| Код |
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import java.io.*;
import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;
/*Пример использования алгоритма шифрования RSA
java RSATest -genkey public privatte
java RSATest -encrypt plaintext encrypted public
java RSAText -decrypt encrypted decrypted private*/
public class RSATest
{
public static void main(String[] args)
{
try
{
if(args[0].equals("-genkey"))
{
KeyPairGenerator pairgen=KeyPairGenerator.getInstance("RSA");
SecureRandom random=new SecureRandom();
pairgen.initialize(KEYSIZE, random);
KeyPair keyPair=pairgen.generateKeyPair();
ObjectOutputStream out=new ObjectOutputStream(new FileOutputStream(args[1]));
out.writeObject(keyPair.getPublic());
out.close();
out=new ObjectOutputStream(new FileOutputStream(args[2]));
out.writeObject(keyPair.getPrivate());
out.close();
}
else
if(args[0].equals("-encrypt"))
{
Security.addProvider(new BouncyCastleProvider());
KeyGenerator keygen=KeyGenerator.getInstance("DES");
SecureRandom random=new SecureRandom();
keygen.init(random);
SecretKey key=keygen.generateKey();
//Свертывание с помощью открытого ключа RSA
ObjectInputStream keyIn=new ObjectInputStream(new FileInputStream(args[3]));
Key publicKey=(Key) keyIn.readObject();
keyIn.close();
Cipher cipher=Cipher.getInstance("RSA","BC");
cipher.init(Cipher.WRAP_MODE,publicKey);
byte[] wrappedKey=cipher.wrap(key);
DataOutputStream out=new DataOutputStream(new FileOutputStream(args[2]));
out.writeInt(wrappedKey.length);
out.write(wrappedKey);
InputStream in=new FileInputStream(args[1]);
cipher=Cipher.getInstance("DES");
cipher.init(Cipher.ENCRYPT_MODE,key);
crypt(in,out,cipher);
in.close();
out.close();
}
else
{
DataInputStream in=new DataInputStream(new FileInputStream(args[1]));
int length=in.readInt();
byte[] wrappedKey=new byte[length];
in.read(wrappedKey,0,length);
//Развертывание с помщью открытого ключа RSA
ObjectInputStream keyIn=new ObjectInputStream(new FileInputStream(args[3]));
Key privateKey=(Key) keyIn.readObject();
keyIn.close();
Cipher cipher=Cipher.getInstance("RSA","BC");
cipher.init(Cipher.UNWRAP_MODE,privateKey);
Key key=cipher.unwrap(wrappedKey,"DES",Cipher.SECRET_KEY);
OutputStream out=new FileOutputStream(args[2]);
cipher=Cipher.getInstance("DES","BC");
cipher.init(Cipher.DECRYPT_MODE,key);
crypt(in,out,cipher);
in.close();
out.close();
}
}
catch(IOException exception)
{
exception.printStackTrace();
}
catch(GeneralSecurityException exception)
{
exception.printStackTrace();
}
catch(ClassNotFoundException exception)
{
exception.printStackTrace();
}
}
public static void crypt(InputStream in,OutputStream out,Cipher cipher) throws IOException, GeneralSecurityException
{
int blockSize=cipher.getBlockSize();
int outputSize=cipher.getOutputSize(blockSize);
byte[] inBytes=new byte[blockSize];
byte[] outBytes=new byte[outputSize];
int inLength=0;
boolean more=true;
while(more)
{
inLength=in.read(inBytes);
if(inLength==blockSize)
{
int outLength=cipher.update(inBytes,0,blockSize,outBytes);
out.write(outBytes,0,outLength);
}
else more=false;
}
if(inLength>0)
outBytes=cipher.doFinal(inBytes,0,inLength);
else
outBytes=cipher.doFinal();
out.write(outBytes);
}
public static final int KEYSIZE=512;
}
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Взято из книжки |
