Android 平台更加安全的DES加密方式

其他 2018-11-11 05:10:52 阅读次数: 0

DES介绍

DES是Data Encryption Standard（数据加密标准）的缩写。它是由IBM公司研制的一种对称密码算法。DES是一个分组加密算法，典型的DES以64位（即8个字节）为分组对数据加密，加密和解密用的是同一个算法。它的密钥长度是56位（因为每个第8 位都用作奇偶校验），密钥可以是任意的56位的数，而且可以任意时候改变。

DES的安全性

DES算法的安全性主要取决于密钥的保密。通常我们会自定义一串64位的密钥，并且直接将该密钥保存在java层，这中方式如果被他人反编译后极容易拿到我们的密钥，因此通常更好的做法时将密钥保存在jni层，这样会使得别人的破解难度加大，使得我们的程序更加安全，在jni中使用DES算法的方式通常可以使用c/c++重写DES算法，也可以直接在jni中通过反射来使用Android中的DES算法，本文中采用的是通过反射来使用Android中的DES算法的方式。

常见的Android DES加解密代码示例

加密

/**
 * DES加密
 *
 * @param originalStr
 * @return
 */
public static String encryptByDes(String originalStr) {
    String result = null;
    byte[] tmpOriginalStr = null;
    try {
        if (!TextUtils.isEmpty(originalStr)) {
            tmpOriginalStr = originalStr.getBytes(CHARSET_NAME);
            // 创建一个密匙工厂
            SecretKeyFactory keyFactory = SecretKeyFactory
                    .getInstance(ALGORITHM_DES);
            // 创建一个DESKeySpec对象，KEY为自定义密钥常量
            DESKeySpec dks = new DESKeySpec(KEY.getBytes());
            // 将DESKeySpec对象转换成SecretKey对象
            SecretKey secretKey = keyFactory.generateSecret(dks);
            // 用密匙初始化Cipher对象
            Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
            // Cipher对象实际完成加密操作
            cipher.init(Cipher.ENCRYPT_MODE, secretKey);
            // 真正开始加密操作
            byte[] tmpEncypt = cipher.doFinal(tmpOriginalStr);
            if (tmpEncypt != null) {
                result = Base64.encodeToString(tmpEncypt, Base64.NO_WRAP);
            }
        }
    } catch (Exception e) {
        Log.e("Erro", e.getMessage());
    }
    return result;
}

解密

/***
 * DES 解密
 *
 * @param desStr
 * @return
 */
public static String decyptByDes(String desStr) {
    String result = null;
    try {
        if (!TextUtils.isEmpty(desStr)) {
            // 创建一个密匙工厂
            SecretKeyFactory keyFactory = SecretKeyFactory
                    .getInstance(ALGORITHM_DES);
            // 创建一个DESKeySpec对象,KEY为自定义密钥常量
            DESKeySpec dks = new DESKeySpec(KEY.getBytes());
            // 将DESKeySpec对象转换成SecretKey对象
            SecretKey secretKey = keyFactory.generateSecret(dks);
            // 用密匙初始化Cipher对象
            Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
            // Cipher对象实际完成解密操作
            cipher.init(Cipher.DECRYPT_MODE, secretKey);
            // 真正开始解密操作
            byte[] tmpDecypt = cipher.doFinal(Base64.decode(desStr,
                    Base64.NO_WRAP));
            if (tmpDecypt != null) {
                result = new String(tmpDecypt, CHARSET_NAME);
            }
        }
    } catch (Exception e) {
        Log.e("Erro", e.getMessage());
    }
    return result;
}

