我正在阅读一篇关于使用私钥进行加密的IBM教程。我编写了如下代码
import java.security.*;
import javax.crypto.*;
// encrypt and decrypt using the DES private key algorithm
public class PrivateExample {
public static void main (String[] args) throws Exception {
String text=new String();
text="THIS IS AN ENCRYPTION TEST";
byte[] plainText = text.getBytes("UTF8");
// get a DES private key
System.out.println( "\nStart generating DES key" );
KeyGenerator keyGen = KeyGenerator.getInstance("DES");
keyGen.init(56);
Key key = keyGen.generateKey();
System.out.println( "Finish generating DES key" );
// get a DES cipher object and print the provider
Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
System.out.println( "\n" + cipher.getProvider().getInfo() );
//
// encrypt using the key and the plaintext
System.out.println( "\nStart encryption" );
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] cipherText = cipher.doFinal(plainText);
System.out.println( "Finish encryption: " );
System.out.println( new String(cipherText, "UTF8") );
//
// decrypt the ciphertext using the same key
System.out.println( "\nStart decryption" );
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] newPlainText = cipher.doFinal(cipherText);
System.out.println( "Finish decryption: " );
System.out.println( new String(newPlainText, "UTF8") );
}
}
以上代码效果很好。我能够看到结果和一切。但我想修改它如下,以便我可以将cipherText存储在一个文件中。然后另一个程序从文件中读取加密文本并对其进行解密。以下是我到目前为止所做的事情,但我无法理解如何继续。稍微提示如何继续将有所帮助。
import java.security.*;
import javax.crypto.*;
// encrypt and decrypt using the DES private key algorithm
public class PrivateExample {
public static void main (String[] args) throws Exception {
String text=new String();
text="This is an encryption test";
byte[] plainText = text.getBytes("UTF8");
// get a DES private key
System.out.println( "\nStart generating DES key" );
KeyGenerator keyGen = KeyGenerator.getInstance("DES");
keyGen.init(56);
Key key = keyGen.generateKey();
System.out.println( "Finish generating DES key" );
//
// get a DES cipher object and print the provider
Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
System.out.println( "\n" + cipher.getProvider().getInfo() );
//
// encrypt using the key and the plaintext
System.out.println( "\nStart encryption" );
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] cipherText = cipher.doFinal(plainText);
System.out.println( "Finish encryption: " );
System.out.println( new String(cipherText, "UTF8") );
//Now writing to an ouput file the cipherText
try{
FileOutputStream fs=new FileOutputStream("c:/test.txt");
fs.write(cipherText);
}catch(Exception e){
e.printStackTrace();
}
//How to proceed from here
}
}
现在这个程序的工作已经完成。它已成功将加密的字符串写入文件。新程序只需要解密数据。如何从文件中读取加密的字节?新程序显然不知道原始字符串是什么,但我将使用与算法中相同的密钥。请帮忙!我是加密新手
答案 0 :(得分:3)
以下是将密钥写入文件的方法:
//Write your key to an output file.
byte[] keyAsByte = key.getEncoded();
FileOutputStream keyfos = new FileOutputStream("key.txt");
keyfos.write(keyAsByte);
keyfos.close();
我不建议将带有加密文本的密钥放在同一个文件中。
以下是您阅读ecrypted文本以及密钥和解密的方法:
//Read your key
FileInputStream keyFis = new FileInputStream("key.txt");
byte[] encKey = new byte[keyFis.available()];
keyFis.read(encKey);
keyFis.close();
Key keyFromFile = new SecretKeySpec(encKey, "DES");
//Read your text
FileInputStream encryptedTextFis = new FileInputStream("test.txt");
byte[] encText = new byte[encryptedTextFis.available()];
encryptedTextFis.read(encText);
encryptedTextFis.close();
//Decrypt
Cipher decrypter = Cipher.getInstance("DES/ECB/PKCS5Padding");
decrypter.init(Cipher.DECRYPT_MODE, keyFromFile);
byte[] decryptedText = decrypter.doFinal(encText);
//Print result
System.out.println("Decrypted Text: " + new String(decryptedText));
注意:我没有使用与您相同的路径来撰写信息。