This class is a base class for new GSS token definitions, as defined in RFC 4121, that pertain to per-message GSS-API calls. Conceptually GSS-API has two types of per-message tokens: WrapToken and MicToken. They differ in the respect that a WrapToken carries additional plaintext or ciphertext application data besides just the sequence number and checksum. This class encapsulates the commonality in the structure of the WrapToken and the MicToken. This structure can be represented as:

Wrap Tokens

    Octet no   Name        Description
   ---------------------------------------------------------------
     0..1     TOK_ID     Identification field.  Tokens emitted by
                         GSS_Wrap() contain the hex value 05 04
                         expressed in big-endian order in this field.
     2        Flags      Attributes field, as described in section
                         4.2.2.
     3        Filler     Contains the hex value FF.
     4..5     EC         Contains the "extra count" field, in big-
                         endian order as described in section 4.2.3.
     6..7     RRC        Contains the "right rotation count" in big
                         endian order, as described in section 4.2.5.
     8..15    SND_SEQ    Sequence number field in clear text,
                         expressed in big-endian order.
     16..last Data       Encrypted data for Wrap tokens with
                         confidentiality, or plaintext data followed
                         by the checksum for Wrap tokens without
                         confidentiality, as described in section
                         4.2.4.
MIC Tokens

    Octet no   Name        Description
    -----------------------------------------------------------------
     0..1     TOK_ID     Identification field.  Tokens emitted by
                         GSS_GetMIC() contain the hex value 04 04
                         expressed in big-endian order in this field.
     2        Flags      Attributes field, as described in section
                         4.2.2.
     3..7     Filler     Contains five octets of hex value FF.
     8..15    SND_SEQ    Sequence number field in clear text,
                         expressed in big-endian order.
     16..last SGN_CKSUM  Checksum of the "to-be-signed" data and
                         octet 0..15, as described in section 4.2.4.

This class is the super class of WrapToken_v2 and MicToken_v2. The token's header (bytes[0..15]) and data (byte[16..]) are saved in tokenHeader and tokenData fields. Since there is no easy way to find out the exact length of a WrapToken_v2 token from any header info, in the case of reading from stream, we read all available() bytes into the token.

All read actions are performed in this super class. On the write part, the super class only write the tokenHeader, and the content writing is inside child classes.