org.mozilla.jss.asn1

Class BIT_STRING

Implemented Interfaces:
ASN1Value

public class BIT_STRING
extends java.lang.Object
implements ASN1Value

An ASN.1 BIT STRING, which is an ordered sequence of bits. The bits are stored the same way they are encoded in BER: as an array of bytes with 0-7 unused bits at the end.

Nested Class Summary

static class
BIT_STRING.Template
A class for decoding a BIT_STRING from its BER encoding.

Field Summary

static Form
FORM
static Tag
TAG

Constructor Summary

BIT_STRING(BitSet bs, int numBits)
Constructs a BIT_STRING from a BitSet.
BIT_STRING(byte[] bits, int padCount)

Method Summary

void
encode(OutputStream ostream)
Write this value's DER encoding to an output stream using its own base tag.
void
encode(Tag implicitTag, OutputStream ostream)
Write this value's DER encoding to an output stream using an implicit tag.
byte[]
getBits()
Returns the bits packed into an array of bytes, with padding at the end.
int
getPadCount()
Returns the number of padding bits at the end of the array.
boolean
getRemoveTrailingZeroes()
Determines whether the DER-encoding of this bitstring will have its trailing zeroes removed.
Tag
getTag()
Returns the base tag for this type, not counting any tags that may be imposed on it by its context.
static BIT_STRING.Template
getTemplate()
void
setRemoveTrailingZeroes(boolean removeTrailingZeroes)
Determines whether the DER-encoding of this bitstring will have its trailing zeroes removed.
BitSet
toBitSet()
Copies this BIT STRING into a Java BitSet.
boolean[]
toBooleanArray()
Copies this BIT STRING into a boolean array.

Field Details

FORM

public static final Form FORM


TAG

public static final Tag TAG

Constructor Details

BIT_STRING

public BIT_STRING(BitSet bs,
                  int numBits)
            throws NumberFormatException
Constructs a BIT_STRING from a BitSet.

Parameters:
bs - A BitSet.
numBits - The number of bits to copy from the BitSet. This is necessary because the size of a BitSet is always padded up to a multiple of 64, but not all of these bits may be significant.


BIT_STRING

public BIT_STRING(byte[] bits,
                  int padCount)
            throws NumberFormatException

Parameters:
bits - The bits packed into an array of bytes, with padding at the end. The array may be empty (but not null), in which case padCount must be zero. The array is referenced, not cloned.
padCount - The number of padding bits at the end of the array. Must be in the range [0,7].

Method Details

encode

public void encode(OutputStream ostream)
            throws IOException
Write this value's DER encoding to an output stream using its own base tag.
Specified by:
encode in interface ASN1Value


encode

public void encode(Tag implicitTag,
                   OutputStream ostream)
            throws IOException
Write this value's DER encoding to an output stream using an implicit tag.
Specified by:
encode in interface ASN1Value


getBits

public byte[] getBits()
Returns the bits packed into an array of bytes, with padding at the end. The array may be empty (but not null), in which case padCount must be zero. The array is referenced, not cloned.


getPadCount

public int getPadCount()
Returns the number of padding bits at the end of the array. Must be in the range [0,7].


getRemoveTrailingZeroes

public boolean getRemoveTrailingZeroes()
Determines whether the DER-encoding of this bitstring will have its trailing zeroes removed. Generally, DER requires that trailing zeroes be removed when the bitstring is used to hold flags, but not when it is used to hold binary data (such as a public key). The default is false.


getTag

public Tag getTag()
Returns the base tag for this type, not counting any tags that may be imposed on it by its context.
Specified by:
getTag in interface ASN1Value


getTemplate

public static BIT_STRING.Template getTemplate()


setRemoveTrailingZeroes

public void setRemoveTrailingZeroes(boolean removeTrailingZeroes)
Determines whether the DER-encoding of this bitstring will have its trailing zeroes removed. Generally, DER requires that trailing zeroes be removed when the bitstring is used to hold flags, but not when it is used to hold binary data (such as a public key). The default is false. If this bit string is used to hold flags, you should set this to true.


toBitSet

public BitSet toBitSet()
Copies this BIT STRING into a Java BitSet. Note that BitSet.size() will not accurately reflect the number of bits in the BIT STRING, because the size of a BitSet is always rounded up to the next multiple of 64. The extra bits will be set to 0.


toBooleanArray

public boolean[] toBooleanArray()
Copies this BIT STRING into a boolean array. Each element of the array represents one bit with true for 1 and false for 0.