无涯教程-Java加密 - 获取密钥在本章中，无涯教程将学习如何使用Java密码术从密钥库中检索密钥。要从密钥库中检

在本章中，无涯教程将学习如何使用Java密码术从密钥库中检索密钥。

要从密钥库中检索密钥，请遵循以下步骤。

步骤1 - 创建KeyStore对象

java.security 包的 KeyStore 类的 getInstance()方法接受一个表示密钥库类型的字符串值，并返回一个KeyStore宾语。

如下所示，使用此方法创建KeyStore类的对象。

//创建 KeyStore 对象
KeyStore keyStore=KeyStore.getInstance("JCEKS");

步骤2 - 加载KeyStore对象

KeyStore类的 load()方法接受表示密钥库文件的 FileInputStream对象和指定密钥库密码的String参数。

通常，密钥库存储在名为 cacerts 的文件中，位于位置 C:/Program Files/Java/jre1.8.0_101/lib/security/及其默认位置。密码为 changeit ，请使用 load()方法加载，如下所示。

//加载 KeyStore 对象
char[] password="changeit".toCharArray();
String path="C:/Program Files/Java/jre1.8.0_101/lib/security/cacerts";
java.io.FileInputStream fis=new FileInputStream(path);
keyStore.load(fis, password);

步骤3 - 创建ProtectionParameter对象

如下所示实例化KeyStore.ProtectionParameter。

//创建 KeyStore.ProtectionParameter 对象
KeyStore.ProtectionParameter protectionParam=new KeyStore.PasswordProtection(password);

步骤4 - 创建SecretKey对象

通过实例化其子类 SecretKeySpec 创建 SecretKey (接口) 对象。实例化时，您需要将密码和算法作为参数传递给其构造函数，如下所示。

//创建 SecretKey 对象
SecretKey mySecretKey=new SecretKeySpec(new String(keyPassword).getBytes(), "DSA");

步骤5 - 创建SecretKeyEntry对象

通过传递在上述步骤中创建的 SecretKey对象，创建 SecretKeyEntry 类的对象，如下所示。

//创建 SecretKeyEntry 对象
KeyStore.SecretKeyEntry secretKeyEntry=new KeyStore.SecretKeyEntry(mySecretKey);

步骤6 - 设置实体

KeyStore 类的 setEntry()方法接受一个表示密钥库实体别名的String参数，一个 SecretKeyEntry对象，一个ProtectionParameter对象，并存储给定别名下的实体。

如下所示，使用 setEntry()方法将实体设置为密钥库。

//将条目设置为密钥库
keyStore.setEntry("secretKeyAlias", secretKeyEntry, protectionParam);

步骤7 - 创建SecretKeyEntry对象

KeyStore类的 getEntry()方法接受一个别名(字符串参数)，以及ProtectionParameter类的一个对象作为参数并返回一个 KeyStoreEntry对象，然后可以将其强制转换将其放入 KeyStore.SecretKeyEntry对象。

如下所示，将所需密钥的别名和前面步骤中创建的保护参数对象传递给 getEntry()方法，从而创建KeyStore.SecretKeyEntry类的对象。

//创建 KeyStore.SecretKeyEntry 对象
KeyStore.SecretKeyEntry secretKeyEnt=(KeyStore.SecretKeyEntry)keyStore.getEntry("secretKeyAlias", protectionParam);

步骤8 - 创建实体的键对象

SecretKeyEntry 类的 getSecretKey()方法返回一个SecretKey对象。使用此方法创建一个SecretKey对象，如下所示。

//创建 SecretKey 对象
SecretKey mysecretKey=secretKeyEnt.getSecretKey();      
System.out.println(mysecretKey);

完整示例

以下示例显示了如何从密钥库中检索密钥。在这里，无涯教程将密钥存储在密钥库中，该密钥库位于"证书"文件(Windows 10操作系统)中，进行检索，并显示其某些属性，例如用于生成密钥的算法以及检索到的密钥。

import java.io.FileInputStream;
import java.security.KeyStore;
import java.security.KeyStore.ProtectionParameter;
import java.security.KeyStore.SecretKeyEntry;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
public class RetrievingFromKeyStore{
public static void main(String args[]) throws Exception{
//创建 KeyStore 对象
KeyStore keyStore = KeyStore.getInstance("JCEKS");
  </span><span class="com">//加载 KeyStore 对象</span><span class="pln">
  </span><span class="kwd">char</span><span class="pun">[]</span><span class="pln"> password </span><span class="pun">=</span><span class="pln"> </span><span class="str">"changeit"</span><span class="pun">.</span><span class="pln">toCharArray</span><span class="pun">();</span><span class="pln">
  java</span><span class="pun">.</span><span class="pln">io</span><span class="pun">.</span><span class="typ">FileInputStream</span><span class="pln"> fis </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">FileInputStream</span><span class="pun">(</span><span class="pln">
     </span><span class="str">"C:/Program Files/Java/jre1.8.0_101/lib/security/cacerts"</span><span class="pun">);</span><span class="pln">
  
