Java安全（JCA/JSSE）：非对称加密和数字摘要
读一个流这个buffer到底设置多大？你根本就不会知道
所以用下面的方法
privatestaticvoid copyStream(InputStream is,OutputStream os)throws Exception{
byte[] buff=newbyte[1024];
inttotal=0;
int len=is.read(buff);
while(len!=-1){
os.write(buff, 0, len);
len=is.read(buff);
}
或者
byte[] src=newbyte[fisDat.available()];//对于文件流来说就是其长度，而对于像网络流就不是了
int len=fisDat.read(src);
int total=0;
while(total<src.length){
total+=len;
len=fisDat.read(src, total, src.length-total);
}
公钥加密私钥解密
package com.xiongshiyan.security;
importjava.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
importjava.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import javax.crypto.Cipher;
importjavax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
importjavax.crypto.NoSuchPaddingException;
publicclass PublicSecretTest {
/**
* @param args
* @throws Exception
*/
publicstaticvoid main(String[] args)throws Exception {
//TODO Auto-generatedmethod stub
PublicSecretTest.publicEnrypt();
PublicSecretTest.privateDerypt2();
}
privatestaticvoid publicEnrypt()throws Exception{
Cipher cipher = Cipher.getInstance("RSA");
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
KeyPair keyPair = keyPairGenerator.generateKeyPair();
PublicKey publicKey=keyPair.getPublic();
PrivateKey privateKey=keyPair.getPrivate();
cipher.init(Cipher.ENCRYPT_MODE, publicKey);//使用公钥加密
byte[] secResult = cipher.doFinal("熊诗言".getBytes());
System.out.println(new String(secResult));
//把加密后的数据和key一起给别人 别人拿到了之后进行恢复
ObjectOutputStream oosKey=new ObjectOutputStream(new FileOutputStream("key2.key"));
oosKey.writeObject(privateKey);//写入加密key
oosKey.close();
FileOutputStream oosDat=new FileOutputStream("dat2.dat");
oosDat.write(secResult);//写入加密dat
oosDat.close();
}
privatestaticvoidprivateDerypt() throws Exception{
ObjectInputStream oisKey=new ObjectInputStream(new FileInputStream("key2.key"));
Key key=(Key)oisKey.readObject();
oisKey.close();
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, key);
FileInputStream fisDat=new FileInputStream("dat2.dat");
/* ByteArrayOutputStream baos=new ByteArrayOutputStream();
SecretKeyTest.copyStream(fisDat,baos);
byte[] deSecResult=cipher.doFinal(baos.toByteArray());*/
byte[] src=newbyte[fisDat.available()];//对于文件流来说就是其长度，而对于像网络流就不是了
int len=fisDat.read(src);
int total=0;
while(total<src.length){
total+=len;
len=fisDat.read(src, total, src.length-total);
}
byte[] deSecResult=cipher.doFinal(src);
System.out.println(new String(deSecResult));
}
privatestaticvoid privateDerypt2()throws Exception{
ObjectInputStream oisKey=new ObjectInputStream(new FileInputStream("key2.key"));
Key key=(Key)oisKey.readObject();
oisKey.close();
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, key);
FileInputStream fisDat=new FileInputStream("dat2.dat");
/* ByteArrayOutputStream baos=new ByteArrayOutputStream();
SecretKeyTest.copyStream(fisDat,baos);
byte[] deSecResult=cipher.doFinal(baos.toByteArray());*/
/*byte[]src=newbyte[fisDat.available()];//对于文件流来说就是其长度，而对于像网络流就不是了
int len=fisDat.read(src);
int total=0;
while(total<src.length){
total+=len;
len=fisDat.read(src, total,src.length-total);
}
byte[] deSecResult=cipher.doFinal(src);
System.out.println(new String(deSecResult,"utf-8"));*/
//使用CipherInputStream,在读的过程中解密
/*CipherInputStreamcipherInputStream=new CipherInputStream(fisDat,cipher);
ByteArrayOutputStream baos=new ByteArrayOutputStream();
PublicSecretTest.copyStream(cipherInputStream,baos);
baos.close();
cipherInputStream.close();
System.out.println(new String(baos.toByteArray(),"utf-8"));*/
//使用CipherOutputStream//在写的时候解密
CipherOutputStream cipherOutputStream=new CipherOutputStream(System.out,cipher);
PublicSecretTest.copyStream(fisDat,cipherOutputStream);
cipherOutputStream.close();
fisDat.close();
}
privatestaticvoid copyStream(InputStream is,OutputStream os) throws Exception{
byte[] buff=newbyte[1024];
inttotal=0;
int len=is.read(buff);
while(len!=-1){
os.write(buff, 0, len);
len=is.read(buff);
}
}
}
数字摘要：就是数据的指纹，任何两个数据的指纹都不一样，并且都是128位的
一般下载的文件使用一个工具算出它的md5码与给你的比较，如果一样表示没有被破坏
数据校验
数据库密码
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
//数据库中存储md5，你给密码，算出md5，如果一样就能验证成功，防止内鬼
//md5();
mac();
}
private static void md5() throws NoSuchAlgorithmException {
MessageDigest digest = MessageDigest.getInstance("md5");
digest.update("xiongshiyan".getBytes());//这个得update就好使了
byte[] result=digest.digest();
System.out.println(result.length);//16个字节
System.out.println(new String(result));
System.out.println(toHex(result));
}
private static String toHex(byte[] buff){
StringBuilder stringBuilder = new StringBuilder();
for(int i=0;i<buff.length;i++){
int hi=(buff[i]>>4)&0x0f;
int lo=buff[i]&0x0f;
stringBuilder.append(hi>9?(char)((hi-10)+'A'):(char)(hi+'0'));
stringBuilder.append(lo>9?(char)((lo-10)+'A'):(char)(lo+'0'));
}
return stringBuilder.toString();
}
//这种算法使用原始数据和密码一起进行摘要，可以防止内容和摘要一同被篡改
private static void mac() throws Exception{
PBEKeySpec keySpec = new PBEKeySpec("abcdef".toCharArray());
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
SecretKey key = keyFactory.generateSecret(keySpec);
Mac mac = Mac.getInstance("HmacMD5");
mac.init(key);
byte[] src = "data".getBytes();
byte[] dest = mac.doFinal(src);
System.out.println(dest.length);
System.out.println(toHex(dest));
}