所以我想对用户输入内容时创建的文件进行加密,并且在加密之后我想解密该文件。用户创建的文件和加密文件都没有问题,但是当我打开加密文件时,我认为这是错误的,因为它上面写有一些胡言乱语。
package br.com.rsa;
import java.security.*;
import java.io.*;
import java.util.*;
import javax.crypto.*;
public class Geracao {
public static void main(String[] args) throws IOException {
//Gerando um arquivo que será encriptado e descriptografado.
Scanner entrada1 = new Scanner(System.in);
System.out.println("Digite qualquer coisa: ");
String entrada = entrada1.nextLine();
System.out.println("Arquivo criado.");
FileOutputStream saida = new FileOutputStream("arquivo.txt");
PrintStream imprimir = new PrintStream(saida);
System.setOut(imprimir);
System.out.println(entrada);
saida.close();
//Gerando as chaves publica e privada.
try {
KeyPairGenerator chave = KeyPairGenerator.getInstance("RSA");
chave.initialize(1024);
KeyPair chaves = chave.generateKeyPair();
PrivateKey privada = chaves.getPrivate();
PublicKey publica = chaves.getPublic();
Base64.Encoder cripto = Base64.getEncoder();
System.out.println("Chave privada: " + cripto.encodeToString(privada.getEncoded()));
System.out.println("");
System.out.println("Chave publica: " + cripto.encodeToString(publica.getEncoded()));
System.out.println("");
//Salvando as chaves publica e privada.
try (FileOutputStream s_prv = new FileOutputStream("privada" + ".key")){
s_prv.write(chaves.getPrivate().getEncoded());
}
try (FileOutputStream s_pub = new FileOutputStream("publica" + ".key")){
s_pub.write(chaves.getPublic().getEncoded());
}
Criptografar(chaves, null);
//Descriptografar(chaves, null);
}
//Qualquer erro dentro da geração das chaves
catch (Exception e){
System.out.println(e);
}
}
//TODO - Comentario
static private void processFile(Cipher cifra, InputStream entrada_arq_c, OutputStream saida_arq_c){
try {
byte[] ibuf = new byte[1024];
int len;
while ((len = entrada_arq_c.read(ibuf)) != -1) {
byte[] obuf = cifra.update(ibuf, 0, len);
if ( obuf != null ) saida_arq_c.write(obuf);
}
byte[] obuf = cifra.doFinal();
if ( obuf != null ) saida_arq_c.write(obuf);
}
catch(Exception e) {
System.out.println("Problema no manuseio do arquivo.");
}
}
//Metodo para criptografar.
static private void Criptografar(KeyPair chaves, Cipher ci){
try {
PublicKey publica = chaves.getPublic();
Cipher cifra = Cipher.getInstance("RSA");
cifra.init(Cipher.ENCRYPT_MODE, publica);
FileInputStream entrada_arq_c = new FileInputStream("arquivo.txt");
FileOutputStream saida_arq_c = new FileOutputStream("criptografado.txt");
processFile(ci, entrada_arq_c, saida_arq_c);
}
catch(Exception e){
System.out.println("Erro ao criptografar.");
}
}
//Metodo para descriptografar.
static private void Descriptografar(KeyPair chaves, Cipher ci){
try {
PrivateKey privada = chaves.getPrivate();
Cipher cifra = Cipher.getInstance("RSA");
cifra.init(Cipher.DECRYPT_MODE, privada);
FileInputStream entrada_arq_c = new FileInputStream("criptografado.txt");
FileOutputStream saida_arq_c = new FileOutputStream("descriptografado.txt");
processFile(ci, entrada_arq_c, saida_arq_c);
}
catch(Exception e){
System.out.println("Erro ao descriptografar.");
}
}
}
答案 0 :(得分:2)
更新:
RSA并非旨在加密大量数据。在这种情况下, 默认为PKCS#1 v1.5的1024位RSA密钥和填充,他不能 加密超过117个字节的数据。 – James K Polk
这里有很多问题。
首先,将System.out
设置为新流并关闭它。结果,您看不到应用程序的任何响应。
解决方案1:保留默认输出流并将其设置回
PrintStream defaultOutStream = System.out;
PrintStream imprimir = new PrintStream(saida);
System.setOut(imprimir);
System.out.println(entrada);
saida.close();
System.setOut(defaultOutStream);
解决方案2:例如,以不同的方式写入文件
try (FileOutputStream saida = new FileOutputStream("arquivo.txt");){
saida.write(entrada.getBytes(Charset.forName("UTF-8")));
} catch (Exception e){
e.printStackTrace();
}
第二,您有一个例外。您将看到“没有任何问题的arquivo”。修复第一个问题后在控制台中进行操作。但是,如果没有堆栈跟踪,它就没有帮助。您需要更新catch块以打印异常原因。例如:
catch(Exception e) {
e.printStackTrace();
System.out.println("Problema no manuseio do arquivo.");
}
在此之后,您将在控制台中找到异常的名称和发生异常的行号。这是导致输出文件为空的根本原因。
在进一步阅读之前,请尝试查找如何修复nullpointer以及其原因。练习调试!将断点放在导致空指针的行上。
首先,您使用Cipher
作为null
来调用构造函数:
Criptografar(chaves, null);
接下来,您正在创建正确的密码,但是使用旧值仍为null的进程函数进行调用:
static private void Criptografar(KeyPair chaves, Cipher ci){
try {
PublicKey publica = chaves.getPublic();
Cipher cifra = Cipher.getInstance("RSA");
cifra.init(Cipher.ENCRYPT_MODE, publica);
FileInputStream entrada_arq_c = new FileInputStream("arquivo.txt");
FileOutputStream saida_arq_c = new FileOutputStream("criptografado.txt");
processFile(ci, entrada_arq_c, saida_arq_c);
}
catch(Exception e){
System.out.println("Erro ao criptografar.");
}
}
解决方案之一是仅使用正确的参数调用函数:processFile(cifra, entrada_arq_c, saida_arq_c);
一些建议:
Cipher
构造函数中使用Criptografar
参数,请将其删除