更加安全的Android DES加解密代码示例

加密

JNIEXPORT jstring JNICALL Java_EncryptionClient_encryptByDes
    (JNIEnv *env, jclass clzz, jstring jstr) {
  const char *des = "DES";
  const char *desP = "DES/ECB/PKCS5Padding";
  const char *charset = "UTF-8";
  if (jstr != NULL && env->GetStringLength(jstr) > 0) {
    jclass String = env->FindClass("java/lang/String");
    jmethodID String_getBytes = env->GetMethodID(String, "getBytes",
                                                 "(Ljava/lang/String;)[B");
    // 创建一个密匙工厂
    jclass SecretKeyFactory = env->FindClass("javax/crypto/SecretKeyFactory");
    jmethodID SecretKeyFactory_getInstance = env->GetStaticMethodID(SecretKeyFactory,
                                                                    "getInstance",
                                                                    "(Ljava/lang/String;)Ljavax/crypto/SecretKeyFactory;");
    jobject keyFactory = env->CallStaticObjectMethod(SecretKeyFactory,
                                                     SecretKeyFactory_getInstance,
                                                     env->NewStringUTF(des));
    // 创建一个DESKeySpec对象
    jclass DESKeySpec = env->FindClass("javax/crypto/spec/DESKeySpec");
    jmethodID DESKeySpec_init = env->GetMethodID(DESKeySpec, "<init>", "([B)V");
    // key为64位密钥
    jbyte *by = (jbyte *) key;
    jbyteArray keyByte = env->NewByteArray(64);
    env->SetByteArrayRegion(keyByte, 0, 64, by);
    jobject dks = env->NewObject(DESKeySpec, DESKeySpec_init, keyByte);
    // 将DESKeySpec对象转换成SecretKey对象
    jclass SecretKey = env->FindClass("javax/crypto/SecretKey");
    jmethodID SecretKeyFactory_generateSecret = env->GetMethodID(SecretKeyFactory,
                                                                 "generateSecret",
                                                                 "(Ljava/security/spec/KeySpec;)Ljavax/crypto/SecretKey;");
    jobject secretKey = env->CallObjectMethod(keyFactory, SecretKeyFactory_generateSecret,
                                              dks);
    // 用密匙初始化Cipher对象
    jclass Cipher = env->FindClass("javax/crypto/Cipher");
    jmethodID Cipher_getInstance = env->GetStaticMethodID(Cipher,
                                                          "getInstance",
                                                          "(Ljava/lang/String;)Ljavax/crypto/Cipher;");
    jobject cipher = env->CallStaticObjectMethod(Cipher, Cipher_getInstance,
                                                 env->NewStringUTF(desP));
    // Cipher对象实际完成加密操作
    jmethodID Cipher_init = env->GetMethodID(Cipher, "init", "(ILjava/security/Key;)V");
    env->CallVoidMethod(cipher, Cipher_init, 1, secretKey);
    // 真正开始加密操作
    jmethodID Cipher_doFinal = env->GetMethodID(Cipher, "doFinal", "([B)[B");
    jbyteArray plainStringBytes = (jbyteArray) env->CallObjectMethod(jstr,
                                                                     String_getBytes,
                                                                     env->NewStringUTF(
                                                                         charset));
    jbyteArray encryptStr = (jbyteArray) env->CallObjectMethod(cipher, Cipher_doFinal,
                                                               plainStringBytes);
    //释放对象
    env->DeleteLocalRef(String);
    env->DeleteLocalRef(SecretKeyFactory);
    env->DeleteLocalRef(keyFactory);
    env->DeleteLocalRef(DESKeySpec);
    env->DeleteLocalRef(dks);
    env->DeleteLocalRef(SecretKey);
    env->DeleteLocalRef(Cipher);
    env->DeleteLocalRef(keyByte);
    env->DeleteLocalRef(plainStringBytes);
    if (encryptStr != NULL) {
      //Base64编码
      jclass Base64 = env->FindClass("android/util/Base64");
      jmethodID Base64_encode = env->GetStaticMethodID(Base64, "encodeToString",
                                                       "([BI)Ljava/lang/String;");
      return (jstring) env->CallStaticObjectMethod(Base64, Base64_encode, encryptStr, 2);
    }
  }
  return NULL;
 
}

解密

JNIEXPORT jstring JNICALL Java_EncryptionClient_decryptByDes
    (JNIEnv *env, jclass clzz, jstring jstr) {
  const char *des = "DES";
  const char *desP = "DES/ECB/PKCS5Padding";
  const char *charset = "UTF-8";
  if (jstr != NULL && env->GetStringLength(jstr) > 0) {
    jclass String = env->FindClass("java/lang/String");
    jmethodID String_getBytes = env->GetMethodID(String, "getBytes", "(Ljava/lang/String;)[B");
    jmethodID String_init = env->GetMethodID(String, "<init>", "([BLjava/lang/String;)V");
    // 创建一个密匙工厂
    jclass SecretKeyFactory = env->FindClass("javax/crypto/SecretKeyFactory");
    jmethodID SecretKeyFactory_getInstance = env->GetStaticMethodID(SecretKeyFactory,
                                                                    "getInstance",
                                                                    "(Ljava/lang/String;)Ljavax/crypto/SecretKeyFactory;");
    jobject keyFactory = env->CallStaticObjectMethod(SecretKeyFactory,
                                                     SecretKeyFactory_getInstance,
                                                     env->NewStringUTF(des));
    // 创建一个DESKeySpec对象
    jclass DESKeySpec = env->FindClass("javax/crypto/spec/DESKeySpec");
    jmethodID DESKeySpec_init = env->GetMethodID(DESKeySpec, "<init>", "([B)V");
    // key为64位密钥
    jbyte *by = (jbyte *) key;
    jbyteArray keyByte = env->NewByteArray(64);
    env->SetByteArrayRegion(keyByte, 0, 64, by);
    jobject dks = env->NewObject(DESKeySpec, DESKeySpec_init, keyByte);
    // 将DESKeySpec对象转换成SecretKey对象
    jclass SecretKey = env->FindClass("javax/crypto/SecretKey");
    jmethodID SecretKeyFactory_generateSecret = env->GetMethodID(SecretKeyFactory,
                                                                 "generateSecret",
                                                                 "(Ljava/security/spec/KeySpec;)Ljavax/crypto/SecretKey;");
    jobject secretKey = env->CallObjectMethod(keyFactory, SecretKeyFactory_generateSecret, dks);
    // 用密匙初始化Cipher对象
    jclass Cipher = env->FindClass("javax/crypto/Cipher");
    jmethodID Cipher_getInstance = env->GetStaticMethodID(Cipher,
                                                          "getInstance",
                                                          "(Ljava/lang/String;)Ljavax/crypto/Cipher;");
    jobject cipher = env->CallStaticObjectMethod(Cipher, Cipher_getInstance,
                                                 env->NewStringUTF(desP));
    // Cipher对象实际完成解密操作
    jmethodID Cipher_init = env->GetMethodID(Cipher, "init", "(ILjava/security/Key;)V");
    env->CallVoidMethod(cipher, Cipher_init, 2, secretKey);
    //Base64解码
    jclass Base64 = env->FindClass("android/util/Base64");
    jmethodID Base64_decode = env->GetStaticMethodID(Base64, "decode",
                                                     "(Ljava/lang/String;I)[B");
    jbyteArray text = (jbyteArray) env->CallStaticObjectMethod(Base64, Base64_decode,
                                                               jstr, 2);
    // 真正开始解密操作
    jmethodID Cipher_doFinal = env->GetMethodID(Cipher, "doFinal", "([B)[B");
    jbyteArray decryptBytes = (jbyteArray) env->CallObjectMethod(cipher, Cipher_doFinal, text);
    //释放对象
    env->DeleteLocalRef(SecretKeyFactory);
    env->DeleteLocalRef(keyFactory);
    env->DeleteLocalRef(DESKeySpec);
    env->DeleteLocalRef(dks);
    env->DeleteLocalRef(SecretKey);
    env->DeleteLocalRef(Cipher);
    env->DeleteLocalRef(keyByte);
    env->DeleteLocalRef(Base64);
    env->DeleteLocalRef(text);
    if (decryptBytes != NULL) {
      return (jstring) env->NewObject(String, String_init, decryptBytes,
                                      env->NewStringUTF(charset));
    }
  }
  return NULL;
}

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