Package opencard.opt.util

Class Tag

  • public class Tag
extends java.lang.Object
    This class represents Tags as defined in the Basic Encoding Rules for ASN.1 defined in ISO 8825. A tag consists of two class bits (0 - 4), a flag indicating wether the TLV is constructed or primitive.

    The encoding is like this (C = class bit, c = composed flag, X = data bit): 

     Range from 0x0 - 0x1E:
 C C c X X X X X
 
    
 Range from 0x1F - 0x80:
 C C c 1 1 1 1 1 0 X X X X X X X
 
    
 Range from 0x81 - 0x4000:
 C C c 1 X X X X 1 X X X X X X X 0 X X X X X X X
 
    
 Range from 0x4001 - 0x200000:
 C C c 1 X X X X 1 X X X X X X X 1 X X X X X X X 0 X X X X X X X
 
    
 Range from 0x200001 - 0x10000000:
 C C c 1 X X X X 1 X X X X X X X 1 X X X X X X X 0 X X X X X X X 0 X X X X X X X
    Author:
    Thomas Schaeck
    See Also:
    TLV

    • Constructor Summary

      Constructors 
      Constructor Description
      Tag()
      Create a null tag.
      Tag​(byte[] binary)  
      Tag​(byte[] binary, int[] offset)
      Create a tag from binary representation.
      Tag​(int tag, byte tagClass, boolean constructed)
      Creates a tag from a given tag value, class and constructed flag.
      Tag​(Tag t)
      Clone a tag.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int code()
      Get the code of the tag.
      boolean equals​(java.lang.Object o)
      Check for equality.
      void fromBinary​(byte[] binary, int[] offset)
      Initialize the Tag object from a BER-coded binary representation.
      byte[] getBytes()
      Gets a byte array representing the tag.
      int hashCode()
      Compute a hash code for this tag.
      boolean isConstructed()
      Check whether this Tag is constructed.
      void set​(int tag, byte tagclass, boolean constructed)
      Set the tag number, class and constructed flag of this Tag to the given values.
      void setConstructed​(boolean constructed)
      Set the constructed flag of this Tag to the given value.
      int size()
      Return the number of bytes which are required to BER-code the tag value.
      void toBinary​(byte[] binary, int[] offset)
      Convert the tag to binary representation.
      java.lang.String toString()
      Get a string representation for this tag.

      • Methods inherited from class java.lang.Object

        clone, finalize, getClass, notify, notifyAll, wait, wait, wait

    • Constructor Detail

      • Tag

        public Tag()
        Create a null tag.

      • Tag

        public Tag​(Tag t)
        Clone a tag.

        Parameters:
        t - The Tag object to be cloned.

      • Tag

        public Tag​(int tag,
           byte tagClass,
           boolean constructed)
        Creates a tag from a given tag value, class and constructed flag.

        Parameters:
        tag - An integer representing the value of the tag.
        tagClass - A byte value representing the class of the tag.
        constructed - A boolean value true signals that the tag is constructed, false signals that the tag is primitive.

      • Tag

        public Tag​(byte[] binary,
           int[] offset)
        Create a tag from binary representation.

        Parameters:
        binary - The byte array from which the tag shall be generated.
        offset - An integer value giving the offset into the the byte array from where to start.

      • Tag

        public Tag​(byte[] binary)

    • Method Detail

      • size

        public int size()
        Return the number of bytes which are required to BER-code the tag value.

        Returns:
        An integer giving the number of bytes.

      • fromBinary

        public void fromBinary​(byte[] binary,
                       int[] offset)
        Initialize the Tag object from a BER-coded binary representation.

        Parameters:
        binary - A byte array containing the BER-coded tag.
        offset - An integer giving an offset into the byte array from where to start.

      • getBytes

        public byte[] getBytes()
        Gets a byte array representing the tag.
        Returns:
        the tag as a byte array

      • toBinary

        public void toBinary​(byte[] binary,
                     int[] offset)
        Convert the tag to binary representation.

        Parameters:
        binary - A byte array to which the BER-coded binary representation of the tag shall be written.
        offset - An integer value giving an offset into the byte array from where to start.

      • set

        public void set​(int tag,
                byte tagclass,
                boolean constructed)
        Set the tag number, class and constructed flag of this Tag to the given values.

        Parameters:
        tag - An integer value giving the tag value.
        tagclass - A byte value giving the class.
        constructed - A boolean representing the constructed flag.

      • setConstructed

        public void setConstructed​(boolean constructed)
        Set the constructed flag of this Tag to the given value.

        Parameters:
        constructed - A boolean representing the constructed flag.

      • code

        public int code()
        Get the code of the tag.

        Returns:
        An integer value representing the tag's code.

      • isConstructed

        public boolean isConstructed()
        Check whether this Tag is constructed.

        Returns:
        true if it is constructed, false otherwise.

      • hashCode

        public int hashCode()
        Compute a hash code for this tag.

        Overrides:
        hashCode in class java.lang.Object
        Returns:
        An integer value representing the hash code.

      • equals

        public boolean equals​(java.lang.Object o)
        Check for equality.

        Overrides:
        equals in class java.lang.Object
        Returns:
        true, if this Tag instance equals the given tag, false otherwise.

      • toString

        public java.lang.String toString()
        Get a string representation for this tag.

        Overrides:
        toString in class java.lang.Object
        Returns:
        The string representation.