CCM Block Mode includes MAC bytes when validating Payload Length

[CipherGato]

Bouncy Castle validates that the payload length is less than the maximum allowed on both encrypt and decrypt operations. On decryption the validation is incorrectly including the appended MAC bytes in the length that is validated. This results in an error when decrypting valid ciphertext.

For Example:

With a 13 byte Nonce the maximum payload size is 65535 bytes. The example below attempts to encrypt and then decrypt a 65535 byte array. The decryption operation will fail with:

Exception in thread "main" java.lang.IllegalStateException: CCM packet too large for choice of q.
	at org.bouncycastle.crypto.modes.CCMBlockCipher.processPacket(Unknown Source)
	at org.bouncycastle.crypto.modes.CCMBlockCipher.doFinal(Unknown Source)
	at org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher$AEADGenericBlockCipher.doFinal(Unknown Source)
	at org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(Unknown Source)
	at java.base/javax.crypto.Cipher.doFinal(Cipher.java:2244)
	at org.example.Main.main(Main.java:20)

import org.bouncycastle.jcajce.spec.AEADParameterSpec;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.security.Security;
import java.security.spec.AlgorithmParameterSpec;

public class Main {
    public static void main(String[] args) throws Exception {
        Security.addProvider(new BouncyCastleProvider());

        final byte[] secretKey = new byte[32];
        final byte[] nonce = new byte[13];

        final byte[] input = new byte[65535];

        final byte[] encrypted = getCipher(Cipher.ENCRYPT_MODE, secretKey, nonce).doFinal(input);
        final byte[] decrypted = getCipher(Cipher.DECRYPT_MODE, secretKey, nonce).doFinal(encrypted);
    }

    private static Cipher getCipher(final int mode, final byte[] secretkey, final byte[] nonce) throws Exception {
        final Cipher cipher = Cipher.getInstance("AES/CCM/NoPadding", "BC");
        final AlgorithmParameterSpec algorithmSpec = new AEADParameterSpec(nonce, 128);
        cipher.init(mode, new SecretKeySpec(secretkey, "AES"), algorithmSpec);
        return cipher;
    }
}

[cipherboy]

This should be fixed in e73dbc5 when the sync happens! Thank you for the report.