BER_TLV Class Reference

Description

Encapsulation of Basic Encoding Rule: Type, Length, Value (BER-TLV) data structures.

This class implements a BER-TLV structure as per the X.690 standard.

Note that this structure is hierarchical - a BER-TLV object may encode a collection of other BER-TLV structures, or it may encode primitive data.

Additional information may be found at:

• https://en.wikipedia.org/wiki/X.690#BER_encoding
• https://en.wikipedia.org/wiki/Type-length-value

Invariant

Always contains a valid type structure, a valid length structure, and a value field consistent with the type and length.

Thread safety:

• The current version of this class is immutable, and thus fully thread-safe
• Future updates to this class will guarantee safety only to the following level:
  • Concurrent accesses to distinct hierarchies: safe
  • Concurrent accesses to distinct objects within same hierarchy: safe, providing no objects are added to or removed from the hierarchy
  • Concurrent accesses to the same object: unsafe, unless all accesses are read-only (query functions, get(), getPrimitive(), getConstructed())

See also

MRTD_API, which provides API functions utilising this class

Classes
enum	BER_ID_Class
	Representation of the ID class field within BER-TLV structures. More...

Public Member Functions
boolean	constructed ()
	Query whether the stored value is constructed (opposite of primitive()) More...
long	constructedSize ()
	Size in BER-TLV objects of the constructed data, if there is any. More...
boolean	definiteLength ()
	Query whether the stored length for this structure is definite. More...
byte []	get ()
	Extract the data, in raw BER-TLV binary format. More...
BER_TLV []	getConstructed ()
	Copy the constructed data, if there is any. More...
byte []	getPrimitive ()
	Copy the primitive data, if there is any. More...
BER_ID_Class	idClass ()
	Query the type ID class for this structure. More...
long	length ()
	Query the length field for this structure. More...
boolean	primitive ()
	Query whether the stored value is primitive (opposite of constructed()) More...
long	primitiveSize ()
	Size in bytes of the primitive data, if there is any. More...
long	size ()
	Query the overall size of this structure. More...
long	tag ()
	Query the type ID tag for this structure.

Member Function Documentation

constructed()

boolean constructed

(

)

Query whether the stored value is constructed (opposite of primitive())

Returns

True for a constructed BER-TLV; false for a primitive one

constructedSize()

long constructedSize

(

)

Size in BER-TLV objects of the constructed data, if there is any.

Returns

Size of getConstructed() output if this is a constructed BER-TLV; zero for a primitive BER-TLV

definiteLength()

boolean definiteLength

(

)

Query whether the stored length for this structure is definite.

Returns

True if length is definite; false if it is indefinite

get()

byte [] get

(

)

Extract the data, in raw BER-TLV binary format.

Returns

Raw representation of the entire structure, of length equal to the output of size()

getConstructed()

BER_TLV [] getConstructed

(

)

Copy the constructed data, if there is any.

Returns

For constructed BER-TLV objects, this returns a copy of the nested BER-TLV structures, with length given by constructedSize(); for primitive BER-TLV objects it returns an empty list

getPrimitive()

byte [] getPrimitive

(

)

Copy the primitive data, if there is any.

Returns

Copy of the value (content) data if this is a primitive BER-TLV, with length given by the output of primitiveSize(); empty array for a constructed BER-TLV

idClass()

BER_ID_Class idClass

(

)

Query the type ID class for this structure.

Returns

ID class; see BER_ID_Class for details

length()

long length

(

)

Query the length field for this structure.

See also

size() for the full size of the TLV structure

Returns

Stored length (of value field) if definite, or zero if indefinite

primitive()

boolean primitive

(

)

Query whether the stored value is primitive (opposite of constructed())

Returns

True for a primitive BER-TLV, false for a constructed one

primitiveSize()

long primitiveSize

(

)

Size in bytes of the primitive data, if there is any.

Returns

Size of getPrimitive() output if this is a primitive BER-TLV; zero for a constructed BER-TLV

size()

long size

(

)

Query the overall size of this structure.

See also

length() for the stored length field (size of value part of BER-TLV, not including type or length parts)

Returns

Size in bytes - i.e. length of the array returned by get()