Retrieving Public Key

Nitrokeys Misc
1

Hi
I’m creating a Java project that is simply based on a client that sends a string to a server.
The server receives it and encrypts/decrypts the data using Private and Public keys generated on the Nitrokey HSM device. I’m using the SunPKCS11 as provider.

When i want to encrypt I use the Private key and it works fine but when i want to decrypt using the Public key it gives me an error like this:

java.security.InvalidKeyException: init() failed
at sun.security.pkcs11.P11RSACipher.implInit(P11RSACipher.java:239)
at sun.security.pkcs11.P11RSACipher.engineInit(P11RSACipher.java:168)
at javax.crypto.Cipher.init(Cipher.java:1249)
at javax.crypto.Cipher.init(Cipher.java:1189)
at CriptographyServer.main(CriptographyServer.java:116)
Caused by: sun.security.pkcs11.wrapper.PKCS11Exception: CKR_FUNCTION_NOT_SUPPORTED
at sun.security.pkcs11.wrapper.PKCS11.C_VerifyRecoverInit(Native Method)
at sun.security.pkcs11.P11RSACipher.initialize(P11RSACipher.java:310)
at sun.security.pkcs11.P11RSACipher.implInit(P11RSACipher.java:237)
… 4 more

This is the code for getting keys:

                    KeyPairGenerator gen = KeyPairGenerator.getInstance("RSA", hsmProvider);
		gen.initialize(2048);
				
		KeyPair pair = gen.generateKeyPair();

		Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", hsmProvider);
		cipher.init(Cipher.ENCRYPT_MODE, pair.getPrivate());
		
		byte[] msg = cipher.doFinal(recivedMessage.getBytes());
		String enc = bytesToHex(msg);
		
		System.out.println("Crypting..." + recivedMessage + "\nCrypted Message...: " + enc);	
		
		cipher.init(Cipher.DECRYPT_MODE, pair.getPublic());
		byte[] msg1 = cipher.doFinal(msg);
		String dec = bytesToHex(msg1);
		System.out.println("Decrypted Message..." +  dec);

So i think the “pair.getPublic()” is wrong for retrieving the public key…

2

Hi A-User22,
It looks like you have it the wrong way: using RSA, you are meant to encrypt with the public key, and decrypt with the private (secret) key, and you are trying to do the opposite.

3

Yeah, I’ve tried doing like you said but the problem remain. I think the problem it’s how I get the public key.