# Class ChannelBinding

java.lang.Object
org.ietf.jgss.ChannelBinding

public class ChannelBinding extends Object
This class encapsulates the concept of caller-provided channel binding information. Channel bindings are used to strengthen the quality with which peer entity authentication is provided during context establishment. They enable the GSS-API callers to bind the establishment of the security context to relevant characteristics like addresses or to application specific data.

The caller initiating the security context must determine the appropriate channel binding values to set in the GSSContext object. The acceptor must provide an identical binding in order to validate that received tokens possess correct channel-related characteristics.

Use of channel bindings is optional in GSS-API. ChannelBinding can be set for the `GSSContext` using the `setChannelBinding` method before the first call to `initSecContext` or `acceptSecContext` has been performed. Unless the `setChannelBinding` method has been used to set the ChannelBinding for a GSSContext object, `null` ChannelBinding will be assumed.

Conceptually, the GSS-API concatenates the initiator and acceptor address information, and the application supplied byte array to form an octet string. The mechanism calculates a MIC over this octet string and binds the MIC to the context establishment token emitted by `initSecContext` method of the `GSSContext` interface. The same bindings are set by the context acceptor for its `GSSContext` object and during processing of the `acceptSecContext` method a MIC is calculated in the same way. The calculated MIC is compared with that found in the token, and if the MICs differ, accept will throw a `GSSException` with the major code set to `BAD_BINDINGS`, and the context will not be established. Some mechanisms may include the actual channel binding data in the token (rather than just a MIC); applications should therefore not use confidential data as channel-binding components.

Individual mechanisms may impose additional constraints on addresses that may appear in channel bindings. For example, a mechanism may verify that the initiator address field of the channel binding contains the correct network address of the host system. Portable applications should therefore ensure that they either provide correct information for the address fields, or omit setting of the addressing information.

Since:
  1.4

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ChannelBinding(byte[] appData)`
  Creates a ChannelBinding object without any addressing information.
  `ChannelBinding(InetAddress initAddr, InetAddress acceptAddr, byte[] appData)`
  Create a ChannelBinding object with user supplied address information and data.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `equals(Object obj)`
  Compares two instances of ChannelBinding.
  `InetAddress`
  `getAcceptorAddress()`
  Get the acceptor's address for this channel binding.
  `byte[]`
  `getApplicationData()`
  Get the application specified data for this channel binding.
  `InetAddress`
  `getInitiatorAddress()`
  Get the initiator's address for this channel binding.
  `int`
  `hashCode()`
  Returns a hashcode value for this ChannelBinding object.

  ### Methods declared in class Object

  `clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### ChannelBinding

    public ChannelBinding(InetAddress initAddr, InetAddress acceptAddr, byte[] appData)
    Create a ChannelBinding object with user supplied address information and data. `null` values can be used for any fields which the application does not want to specify.
    Parameters:
      `initAddr` - the address of the context initiator. `null` value can be supplied to indicate that the application does not want to set this value.
      `acceptAddr` - the address of the context acceptor. `null` value can be supplied to indicate that the application does not want to set this value.
      `appData` - application supplied data to be used as part of the channel bindings. `null` value can be supplied to indicate that the application does not want to set this value.

  - ### ChannelBinding

    public ChannelBinding(byte[] appData)
    Creates a ChannelBinding object without any addressing information.
    Parameters:
      `appData` - application supplied data to be used as part of the channel bindings.

- ## Method Details

  - ### getInitiatorAddress

    public InetAddress getInitiatorAddress()
    Get the initiator's address for this channel binding.
    Returns:
      the initiator's address. `null` is returned if the address has not been set.

  - ### getAcceptorAddress

    public InetAddress getAcceptorAddress()
    Get the acceptor's address for this channel binding.
    Returns:
      the acceptor's address. null is returned if the address has not been set.

  - ### getApplicationData

    public byte[] getApplicationData()
    Get the application specified data for this channel binding.
    Returns:
      the application data being used as part of the ChannelBinding. `null` is returned if no application data has been specified for the channel binding.

  - ### equals

    public boolean equals(Object obj)
    Compares two instances of ChannelBinding.
    Overrides:
      `equals` in class `Object`
    Parameters:
      `obj` - another ChannelBinding to compare this one with
    Returns:
      true if the two ChannelBinding's contain the same values for the initiator and acceptor addresses and the application data.
    See Also:
      - `Object.hashCode()`
      - `HashMap`

  - ### hashCode

    public int hashCode()
    Returns a hashcode value for this ChannelBinding object.
    Overrides:
      `hashCode` in class `Object`
    Returns:
      a hashcode value for this ChannelBinding object
    See Also:
      - `Object.equals(java.lang.Object)`
      - `System.identityHashCode(Object)`