Example usage for org.bouncycastle.crypto.macs GMac getMacSize

Introduction

In this page you can find the example usage for org.bouncycastle.crypto.macs GMac getMacSize.

Prototype

public int getMacSize() 

Source Link

Usage

From source file:org.openmuc.jdlms.internal.security.HlsProcessorGmac.java

License:Open Source License

@Override
public byte[] process(byte[] challenge, byte[] authenticationKey, byte[] encryptionKey, byte[] systemTitle,
        int frameCounter) throws IOException, UnsupportedOperationException {

    byte[] sc = new byte[] { 0x10 };
    byte[] frameCounterBytes = ByteBuffer.allocate(4).putInt(frameCounter).array();
    byte[] iv = ByteBuffer.allocate(systemTitle.length + frameCounterBytes.length).put(systemTitle)
            .put(frameCounterBytes).array();

    CipherParameters cipherParameters = new KeyParameter(encryptionKey);
    ParametersWithIV parameterWithIV = new ParametersWithIV(cipherParameters, iv);

    GMac mac = new GMac(new GCMBlockCipher(new AESFastEngine()), 96);

    mac.init(parameterWithIV);//from w  ww .ja  v a  2 s .co  m

    byte[] input = ByteBuffer.allocate(sc.length + authenticationKey.length + challenge.length).put(sc)
            .put(authenticationKey).put(challenge).array();
    mac.update(input, 0, input.length);
    final byte[] generatedMac = new byte[mac.getMacSize()];
    mac.doFinal(generatedMac, 0);

    return ByteBuffer.allocate(sc.length + frameCounterBytes.length + generatedMac.length).put(sc)
            .put(frameCounterBytes).put(generatedMac).array();
}

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