是J2ME的新手。目前我被告知做一个需要AES加密的项目。我在谷歌搜索后得到了一段代码片段。代码确实加密但是在尝试解密时遇到错误“Invalidkeyexception”
代码是
package com.cellapp.voda.vault.others;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import javax.crypto.*;
import javax.crypto.spec.SecretKeySpec;
public class Codec {
private Cipher cipher = null;
private boolean operative = true;
public Codec() {
try {
cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
} catch (NoSuchAlgorithmException e) {
// This should not happen since we know the target platform
// but we set the operative flag to false just in case
operative = false;
} catch (NoSuchPaddingException e) {
// This should not happen since we know the target platform
// but we set the operative flag to false just in case
operative = false;
}
}
public void encrypt(byte[] keyBits, byte[] plaintext)
throws InvalidKeySpecException, InvalidKeyException,
IllegalStateException, ShortBufferException,
IllegalBlockSizeException, BadPaddingException,
InvalidAlgorithmParameterException {
byte[] cipherText = null;
if (operative) {
try{
// Initialize the key from the password
Key key = new SecretKeySpec(keyBits, 0, keyBits.length, "AES");
// add 2 bytes to encode the length of the plaintext
// as a short value
byte[] plaintextAndLength = new byte[plaintext.length + 2];
plaintextAndLength[0] = (byte) (0xff & (plaintext.length >> 8));
plaintextAndLength[1] = (byte) (0xff & plaintext.length);
// build the new plaintext
System.arraycopy(plaintext,
0,
plaintextAndLength,
2,
plaintext.length);
// calculate the size of the ciperthext considering
// the padding
int blocksize = 16;
int ciphertextLength = 0;
int remainder = plaintextAndLength.length % blocksize;
if (remainder == 0) {
ciphertextLength = plaintextAndLength.length;
} else {
ciphertextLength = plaintextAndLength.length - remainder
+ blocksize;
}
cipherText = new byte[ciphertextLength];
// reinitialize the cipher in encryption mode with the given key
cipher.init(Cipher.ENCRYPT_MODE, key);
// do the encryption
cipher.doFinal(plaintextAndLength,
0,
plaintextAndLength.length,
cipherText,
0);
}
catch(Exception e)
{
System.out.println("TT " + cipherText);
}
} else {
throw new IllegalStateException("Codec not initialized");
}
}
public void decrypt(byte[] keyBits, byte[] cipherText)
throws InvalidKeySpecException, InvalidKeyException,
IllegalStateException, ShortBufferException,
IllegalBlockSizeException, BadPaddingException,
InvalidAlgorithmParameterException {
if (operative) {
// create a key from the keyBits
Key key = new SecretKeySpec(keyBits, 0, keyBits.length, "AES");
// Initialize the cipher in decrypt mode
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] decrypted = new byte[cipherText.length];
// Decrypt the cipher text
cipher.doFinal(cipherText, 0, cipherText.length, decrypted, 0);
// Calculate the length of the plaintext
int plainTextLength = (decrypted[0] << 8)
| (decrypted[1] & 0xff);
byte[] finalText = new byte[plainTextLength];
// Decode the final text
System.arraycopy(decrypted, 2, finalText, 0, plainTextLength);
System.out.println("fina; text " + finalText);
} else {
throw new IllegalStateException("Codec not initialized");
}
}
// Displays ecrypted data in hex
public String byteToHex(byte[] data) {
StringBuffer hexString = new StringBuffer();
String hexCodes = "0123456789ABCDEF";
for (int i = 0; i < data.length; i++) {
hexString.append(hexCodes.charAt((data[i] >> 4) & 0x0f));
hexString.append(hexCodes.charAt(data[i] & 0x0f));
if (i < data.length - 1) {
hexString.append(":");
}
if (((i + 1) % 8) == 0) {
hexString.append("\n");
}
}
return hexString.toString();
}
}
答案 0 :(得分：1)
你列出的代码很糟糕有很多原因（使用ECB，Cipher不是线程安全的，没有正确填充等等），我强烈建议你不要使用它。
我躺着，你应该用它代替。
public static void main(String[] args) throws DecoderException, InvalidKeyException,
NoSuchAlgorithmException, NoSuchPaddingException, InvalidAlgorithmParameterException,
IllegalBlockSizeException, BadPaddingException {
//Hex encoding/decoding done with Apache Codec library.
//key MUST BE 16, 24 or 32 random bytes.
//Do not reuse this key! Create your own.
byte[] key = Hex.decodeHex("a3134dfd51c30f6e25343d861320668e".toCharArray());
String text = "This is some test text.";
byte[] encrypted = encrypt(key, text.getBytes());
byte[] decrypted = decrypt(key, encrypted);
System.out.println("Text: " + text);
System.out.println("Encrypted: " + Hex.encodeHexString(encrypted));
System.out.println("Decrypted: " + new String(decrypted));
}
public static byte[] encrypt(byte[] key, byte[] unencrypted) throws NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException,
IllegalBlockSizeException, BadPaddingException{
//Create an initialization vector
//SecureRandom is not available on J2ME, so we use Bouncy Castle's DigestRandomGenerator instead.
DigestRandomGenerator rnd = new DigestRandomGenerator(new SHA1Digest());
//SecureRandom rnd = new SecureRandom();
byte[] iv = new byte[16];
rnd.nextBytes(iv);
IvParameterSpec ivSpec = new IvParameterSpec(iv);
//Set up the cipher and encrypt
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key, "AES"), ivSpec);
byte[] encrypted = cipher.doFinal(unencrypted);
//Append the encrypted text to the IV
byte[] output = new byte[iv.length + encrypted.length];
System.arraycopy(iv, 0, output, 0, iv.length);
System.arraycopy(encrypted, 0, output, iv.length, encrypted.length);
return output;
}
public static byte[] decrypt(byte[] key, byte[] encrypted) throws NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException,
IllegalBlockSizeException, BadPaddingException{
//Separate the IV and encrypted text
byte[] iv = new byte[16];
byte[] encryptedText = new byte[encrypted.length - iv.length];
System.arraycopy(encrypted, 0, iv, 0, iv.length);
System.arraycopy(encrypted, iv.length, encryptedText, 0, encryptedText.length);
//Decrypt the encrypted text
IvParameterSpec ivSpec = new IvParameterSpec(iv);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "AES"), ivSpec);
byte[] decrypted = cipher.doFinal(encryptedText);
return decrypted;
}