Android：加密字符串、通过 HTTPS 发送和解密字符串问题

Question

我必须加密一个字符串才能通过 HTTPS 发送到服务器。然后，在服务器端，我必须解密字符串并使用它。

我在两侧都使用了这段代码：

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");

    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);

    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));
}

}

在android上，使用“123456789”作为种子，rawKey给我：

[99, 51, -103, -58, 81, -52, 90, -103, -114, 70, - 128, -25, -105, -124, -128, -67]

但在服务器端，使用相同的种子，给我：

[-52, 103, 4, 60, 123, -49, -11, -18, -91, 86, 107, -39, -79, -13, -57, 79]

我不明白为什么。 Android 上的 javax.crypto.KeyGenerator 有什么不同吗？我做错了什么？

拜托，我需要一些帮助。

非常感谢你

对不起我的英语不好

----------------------------更新----------- ------------------------------------------

这是我的新代码：

public class DesEncrypter {

    public static final int SALT_LENGTH = 20;
    public static final int PBE_ITERATION_COUNT = 1024;

    private static final String RANDOM_ALGORITHM = "SHA1PRNG";
    private static final String PBE_ALGORITHM = "PBEWithSHA256And256BitAES-CBC-BC";
    private static final String CIPHER_ALGORITHM = "AES/CBC/PKCS5Padding";


    public byte[] encrypt(String password, String cleartext) {

        byte[] encryptedText = null;

        try {
            byte[] salt = "dfghjklpoiuytgftgyhj".getBytes();

            PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray(), salt, PBE_ITERATION_COUNT, 256);

            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBEWITHSHAAND256BITAES-CBC-BC");

            SecretKey tmp = factory.generateSecret(pbeKeySpec);

            SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

            byte[] key = secret.getEncoded();

            Cipher encryptionCipher = Cipher.getInstance(CIPHER_ALGORITHM);   

            byte[] iv = generateIv();

            IvParameterSpec ivspec = new IvParameterSpec(iv);

            encryptionCipher.init(Cipher.ENCRYPT_MODE, secret, ivspec);

            encryptedText = encryptionCipher.doFinal(cleartext.getBytes());

        } catch (Exception e) {
            e.printStackTrace();
        }

        return encryptedText;
    }

    public String decrypt(String password, byte[] encryptedText) {

        String cleartext = "";

        try {
            byte[] salt = "dfghjklpoiuytgftgyhj".getBytes();

            PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray(), salt, PBE_ITERATION_COUNT, 256);

            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBEWITHSHAAND256BITAES-CBC-BC");

            SecretKey tmp = factory.generateSecret(pbeKeySpec);

            SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

            byte[] key = secret.getEncoded();

            Cipher decryptionCipher = Cipher.getInstance(CIPHER_ALGORITHM);

            byte[] iv = generateIv();

            IvParameterSpec ivspec = new IvParameterSpec(iv);

            decryptionCipher.init(Cipher.DECRYPT_MODE, secret, ivspec);

            byte[] decryptedText = decryptionCipher.doFinal(encryptedText);

            cleartext =  new String(decryptedText); 

        } catch (Exception e) {
            e.printStackTrace();
        }

        return cleartext;
    }   

    private byte[] generateIv() throws NoSuchAlgorithmException {

        SecureRandom random = SecureRandom.getInstance(RANDOM_ALGORITHM);

        byte[] iv = new byte[16];

        random.nextBytes(iv);

        return iv;
    }

}

----------------------------在 Android 上运行的最终代码！------------------------ -----------------

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;

public class DesEncrypter {

    public static final int SALT_LENGTH = 20;
    public static final int PBE_ITERATION_COUNT = 200; //1024;

    private static final String PBE_ALGORITHM = "PBEWithSHA256And256BitAES-CBC-BC";

    //algoritmo / modo / relleno 
    private static final String CIPHER_ALGORITHM = "AES/CBC/PKCS5Padding";

    byte[] iv = "1234567890asdfgh".getBytes();

    byte[] salt = "dfghjklpoiuytgftgyhj".getBytes();

    public byte[] encrypt(String password, String cleartext) {

        byte[] encryptedText = null;

        try {


            PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray(), salt, PBE_ITERATION_COUNT, 256);

            //Factoria para crear la SecretKey, debemos indicar el Algoritmo
            SecretKeyFactory factory = SecretKeyFactory.getInstance(PBE_ALGORITHM);

            SecretKey tmp = factory.generateSecret(pbeKeySpec);

            //Creamos una llave;
            SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

            //Obtenemos la llave, solo informativo
            byte[] key = secret.getEncoded();

            //La clase Cipher, se usa para cifrar mediante algoritmos de  clave simétrica
            Cipher encryptionCipher = Cipher.getInstance(CIPHER_ALGORITHM);   

            //byte[] iv = generateIv();

            IvParameterSpec ivspec = new IvParameterSpec(iv);

            //Accion, SecretKey, parameter specification for an initialization vector
            encryptionCipher.init(Cipher.ENCRYPT_MODE, secret, ivspec);

            //Realizamos el cifrado
            encryptedText = encryptionCipher.doFinal(cleartext.getBytes());

        } catch (Exception e) {
            e.printStackTrace();
        }

        return encryptedText;
    }

    public String decrypt(String password, byte[] encryptedText) {

        String cleartext = "";

        try {

            PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray(), salt, PBE_ITERATION_COUNT, 256);

            //Factoria para crear la SecretKey, debemos indicar el Algoritmo
            SecretKeyFactory factory = SecretKeyFactory.getInstance(PBE_ALGORITHM);

            SecretKey tmp = factory.generateSecret(pbeKeySpec);

            //Creamos una llave;
            SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

            //Obtenemos la llave, solo informativo
            byte[] key = secret.getEncoded();

            //La clase Cipher, se usa para cifrar mediante algoritmos de  clave simétrica
            Cipher decryptionCipher = Cipher.getInstance(CIPHER_ALGORITHM);

            //byte[] iv = generateIv();

            IvParameterSpec ivspec = new IvParameterSpec(iv);

            //Accion, SecretKey, parameter specification for an initialization vector
            decryptionCipher.init(Cipher.DECRYPT_MODE, secret, ivspec);

            //Realizamos el descifrado
            byte[] decryptedText = decryptionCipher.doFinal(encryptedText);

            cleartext =  new String(decryptedText); 

        } catch (Exception e) {
            e.printStackTrace();
        }

        return cleartext;
    }      
}

Answer 1

如果您首先使用 SSL 为什么要加密？ HTTPS (SSL) 将对传输中的数据进行加密，并在服务器上自动解密。此外，您的自定义加密方案很可能不如 SSL 安全。

您的错误在于如何派生密钥：setSeed() 不会替换随机数生成器的状态，它只会增强它。这意味着即使您将相同的字节传递给 setSeed()，generateKey() 也很可能会生成不同的密钥。使用 PBE （基于密码的加密）类派生密码中的密钥。或者确保您的服务器和客户端以其他方式使用相同的密钥。

下面是从密码生成密钥的示例（适用于 Android）。您需要找到 Android 和您的服务器都支持的 PBE 算法。如果您在服务器应用程序中使用 JCE Bouncy Castle 提供程序，它应该支持与 Android 相同的算法（Android 使用 Bouncy Castle 作为其 JCE 实现的一部分）。

SecretKeyFactory factory = 
    SecretKeyFactory.getInstance("PBEWITHSHAAND256BITAES-CBC-BC");
KeySpec spec = new PBEKeySpec("password".toCharArray(), salt, 1024, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");