我需要加密一个字符串然后解密。加密函数运行良好，但是当我将加密值传递给解密函数时，我收到空指针异常。如果我在 Java 应用程序中使用相同的代码，一切都运行良好。
public class Cripthografy {
private static String TAG="freeliberomail";
public static String encrypt(String seed, String cleartext){
byte[] rawKey;
byte[] result=null;
try {
rawKey = getRawKey(seed.getBytes());
result = encrypt(rawKey, cleartext.getBytes());
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return toHex(result);
}
public static String decrypt(String seed, String encrypted) {
byte[] rawKey;
byte[] result=null;
try {
rawKey = getRawKey(seed.getBytes());
byte[] enc = toByte(encrypted);
result = decrypt(rawKey, enc);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return new String(result);
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(seed);
kgen.init(128, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
return raw;
}
private static byte[] encrypt(byte[] raw, byte[] clear){
byte[] encrypted=null;
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher;
try {
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
encrypted = cipher.doFinal(clear);
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvalidKeyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (BadPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return encrypted;
}
private static byte[] decrypt(byte[] raw, byte[] encrypted) {
byte[] decrypted = null;
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher;
try {
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
decrypted = cipher.doFinal(encrypted);
}catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvalidKeyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (BadPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return decrypted;
}
public static String toHex(String txt) {
return toHex(txt.getBytes());
}
public static String fromHex(String hex) {
return new String(toByte(hex));
}
public static byte[] toByte(String hexString) {
int len = hexString.length()/2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
return result;
}
public static String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer(2*buf.length);
for (int i = 0; i < buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private final static String HEX = "0123456789ABCDEF";
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
}
}
然后我打电话:
String encValue=Cripthografy.encrypt("MY_KEY", "helloworld");
String decValue=Cripthografy.decrypt("MY_KEY", encValue);
Log.d(TAG,"encript:"+encValue+" "+"decript:"+decValue);
异常(exception)是:
01-17 03:57:23.986: W/System.err(29846): javax.crypto.BadPaddingException: pad block corrupted
01-17 03:57:23.991: W/System.err(29846): at com.android.org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(B aseBlockCipher.java:709)
01-17 03:57:23.991: W/System.err(29846): at javax.crypto.Cipher.doFinal(Cipher.java:1111)
01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Cripthografy.decrypt(Cripthografy.java:111)
01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Cripthografy.decrypt(Cripthografy.java:55)
01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Auth.writeCookieTofile(Auth.java:307)
01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Auth.createSessionCookie(Auth.java:287)
01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Auth.scenario(Auth.java:196)
01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Auth.accessMail(Auth.java:117)
01-17 03:57:23.991: W/System.err(29846): at marvellous.freeliberomail.Auth.run(Auth.java:96)
01-17 03:57:23.991: W/System.err(29846): at java.lang.Thread.run(Thread.java:856)
01-17 03:57:23.996: W/dalvikvm(29846): threadid=11: thread exiting with uncaught exception (group=0x41584930)
01-17 03:57:23.996: E/AndroidRuntime(29846): FATAL EXCEPTION: Thread-32785
01-17 03:57:23.996: E/AndroidRuntime(29846): java.lang.NullPointerException
01-17 03:57:23.996: E/AndroidRuntime(29846): at java.lang.String.<init>(String.java:141)
01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Cripthografy.decrypt(Cripthografy.java:60)
01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Auth.writeCookieTofile(Auth.java:307)
01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Auth.createSessionCookie(Auth.java:287)
01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Auth.scenario(Auth.java:196)
01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Auth.accessMail(Auth.java:117)
01-17 03:57:23.996: E/AndroidRuntime(29846): at marvellous.freeliberomail.Auth.run(Auth.java:96)
01-17 03:57:23.996: E/AndroidRuntime(29846): at java.lang.Thread.run(Thread.java:856)
最佳答案
是的，android Cipher 确实有一些问题。 一是 cipher.doFinal(encrypted) 中的 byte[] 有时必须具有正确的长度。尝试用 128 位的加密数组输入它(用 0 填充？)
经过许多痛苦的时间，这个例子终于起作用了:
private static byte[] key = "12345678".getBytes();// 64 bit
private static byte[] iv = "12345678".getBytes();
public static String encrypt(String in) {
String cypert = in;
try {
IvParameterSpec ivSpec = new IvParameterSpec(iv);
SecretKeySpec k = new SecretKeySpec(key, "DES");
Cipher c = Cipher.getInstance("DES/CBC/PKCS7Padding");
c.init(Cipher.ENCRYPT_MODE, k, ivSpec);
byte[] encryptedData = c.doFinal(in.getBytes());
cypert = Base64.encodeLines(encryptedData);
} catch (Exception e) {
Debugger.error(e);
}
return cypert;
}
public static String decrypt(String in) throws Exception {
String plain=in;
try {
IvParameterSpec ivSpec = new IvParameterSpec(iv);
SecretKeySpec keys = new SecretKeySpec(key, "DES");
Cipher cipher = Cipher.getInstance("DES/CBC/PKCS7Padding");
cipher.init(Cipher.DECRYPT_MODE, keys, ivSpec);
// decryption pass
byte[] cipherText = Base64.decodeLines(in);
int ctLength = cipherText.length;
byte[] plainText = new byte[cipher.getOutputSize(ctLength)];
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bos.write(cipher.doFinal(cipherText));
plainText = bos.toByteArray();
bos.close();
plain = new String(plainText, "UTF8");
} catch (Exception e) {
Debugger.error(e);
}
return plain;
}
关于Android - Crittografy Cipher 解密不起作用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14371709/