函数解密抛出 javax.crypto.BadPaddingException：android 中的 SimpleCrypto 类中的填充块已损坏

我正在编写一个 Android 应用程序来解密存储在文件中的一些文本。我使用了以下代码 -

public class SimpleCrypto {
    public static String encrypt(String seed, String cleartext)
            throws Exception {
        byte[] rawKey = getRawKey(seed.getBytes());
        byte[] result = encrypt(rawKey, cleartext.getBytes());
        return toHex(result);
    }

    public static String decrypt(String seed, String encrypted)
            throws Exception {
        byte[] rawKey = getRawKey(seed.getBytes());
        byte[] enc = toByte(encrypted);
        byte[] result = decrypt(rawKey, enc);
        return new String(result);
    }

    private static byte[] getRawKey(byte[] seed) throws Exception {
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");
        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) throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        byte[] encrypted = cipher.doFinal(clear);
        return encrypted;
    }

    private static byte[] decrypt(byte[] raw, byte[] encrypted)
            throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        byte[] decrypted = cipher.doFinal(encrypted);//this is the line that throws error
        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));
    }

}

编辑：这是我试图解密的文本 -

39D4CA73AAF2D42C32659FDC5D1848EA

用这把钥匙 -

thebestsecret153

如果有帮助的话。它应该显示in153.

编辑：在 android 中引发错误的行。 -

byte[] decrypted = cipher.doFinal(encrypted);

我还在 swing 中创建了一个项目来读取文件并收到以下错误 -

javax.crypto.BadPaddingException: Given final block not properly padded
    at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:811)
    at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:811)
    at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:676)
    at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:313)
    at javax.crypto.Cipher.doFinal(Cipher.java:2087)
    at decrypt.Decrypt.decrypt(Decrypt.java:43)
    at decrypt.MainForm.jButton1MouseClicked(MainForm.java:91)
    at decrypt.MainForm.access$000(MainForm.java:20)
    at decrypt.MainForm$1.mouseClicked(MainForm.java:46)
    at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:270)
    at java.awt.Component.processMouseEvent(Component.java:6508)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3320)
    at java.awt.Component.processEvent(Component.java:6270)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4501)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2719)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:694)
    at java.awt.EventQueue$3.run(EventQueue.java:692)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:708)
    at java.awt.EventQueue$4.run(EventQueue.java:706)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at java.lang.String.<init>(String.java:556)
    at decrypt.MainForm.jButton1MouseClicked(MainForm.java:91)
    at decrypt.MainForm.access$000(MainForm.java:20)
    at decrypt.MainForm$1.mouseClicked(MainForm.java:46)
    at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:270)
    at java.awt.Component.processMouseEvent(Component.java:6508)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3320)
    at java.awt.Component.processEvent(Component.java:6270)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4501)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2719)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:694)
    at java.awt.EventQueue$3.run(EventQueue.java:692)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:708)
    at java.awt.EventQueue$4.run(EventQueue.java:706)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

如果加密和解密在同一个程序中完成，则效果完美。

任何帮助表示赞赏。提前致谢。

TL;DR: SecureRandom.getInstance("SHA1PRNG")可能并不总是返回相同的结果even当用相同的种子播种时。

您已经走进了某些人设置的陷阱，他们认为伪随机数生成器 (PRNG) 与密钥导出函数 (KDF) 是一样的。总的来说，它们的运作非常接近。唯一的问题是，对于 Android 的加密提供程序实现（的某些实现），setSeed method adds种子是随机的，即使是第一次调用。所以你每次都会生成不同的密钥。不同的密钥意味着可能永远无法解密的随机密文。

随机密文意味着填充很可能是不正确的，因为使用错误密钥的 ECB 或 CBC 解密仍然返回明文 - 它只是随机的，就像密文一样。取消填充例程是likely在随机明文上失败，因此解密将失败并出现填充异常。请注意，经过身份验证的密码（例如 GCM 模式加密）将在另一方面always如果使用错误的密钥，则会失败。

解决方案：使用真正的随机 AES 密钥，或使用内置 PBKDF2 功能从密码（和盐）派生密钥。您可以查看如何执行此操作的示例here https://stackoverflow.com/q/992019/589259.

使用 SecureRandom 进行密钥导出函数的问题：

• the SecureRandom每个提供商/运行时的算法可能（并且确实）有所不同；
• the SecureRandom每个提供程序/运行时的实现可能有所不同；
• the SecureRandom实现可以在第一次调用期间添加或替换种子SecureRandom;

最后，一些提供商在以下情况下返回完全不同的随机数生成器："SHA1PRNG"被使用，因为许多人似乎默认这样做。创建随机数生成器时只需使用new SecureRandom相反并记住"SHA1PRNG"不表示特定的算法。

对于提供者，我指的是加密服务提供者，如 Java 加密体系结构 (JCA) 中所述；即一个java.security.Provider.