Example usage for org.bouncycastle.crypto.engines AESEngine processBlock

Introduction

In this page you can find the example usage for org.bouncycastle.crypto.engines AESEngine processBlock.

Prototype

public int processBlock(byte[] in, int inOff, byte[] out, int outOff) 

Source Link

Usage

From source file:io.warp10.script.lora.LORAENC.java

License:Apache License

@Override
public Object apply(WarpScriptStack stack) throws WarpScriptException {

    Object top = stack.pop();//from  ww  w.  ja v  a2  s.  c  o  m

    if (!(top instanceof String)) {
        throw new WarpScriptException(getName() + " expects a 128 bits hex encoded key on top of the stack.");
    }

    String keystr = top.toString();

    if (keystr.length() != 32) {
        throw new WarpScriptException(getName() + " expects a 128 bits hex encoded key on top of the stack.");
    }

    top = stack.pop();

    if (!(top instanceof Long)) {
        throw new WarpScriptException(getName() + " expects a sequence counter below the key.");
    }

    int sequenceCounter = ((Number) top).intValue();

    top = stack.pop();

    if (!(top instanceof Long)) {
        throw new WarpScriptException(
                getName() + " expects a direction (0 uplink or 1 downlink) below the sequence counter.");
    }

    int dir = ((Number) top).intValue();

    if (0 != dir && 1 != dir) {
        throw new WarpScriptException(
                getName() + " expects a direction (0 uplink or 1 downlink) below the sequence counter.");
    }

    top = stack.pop();

    if (!(top instanceof Long)) {
        throw new WarpScriptException(getName() + " expects a device address below the direction.");
    }

    int addr = ((Number) top).intValue();

    String datastr = stack.pop().toString();

    if (0 != datastr.length() % 2) {
        throw new WarpScriptException(
                getName() + " expects a hex encoded data frame with an even length of hex digits.");
    }

    byte[] data = Hex.decode(datastr);

    //
    // Compute MIC block B0
    //

    byte[] ABlock = new byte[16];

    ABlock[0] = 0x01;
    ABlock[5] = (byte) (dir & 0x1);
    ABlock[6] = (byte) (addr & 0xFF);
    ABlock[7] = (byte) ((addr >> 8) & 0xFF);
    ABlock[8] = (byte) ((addr >> 16) & 0xFF);
    ABlock[9] = (byte) ((addr >> 24) & 0xFF);

    ABlock[10] = (byte) ((sequenceCounter) & 0xFF);
    ABlock[11] = (byte) ((sequenceCounter >> 8) & 0xFF);
    ABlock[12] = (byte) ((sequenceCounter >> 16) & 0xFF);
    ABlock[13] = (byte) ((sequenceCounter >> 24) & 0xFF);

    int nblocks = data.length / 16 + (0 == data.length % 16 ? 0 : 1);

    AESEngine aes = new AESEngine();
    KeyParameter key = new KeyParameter(Hex.decode(keystr));
    aes.init(true, key);

    byte[] SBlock = new byte[16];

    int offset = 0;

    for (int i = 0; i < nblocks; i++) {
        ABlock[15] = (byte) (i & 0xFF);
        aes.reset();
        aes.processBlock(ABlock, 0, SBlock, 0);

        for (int k = 0; i < 16; i++) {
            if (offset + k < data.length) {
                data[offset + k] = (byte) (data[offset + k] ^ SBlock[k]);
            }
        }
        offset += 16;
    }

    stack.push(new String(Hex.encode(data), Charsets.US_ASCII));

    return stack;
}

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