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package org.openslx.encryption;
import java.security.InvalidKeyException;
import java.security.InvalidParameterException;
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
public class AsymEncryptionHandler
{
private static final Logger LOG = LogManager.getLogger( AsymEncryptionHandler.class );
private final Key key;
/**
* Create a handler.
*/
public AsymEncryptionHandler( Key key )
{
this.key = key;
}
/**
* Encrypt given plain text message with the key this class was
* instantiated with.
*
* @param cleartext a clear text message
* @return The encrypted message
*/
public byte[] encryptMessage( byte[] cleartext )
{
try {
Cipher cipher = Cipher.getInstance( "RSA" );
cipher.init( Cipher.ENCRYPT_MODE, key );
return cipher.doFinal( cleartext );
} catch ( NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException e ) {
LOG.warn( "Cannot encrypt message", e );
}
return null;
}
/**
* Verify an encrypted message, where we know the plain text.
*
* @param encryptedMessage
* @param expectedCleartext
* @return true if the message matches the expected plain text after decrypting
*/
public boolean verifyMessage( byte[] encryptedMessage, byte[] expectedCleartext )
{
try {
Cipher cipher = Cipher.getInstance( "RSA" );
cipher.init( Cipher.DECRYPT_MODE, key );
byte[] result = cipher.doFinal( encryptedMessage );
return Arrays.equals( expectedCleartext, result );
} catch ( NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException e ) {
LOG.warn( "Cannot verify message", e );
}
return false;
}
/**
* Generate a fresh RSA key pair.
*
* @param bits length of key
* @return key pair, or null on error
*/
public static KeyPair generateKeyPair( int bits )
{
try {
KeyPairGenerator kpg = KeyPairGenerator.getInstance( "RSA" );
kpg.initialize( bits );
return kpg.genKeyPair();
} catch ( NoSuchAlgorithmException | InvalidParameterException e ) {
LOG.warn( "Cannot generate RSA Keypair", e );
return null;
}
}
}
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