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1. 瀵煎叆蹇呰鐨勭被鍜屽寘锛?/li>

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Security;
import javax.crypto.Cipher;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

2. 娣诲姞Bouncy Castle浣滀负JCA鐨勬彁渚涜€咃細

Security.addProvider(new BouncyCastleProvider());

3. 鐢熸垚RSA瀵嗛挜瀵癸細

KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA", "BC");
keyGen.initialize(2048);
KeyPair keyPair = keyGen.generateKeyPair();
PrivateKey privateKey = keyPair.getPrivate();
PublicKey publicKey = keyPair.getPublic();

4. 鍔犲瘑鏂囦欢锛?/li>

Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", "BC");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
FileInputStream inputFile = new FileInputStream("input.txt");
FileOutputStream outputFile = new FileOutputStream("encrypted.txt");
byte[] inputBytes = new byte[245];
int bytesRead;
while ((bytesRead = inputFile.read(inputBytes)) != -1) {
    byte[] outputBytes = cipher.doFinal(inputBytes, 0, bytesRead);
    outputFile.write(outputBytes);
}

5. 瑙ｅ瘑鏂囦欢锛?/li>

cipher.init(Cipher.DECRYPT_MODE, privateKey);
inputFile = new FileInputStream("encrypted.txt");
outputFile = new FileOutputStream("decrypted.txt");
byte[] encryptedBytes = new byte[256];
while ((bytesRead = inputFile.read(encryptedBytes)) != -1) {
    byte[] decryptedBytes = cipher.doFinal(encryptedBytes, 0, bytesRead);
    outputFile.write(decryptedBytes);
}

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