简单的AES加密和解密不返回原始文本

Question

我使用以下简单的加密和解密函数只是为了在使用更复杂的安全功能（如填充和散列）之前查看它是否有效。由于某种原因，返回的明文与原始消息不相似。代码如下：

public static byte[] encrypt(SecretKey secret, byte[] buffer) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidParameterSpecException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException
{
    /* Encrypt the message. */
    cipher = Cipher.getInstance("AES/CTR/NoPadding");
    cipher.init(Cipher.ENCRYPT_MODE, secret);
    byte[] ciphertext = cipher.doFinal(buffer);

    return ciphertext;
}

public static byte[] decrypt(SecretKey secret, byte[] buffer) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidParameterSpecException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException
{
    /* Decrypt the message. - use cipher instance created at encrypt */
    cipher.init(Cipher.DECRYPT_MODE, secret);
    byte[] clear = cipher.doFinal(buffer);

    return clear;
}

和调用代码：

    SecretKey secret1 = null;
    byte[] ciphertext = null;
    byte[] message = "Hello, World!".getBytes();
    byte[] clear = null;

    try {
// aSecret is a shared secret generated with ECDH
        secret1 = Crypto.createAESKey(aSecret);
        ciphertext = Crypto.encrypt(secret1, message);
        clear = Crypto.decrypt(secret1, ciphertext);

        String s = new  String(clear);//clear.toString();

        keyAText.setText(new String(message));
        keyBText.setText(s);

        return;
    } catch (InvalidKeySpecException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (NoSuchAlgorithmException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (InvalidKeyException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (NoSuchPaddingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (InvalidParameterSpecException 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();
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

Answer 1

这几乎可以肯定是因为您在初始化期间没有使用IvParameterSpec 提供 IV。在 Java SE 上，您的代码甚至不会运行，因为 CTR 需要 设置此参数。然而，其他提供者可能会以不同的方式实现事物，例如他们可能会提供随机静脉注射。

当然，如果你在加解密时使用不同的随机IV，你的解密结果很可能与你的明文不匹配。

尝试以下修正方法：

public static byte[] encrypt(SecretKey secret, byte[] buffer) throws GeneralSecurityException
{
    /* Encrypt the message. */
    Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");

    SecureRandom rng = new SecureRandom();
    byte[] ivData = new byte[cipher.getBlockSize()];
    rng.nextBytes(ivData);

    cipher.init(Cipher.ENCRYPT_MODE, secret, new IvParameterSpec(ivData));
    byte[] ciphertext = cipher.doFinal(buffer);

    return Arrays.concatenate(ivData, ciphertext);
}

public static byte[] decrypt(SecretKey secret, byte[] buffer) throws GeneralSecurityException
{
    /* Decrypt the message. - use cipher instance created at encrypt */
    Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");

    int n = cipher.getBlockSize();
    byte[] ivData = Arrays.copyOf(buffer, n);

    cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(ivData));
    byte[] clear = cipher.doFinal(buffer, n, buffer.length - n);

    return clear;
}