Question

处理解密方法时遇到问题。加密产生了正确的输出但是当我解密完全相同的加密字符串时（应该回到明文字符串中），它不起作用。

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class Samp {

    private static String IV = "aaaaaaaaaaaaaaaa";
    private static final String UNICODE_FORMAT = "UTF8";

    private String padd(String plaintext) {
        while (plaintext.length() % 16 != 0) {
            plaintext += "\0";
        }
        return plaintext;
    }

    public String encryptString(String plaintext, String encryptionKey) {
        try {
            byte[] cipher = encrypt(padd(plaintext), encryptionKey);
            return new String(cipher, UNICODE_FORMAT);
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return null;
    }

    public String decryptString(String encString, String encryptionKey) {
        try {
            System.out.println("**** decryptString ****");
            System.out.println("enc = " + encString);
            System.out.println("key = " + encryptionKey);

            String decrypted = decrypt(encString.getBytes(UNICODE_FORMAT), encryptionKey);
            return decrypted;
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return null;
    }

    private static byte[] encrypt(String plainText, String encryptionKey) throws Exception {
        Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding", "SunJCE");
        SecretKeySpec key = new SecretKeySpec(encryptionKey.getBytes(UNICODE_FORMAT), "AES");
        cipher.init(Cipher.ENCRYPT_MODE, key, new IvParameterSpec(IV.getBytes(UNICODE_FORMAT)));
        return cipher.doFinal(plainText.getBytes(UNICODE_FORMAT));
    }

    private static String decrypt(byte[] cipherText, String encryptionKey) throws Exception {
        Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding", "SunJCE");
        SecretKeySpec key = new SecretKeySpec(encryptionKey.getBytes(UNICODE_FORMAT), "AES");
        cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(IV.getBytes(UNICODE_FORMAT)));
        return new String(cipher.doFinal(cipherText), UNICODE_FORMAT);
    }
    // implement methods here
    // using AES simple encryption

    public static void main(String[] args){
        String plaintext = "Hello World!";
        String key = "asdfqaqwsaerdqsw";

        Samp s = new Samp();
        String enc = s.encryptString(plaintext, key);
        System.out.println("encrypted string = " + enc);
        String dec = s.decryptString(enc, key);
        System.out.println("decrypted string = " + dec);
    }
}

我已经看过post，这与我的问题相同。我按照建议（更改getBytes（） - ＆gt; getBytes（UNICODE_FORMAT））但它仍然是相同的。我仍然得到一个异常（javax.crypto.IllegalBlockSizeException：输入长度不是16字节的倍数）

Answer 1

  public String encryptString(String plaintext, String encryptionKey)

问题就在这里。 String不是二进制数据的容器。此方法应返回byte []。类似地，decrypt（）方法应该使用byte []作为密文参数，而不是String。

Answer 2

您应该使用在字符和字节之间进行1对1映射的编码，例如“ISO-8859-1”。所以将代码更改为

private static final String UNICODE_FORMAT = "ISO-8859-1";

解决了这个问题。

Answer 3

这是我的代码

public static String encrypt(String data) throws Exception {

        SecretKeySpec key = generateKey();
        final Cipher c = Cipher.getInstance("AES/EAX/NoPadding", "BC");

        c.init(Cipher.ENCRYPT_MODE, key, ivSpec);

        byte[] encVal = c.doFinal(data.getBytes("UTF8"));       

        String encryptedValue = Hex.toHexString(encVal);
        return encryptedValue;
    }

    public static String decrypt(String encryptedData) throws Exception {

        Key key = generateKey();
        final Cipher c = Cipher.getInstance("AES/EAX/NoPadding", "BC");

        c.init(Cipher.DECRYPT_MODE, key, ivSpec);
        byte[] ba = Hex.decode(encryptedData);

        byte[] encVal = c.doFinal(ba);  

        return new String (encVal);

    }

解密字符串会生成IllegalBlockSizeException

3 个答案: