AndroidStudio下JNI开发（easy+1.0）之签名

最新推荐文章于 2021-05-26 04:26:05 发布

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最新推荐文章于 2021-05-26 04:26:05 发布 · 761 阅读

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概述

根据前面的文章来看，JNI其实只实现了关键代码加密，如果别人拿到了你的Java Native方法定义和对应的so，即可完成对你so里方法的调。因为native 方法和类都是不能混淆的，混淆了方法的函数名就变了，调用的时候就找不到方法了，因此如果反编译APK可以非常容易拿到相关文件和代码。显然我们需要一些手段来在JNI的验证请求接口的是不是我们的程序。

签名验证的原理

可以用如下图来表明加了验证之后调用JNI的逻辑，用一个isValid 来表明请求的应用是不是我们自己的应用。isValid 通过init 去初始化。
这里写图片描述

如何判别调用者的有效性

直接有效的方案就是使用签名进行判定，如果你的keystore没有泄漏，第三方破解概率几乎为零。当然这都是相对的，任何防护都会有破绽。大多数第三方的Android SDK也都通过签名来判断申请的key是否用在了你申请的应用上。因此在大多数SDK申请key的时候会让你填写SHA1，因为在程序运行的时候SDK会获取你签名的SHA1去向服务器验证，你申请的appkey和SHA1是否正确。

签名验证的实现

在代码中获取签名的SHA1

先尝试在Java代码中获取签名的SHA1

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> String <span class="hljs-title" style="box-sizing: border-box;">getCertSHA1</span>(Context context)
    {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span>
        {
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获取包管理器</span>
            PackageManager packageManager=context.getPackageManager();
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获取包名</span>
            String packageName=context.getPackageName();
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获得包信息</span>
            PackageInfo   pis = packageManager.getPackageInfo(packageName, PackageManager.GET_SIGNATURES);
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获得签名</span>
            Signature[] signs = pis.signatures; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//签名</span>
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获得签名数组的第一位</span>
            Signature sign=signs[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>];
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获得X.509证书工厂</span>
            CertificateFactory certFactory = CertificateFactory.getInstance(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"X.509"</span>);

            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">byte</span>[] signBytes=sign.toByteArray();
            ByteArrayInputStream byteIn=<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ByteArrayInputStream(signBytes);
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获取X509证书</span>
            X509Certificate cert = (X509Certificate) certFactory.generateCertificate(byteIn);
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获取证书发行者SHA1</span>
            MessageDigest sha1=MessageDigest.getInstance(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"SHA1"</span>);
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">byte</span>[] certByte=cert.getEncoded();
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">byte</span>[] bs=sha1.digest (certByte);
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> toHex(bs);
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (CertificateException e)
        {

            e.printStackTrace();
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (Exception e)
        {
            e.printStackTrace();
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;
    }

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//将Byte转换成HexString 辅助函数</span>
     <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>[] cs=<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">16</span>];
    {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;i < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>;i++)
        {
            cs[i] = (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>) (<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'0'</span> + i);
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>;i < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">16</span>;i++)
        {
            cs[i] = (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>) (<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'A'</span> + i - <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>);
        }
    }
    String toHex(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">byte</span>[] bs)
    {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>[] cs=<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>[bs.length * <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>];
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> x;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;i < bs.length;i++)
        {
            x = bs[i] & <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0xff</span>;
            cs[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> * i] = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.cs[x / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">16</span>];
            cs[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> * i + <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>] = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.cs[x % <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">16</span>];
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> String(cs);
    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: