status-keycard-java/lib/src/main/java/im/status/keycard/applet/Pairing.java

package im.status.keycard.applet;

import org.bouncycastle.util.encoders.Base64;

import java.util.Arrays;

/**
 * Stores pairing information.
 */
public class Pairing {
  private byte[] pairingKey;
  private byte pairingIndex;

  /**
   * Constructor. The pairingKey and pairingIndex are those generated at the end of a successful pairing.
   * @param pairingKey the pairing key
   * @param pairingIndex the pairing index
   */
  public Pairing(byte[] pairingKey, byte pairingIndex) {
    this.pairingKey = pairingKey;
    this.pairingIndex = pairingIndex;
  }

  /**
   * Constructor. Initializes from a byte array previously generated from the toByteArray method
   * @param fromByteArray the result of a previous toByteArray invocation
   */
  public Pairing(byte[] fromByteArray) {
    pairingIndex = fromByteArray[0];
    pairingKey = Arrays.copyOfRange(fromByteArray, 1, fromByteArray.length);
  }

  /**
   * Constructor. Initializes from a String previously generated from the toBase64 method
   * @param base64 the result of a previous toBase64 invocation
   */
  public Pairing(String base64) {
    this(Base64.decode(base64));
  }

  public byte[] getPairingKey() {
    return pairingKey;
  }

  public byte getPairingIndex() {
    return pairingIndex;
  }

  public byte[] toByteArray() {
    byte[] res = new byte[pairingKey.length + 1];
    res[0] = pairingIndex;
    System.arraycopy(pairingKey, 0, res, 1, pairingKey.length);

    return res;
  }

  public String toBase64() {
    return Base64.toBase64String(toByteArray());
  }
}