java对asn.1格式数据编解码示例

深碍√TFBOYSˉ_ 2023-03-14 05:26 180阅读 0赞

工作中用到了asn.1格式数据，所以这里对asn.1格式的编解码做一个简单的介绍，主要通过程序来构建与解析asn.1格式数据。asn.1格式一般分为三个部分，分别是类型、长度、值，也就是Tag,Length,Value，简称TLV格式。

类型一般分为以下几种：

sequence，也叫集合和结构

integer，整数

utf8string，字符串

boolean，布尔类型

time，时间类型

下面构建一个maven项目，引入项目依赖：

<dependency>
        <groupId>org.bouncycastle</groupId>
        <artifactId>bcprov-ext-jdk15on</artifactId>
        <version>1.65</version>
    </dependency>

定义一个student的实体类，继承ASN1Object：

package com.xxx.asn1;
    
    import org.bouncycastle.asn1.ASN1EncodableVector;
    import org.bouncycastle.asn1.ASN1Integer;
    import org.bouncycastle.asn1.ASN1Object;
    import org.bouncycastle.asn1.ASN1Primitive;
    import org.bouncycastle.asn1.DERSequence;
    import org.bouncycastle.asn1.DERUTF8String;
    import org.bouncycastle.asn1.x509.Time;
    
    public class Student extends ASN1Object {
    	
    	private ASN1Integer id;
    	private DERUTF8String name;
    	private ASN1Integer age;
    	private Time createDate;
    	
    	public void setId(ASN1Integer id) {
    		this.id = id;
    	}
    	public void setName(DERUTF8String name) {
    		this.name = name;
    	}
    	public void setAge(ASN1Integer age) {
    		this.age = age;
    	}
    	public void setCreateDate(Time createDate) {
    		this.createDate = createDate;
    	}
    	
    	public ASN1Integer getId() {
    		return id;
    	}
    	public DERUTF8String getName() {
    		return name;
    	}
    	public ASN1Integer getAge() {
    		return age;
    	}
    	public Time getCreateDate() {
    		return createDate;
    	}
    	
    	public Student() {
    		// TODO Auto-generated constructor stub
    	}
    	
    	
    
    	public Student(ASN1Integer id, DERUTF8String name, ASN1Integer age,
    			Time createDate) {
    		super();
    		this.id = id;
    		this.name = name;
    		this.age = age;
    		this.createDate = createDate;
    	}
    	
    	@Override
    	public ASN1Primitive toASN1Primitive() {
    		ASN1EncodableVector vector = new ASN1EncodableVector();
    		vector.add(id);
    		vector.add(name);
    		vector.add(age);
    		vector.add(createDate);
    		return new DERSequence(vector);
    	}
    
    }

定义一个主类App，来分别构建asn.1和解析asn.1格式数据：

package com.xxx.asn1;
    
    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.OutputStream;
    import java.util.Date;
    
    import org.bouncycastle.asn1.ASN1Encodable;
    import org.bouncycastle.asn1.ASN1InputStream;
    import org.bouncycastle.asn1.ASN1Integer;
    import org.bouncycastle.asn1.ASN1Primitive;
    import org.bouncycastle.asn1.ASN1Sequence;
    import org.bouncycastle.asn1.ASN1SequenceParser;
    import org.bouncycastle.asn1.DERUTF8String;
    import org.bouncycastle.asn1.x509.Time;
    import org.bouncycastle.util.encoders.Base64;
    
    public class App {
    	
    	/**
    	 * 构建asn.1
    	 */
    	public static void buildStudent(){
    		Integer id = 1;
        	String name = "buejee";
        	Integer age = 18;
        	Time createDate = new Time(new Date());
        	try {
    			
        		Student student = new Student(new ASN1Integer(id),
        				new DERUTF8String(name),
        				new ASN1Integer(age),
        				createDate);
        		String data = Base64.toBase64String(student.getEncoded());
        		System.out.println(data);
        		OutputStream out = new FileOutputStream(new File("student.cer"));
        		out.write(data.getBytes());
        		out.flush();
        		out.close();
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    	
    	/**
    	 * 解析asn.1
    	 */
    	public static void resolveStudent(){
    		byte[] data = Base64.decode("MB0CAQEMBmJ1ZWplZQIBEhcNMjAwNTE1MTUxNDAzWg==");
    		ASN1InputStream ais = new ASN1InputStream(data);
    		ASN1Primitive primitive = null;
    		try {
    			while((primitive=ais.readObject())!=null){
    				System.out.println("sequence->"+primitive);
    				if(primitive instanceof ASN1Sequence){
    					ASN1Sequence sequence = (ASN1Sequence)primitive;
    					ASN1SequenceParser parser = sequence.parser();
    					ASN1Encodable encodable = null;
    					while((encodable=parser.readObject())!=null){
    						primitive = encodable.toASN1Primitive();
    						System.out.println("prop->"+primitive);
    					}
    				}
    			}
    		} catch (Exception e) {
    			e.printStackTrace();
    		}finally{
    			try {
    				ais.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    	}
    	
        public static void main( String[] args ){
        	//buildStudent();
        	resolveStudent();
        }
    }

分别运行两个方法，第一个是buildStudent()是构建一个asn.1格式数据，我们最后将他转为base64字符串，打印并存储在student.cer文件中。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70][]

打印的结果和保存在student.cer中的结果是一样的。我们可以通过asn1view工具查看这个内容：

sequence部分：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 1][]

第一个integer:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 2][]

string:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 3][]

第二个integer:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 4][]

time :

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 5][]

这所有的内容都符合我们在代码中定义的数据：

![20200515235729127.png][]

id=1,name=buejee,age=18,createDate=(20)20/05/15 15:36:43,时间是世界时间，所以东八区的话应该是(20)20/05/15 23:36:43，都是正确的。

我们再来看看解析，调用resolveStudent()方法，控制台打印结果如下：

![2020051600011121.png][]

数据读出来了。跟我们构建时传入的参数一样。

本文的代码和工具asn1view都会放到[github][]上，有需要的可以查看。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70]: /images/20230312/81963fb726454c818ee49777bc83ccfe.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 1]: /images/20230312/149395c839c54d619853a13a547885b6.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 2]: /images/20230312/9e06a5d5e1cd43358813ca580008a97a.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 3]: /images/20230312/a4374e29bd83495ba996b35f879a43f2.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 4]: /images/20230312/e307d4fea2f94d318c381738f5603485.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 5]: /images/20230312/d1e13dade3da4e1aa89584d48c0cb08d.png
[20200515235729127.png]: /images/20230312/988fb54b416145549d2934e62adbddb3.png
[2020051600011121.png]: /images/20230312/864f8ed082594469965423c5d22ad9a0.png
[github]: https://github.com/buejee/asn1demo