Change data type of auth challenge from string to byte array, add message verifier that will use private/public keypair directly

1 files changed, 89 insertions, 0 deletions

diff --git a/src/main/java/org/openslx/encryption/AsymEncryptionHandler.java b/src/main/java/org/openslx/encryption/AsymEncryptionHandler.java
new file mode 100644
index 0000000..98109f2
--- /dev/null
+++ b/src/main/java/org/openslx/encryption/AsymEncryptionHandler.java
@@ -0,0 +1,89 @@
+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.log4j.Logger;
+
+public class AsymEncryptionHandler
+{
+	private static final Logger LOG = Logger.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;
+		}
+	}
+
+}