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import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.MessageDigest;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;
public class MainClass {
public static void main(String[] args) throws Exception{
Cipher cipher = createCipher(Cipher.ENCRYPT_MODE);
applyCipher("file_to_encrypt", "encrypted_file", cipher);
cipher = createCipher(Cipher.DECRYPT_MODE);
applyCipher("file_to_decrypt", "decrypted_file", cipher);
}
static Cipher createCipher(int mode) throws Exception {
PBEKeySpec keySpec = new PBEKeySpec("test".toCharArray());
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
SecretKey key = keyFactory.generateSecret(keySpec);
MessageDigest md = MessageDigest.getInstance("MD5");
md.update("input".getBytes());
byte[] digest = md.digest();
byte[] salt = new byte[8];
for (int i = 0; i < 8; ++i)
salt[i] = digest[i];
PBEParameterSpec paramSpec = new PBEParameterSpec(salt, 20);
Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
cipher.init(mode, key, paramSpec);
return cipher;
}
static void applyCipher(String inFile, String outFile, Cipher cipher) throws Exception {
CipherInputStream in = new CipherInputStream(new FileInputStream(inFile), cipher);
BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outFile));
int BUFFER_SIZE = 8;
byte[] buffer = new byte[BUFFER_SIZE];
int numRead = 0;
do {
numRead = in.read(buffer);
if (numRead > 0)
out.write(buffer, 0, numRead);
} while (numRead == 8);
}
}
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