  keyStore</span><span class="pun">.</span><span class="pln">load</span><span class="pun">(</span><span class="pln">fis</span><span class="pun">,</span><span class="pln"> password</span><span class="pun">);</span><span class="pln">
  
  </span><span class="com">//创建 KeyStore.ProtectionParameter 对象</span><span class="pln">
  </span><span class="typ">ProtectionParameter</span><span class="pln"> protectionParam </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">KeyStore</span><span class="pun">.</span><span class="typ">PasswordProtection</span><span class="pun">(</span><span class="pln">password</span><span class="pun">);</span><span class="pln">

  </span><span class="com">//创建 SecretKey 对象</span><span class="pln">
  </span><span class="typ">SecretKey</span><span class="pln"> mySecretKey </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">SecretKeySpec</span><span class="pun">(</span><span class="str">"myPassword"</span><span class="pun">.</span><span class="pln">getBytes</span><span class="pun">(),</span><span class="pln"> </span><span class="str">"DSA"</span><span class="pun">);</span><span class="pln">
  
  </span><span class="com">//创建 SecretKeyEntry 对象</span><span class="pln">
  </span><span class="typ">SecretKeyEntry</span><span class="pln"> secretKeyEntry </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">SecretKeyEntry</span><span class="pun">(</span><span class="pln">mySecretKey</span><span class="pun">);</span><span class="pln">
  keyStore</span><span class="pun">.</span><span class="pln">setEntry</span><span class="pun">(</span><span class="str">"secretKeyAlias"</span><span class="pun">,</span><span class="pln"> secretKeyEntry</span><span class="pun">,</span><span class="pln"> protectionParam</span><span class="pun">);</span><span class="pln">

  </span><span class="com">//存储 KeyStore 对象</span><span class="pln">
  java</span><span class="pun">.</span><span class="pln">io</span><span class="pun">.</span><span class="typ">FileOutputStream</span><span class="pln"> fos </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">null</span><span class="pun">;</span><span class="pln">
  fos </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> java</span><span class="pun">.</span><span class="pln">io</span><span class="pun">.</span><span class="typ">FileOutputStream</span><span class="pun">(</span><span class="str">"newKeyStoreName"</span><span class="pun">);</span><span class="pln">
  keyStore</span><span class="pun">.</span><span class="pln">store</span><span class="pun">(</span><span class="pln">fos</span><span class="pun">,</span><span class="pln"> password</span><span class="pun">);</span><span class="pln">
  
  </span><span class="com">//创建 KeyStore.SecretKeyEntry 对象</span><span class="pln">
  </span><span class="typ">SecretKeyEntry</span><span class="pln"> secretKeyEnt </span><span class="pun">=</span><span class="pln"> </span><span class="pun">(</span><span class="typ">SecretKeyEntry</span><span class="pun">)</span><span class="pln">keyStore</span><span class="pun">.</span><span class="pln">getEntry</span><span class="pun">(</span><span class="str">"secretKeyAlias"</span><span class="pun">,</span><span class="pln"> protectionParam</span><span class="pun">);</span><span class="pln">

  </span><span class="com">//创建 SecretKey 对象</span><span class="pln">
  </span><span class="typ">SecretKey</span><span class="pln"> mysecretKey </span><span class="pun">=</span><span class="pln"> secretKeyEnt</span><span class="pun">.</span><span class="pln">getSecretKey</span><span class="pun">();</span><span class="pln">      
  </span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Algorithm used to generate key : "</span><span class="pun">+</span><span class="pln">mysecretKey</span><span class="pun">.</span><span class="pln">getAlgorithm</span><span class="pun">());</span><span class="pln">   
  </span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Format used for the key: "</span><span class="pun">+</span><span class="pln">mysecretKey</span><span class="pun">.</span><span class="pln">getFormat</span><span class="pun">());</span><span class="pln">

}
}

上面的程序生成以下输出-

Algorithm used to generate key: DSA
Format of the key: RAW

无涯教程-Java加密 - 获取密钥