch (mode) {
case 'e' : cipherMode = Cipher.ENCRYPT_MODE; break;
case 'd' : cipherMode = Cipher.DECRYPT_MODE; break;
default: printUsageMessage(); System.exit(1);
}
// Set up a secret key specification, based on the 16-byte (128-bit) AES key array previously generated
keyspec = new SecretKeySpec(aeskey, "AES");
IvParameterSpec ivspec = new IvParameterSpec(iv);
// Now initialize the cipher in the right mode, with the keyspec and the ivspec
try {
cipher.init(cipherMode, keyspec,ivspec);
} catch (InvalidKeyException e) {
printErrorMessage("Invalid Key Spec",e); System.exit(2);
} catch (InvalidAlgorithmParameterException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
}
// Set up some input and output byte array buffers
byte[] inputBuffer = new byte[bufSize];
byte[] outputBuffer = null;
// "Prime the pump" - we've got to read something before we can encrypt it
// and not encrypt anything if we read nothing.
try {
bytesRead = in.read(inputBuffer);
} catch (IOException e) {
printErrorMessage("Error reading input file " + args[1],e); System.exit(1);
}
// As long as we've read something, loop around encrypting, writing and reading
// bytesRead will be zero if nothing was read, or -1 on EOF - treat them both the same
while (bytesRead > 0) {
// Now encrypt this block
outputBuffer = cipher.update(inputBuffer.toString().getBytes("UTF-8"));
// Write the generated block to file
try {
out.write(outputBuffer);
} catch (IOException e) {
printErrorMessage("Error writing to output file " + args[2],e); System.exit(1);
}
// And read in the next block of the file
try {
bytesRead = in.read(inputBuffer);
} catch (IOException e) {
printErrorMessage("Error reading input file " + args[1],e); System.exit(1);
}
}
try {
// Now do the final processing
outputBuffer =cipher.doFinal(inputBuffer.toString().getBytes("UTF-8"));
cipher.init(cipherMode, keyspec,ivspec);
System.out.println(ivspec+" "+cipherMode+" "+keyspec);
} catch (IllegalBlockSizeException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
} catch (BadPaddingException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
} catch (InvalidKeyException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
} catch (InvalidAlgorithmParameterException ex) {
Logger.getLogger(FileEncryptorSkeleton.class.getName()).log(Level.SEVERE, null, ex);
}
// Write the final block of output
try {
out.write(outputBuffer);
} catch (IOException e) {
printErrorMessage("Error on final write to output file " + args[2],e); System.exit(1);
}
// Close the output files
try {
in.close();
out.close();
} catch (IOException e) {
printErrorMessage("Error closing file", e);
}
// If we were continuing beyond this point, we should really overwrite key material, drop KeySpecs, etc.
}
/**
* Print an error message on , optionally picking up additional detail from
* a passed exception
* @param errMsg
* @param e
*/
private static void printErrorMessage(String errMsg, Exception e) {
System.err.println(errMsg);
if (e != null)
System.err.println(e.getMessage());
}
/**
* Print a usage message
*/
private static void printUsageMessage() {
System.out.println(progName + " $Revision: 1.1 $: Usage: " + progName + " E/D infile outfile passphrase");
}
}
Oct 18, 2019 11:27:46 PM FileEncryptorSkeleton main SEVERE: null javax.crypto.BadPaddingException: Given final block not properly padded. Such issues can arise if a bad key is used during decryption. at com.sun.crypto.provider.CipherCore.unpad(CipherCore.java:975) at com.sun.crypto.provider.CipherCore.fillOutputBuffer(CipherCore.java:1056) at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:853) at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:446) at javax.crypto.Cipher.doFinal(Cipher.java:2164) at FileEncryptorSkeleton.main(FileEncryptorSkeleton.java:174)
Cipher#update-和Cipher#doFinal-方法都使用inputBuffer.toString()，它只包含对象的名称class和哈希码，而不是实际数据缓冲区。
从 inputBuffer-byte[] 中读取前 bytesRead 个字节（之前从 in-BufferedInputStream 中读取）并处理它们 (Cipher#update) 是正确的：
outputBuffer = cipher.update(inputBuffer, 0, bytesRead);
包含 cipher#update 调用的循环仅在没有字节被读取到 inputBuffer-byte[] 时才会保留，因此最终处理适用 (Cipher#doFinal):
outputBuffer = cipher.doFinal();
此外，在 cipher#doFinal 调用之后的第二个 cipher#init 调用是不必要的 (Cipher#init)。