sun.security.util

Class DerInputStream

java.lang.Object

sun.security.util.DerInputStream

public class DerInputStream
extends java.lang.Object

A DER input stream, used for parsing ASN.1 DER-encoded data such as that found in X.509 certificates. DER is a subset of BER/1, which has the advantage that it allows only a single encoding of primitive data. (High level data such as dates still support many encodings.) That is, it uses the "Definite" Encoding Rules (DER) not the "Basic" ones (BER).

Note that, like BER/1, DER streams are streams of explicitly tagged data values. Accordingly, this programming interface does not expose any variant of the java.io.InputStream interface, since that kind of input stream holds untagged data values and using that I/O model could prevent correct parsing of the DER data.

At this time, this class supports only a subset of the types of DER data encodings which are defined. That subset is sufficient for parsing most X.509 certificates.

Author:

David Brownell, Amit Kapoor, Hemma Prafullchandra

Field Summary

Fields

Modifier and Type	Field and Description
byte	tag The DER tag of the value; one of the tag_ constants.

Constructor Summary

Constructors

Constructor and Description
DerInputStream(byte[] data) Create a DER input stream from a data buffer.
DerInputStream(byte[] data, int offset, int len) Create a DER input stream from part of a data buffer.

Method Summary

Methods

Modifier and Type	Method and Description
int	available() Returns the number of bytes available for reading.
java.math.BigInteger	getBigInteger() Get a integer from the input stream as a BigInteger object.
byte[]	getBitString() Get a bit string from the input stream.
java.lang.String	getBMPString() Read a string that was encoded as a BMPString DER value.
void	getBytes(byte[] val) Returns the asked number of bytes from the input stream.
DerValue	getDerValue() Get a single DER-encoded value from the input stream.
int	getEnumerated() Get an enumerated from the input stream.
java.util.Date	getGeneralizedTime() Get a Generalized encoded time value from the input stream.
java.lang.String	getGeneralString() Read a string that was encoded as a GeneralString DER value.
java.lang.String	getIA5String() Read a string that was encoded as a IA5tring DER value.
int	getInteger() Get an integer from the input stream as an integer.
void	getNull() Reads an encoded null value from the input stream.
byte[]	getOctetString() Returns an ASN.1 OCTET STRING from the input stream.
ObjectIdentifier	getOID() Reads an X.200 style Object Identifier from the stream.
java.math.BigInteger	getPositiveBigInteger() Returns an ASN.1 INTEGER value as a positive BigInteger.
java.lang.String	getPrintableString() Read a string that was encoded as a PrintableString DER value.
DerValue[]	getSequence(int startLen) Return a sequence of encoded entities.
DerValue[]	getSet(int startLen) Return a set of encoded entities.
DerValue[]	getSet(int startLen, boolean implicit) Return a set of encoded entities.
java.lang.String	getT61String() Read a string that was encoded as a T61String DER value.
BitArray	getUnalignedBitString() Get a bit string from the input stream.
java.util.Date	getUTCTime() Get a UTC encoded time value from the input stream.
java.lang.String	getUTF8String() Read a string that was encoded as a UTF8String DER value.
void	mark(int value) Mark the current position in the buffer, so that a later call to reset will return here.
int	peekByte()
protected DerValue[]	readVector(int startLen)
void	reset() Return to the position of the last mark call.
DerInputStream	subStream(int len, boolean do_skip) Creates a new DER input stream from part of this input stream.
byte[]	toByteArray() Return what has been written to this DerInputStream as a byte array.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

tag

public byte tag

The DER tag of the value; one of the tag_ constants.

Constructor Detail

DerInputStream

public DerInputStream(byte[] data)
               throws java.io.IOException

Create a DER input stream from a data buffer. The buffer is not copied, it is shared. Accordingly, the buffer should be treated as read-only.

Parameters:

data - the buffer from which to create the string (CONSUMED)

Throws:

java.io.IOException

DerInputStream

public DerInputStream(byte[] data,
              int offset,
              int len)
               throws java.io.IOException

Create a DER input stream from part of a data buffer. The buffer is not copied, it is shared. Accordingly, the buffer should be treated as read-only.

Parameters:

data - the buffer from which to create the string (CONSUMED)

offset - the first index of data which will be read as DER input in the new stream

len - how long a chunk of the buffer to use, starting at "offset"

Throws:

java.io.IOException

Method Detail

subStream

public DerInputStream subStream(int len,
                       boolean do_skip)
                         throws java.io.IOException

Creates a new DER input stream from part of this input stream.

Parameters:

len - how long a chunk of the current input stream to use, starting at the current position.

do_skip - true if the existing data in the input stream should be skipped. If this value is false, the next data read on this stream and the newly created stream will be the same.

Throws:

java.io.IOException

toByteArray

public byte[] toByteArray()

Return what has been written to this DerInputStream as a byte array. Useful for debugging.

getInteger

public int getInteger()
               throws java.io.IOException

Get an integer from the input stream as an integer.

Returns:

the integer held in this DER input stream.

Throws:

java.io.IOException

getBigInteger

public java.math.BigInteger getBigInteger()
                                   throws java.io.IOException

Get a integer from the input stream as a BigInteger object.

Returns:

the integer held in this DER input stream.

Throws:

java.io.IOException

getPositiveBigInteger

public java.math.BigInteger getPositiveBigInteger()
                                           throws java.io.IOException

Returns an ASN.1 INTEGER value as a positive BigInteger. This is just to deal with implementations that incorrectly encode some values as negative.

Returns:

the integer held in this DER value as a BigInteger.

Throws:

java.io.IOException

getEnumerated

public int getEnumerated()
                  throws java.io.IOException

Get an enumerated from the input stream.

Returns:

the integer held in this DER input stream.

Throws:

java.io.IOException

getBitString

public byte[] getBitString()
                    throws java.io.IOException

Get a bit string from the input stream. Padded bits (if any) will be stripped off before the bit string is returned.

Throws:

java.io.IOException

getUnalignedBitString

public BitArray getUnalignedBitString()
                               throws java.io.IOException

Get a bit string from the input stream. The bit string need not be byte-aligned.

Throws:

java.io.IOException

getOctetString

public byte[] getOctetString()
                      throws java.io.IOException

Returns an ASN.1 OCTET STRING from the input stream.

Throws:

java.io.IOException

getBytes

public void getBytes(byte[] val)
              throws java.io.IOException

Returns the asked number of bytes from the input stream.

Throws:

java.io.IOException

getNull

public void getNull()
             throws java.io.IOException

Reads an encoded null value from the input stream.

Throws:

java.io.IOException

getOID

public ObjectIdentifier getOID()
                        throws java.io.IOException

Reads an X.200 style Object Identifier from the stream.

Throws:

java.io.IOException

getSequence

public DerValue[] getSequence(int startLen)
                       throws java.io.IOException

Return a sequence of encoded entities. ASN.1 sequences are ordered, and they are often used, like a "struct" in C or C++, to group data values. They may have optional or context specific values.

Parameters:

startLen - guess about how long the sequence will be (used to initialize an auto-growing data structure)

Returns:

array of the values in the sequence

Throws:

java.io.IOException

getSet

public DerValue[] getSet(int startLen)
                  throws java.io.IOException

Return a set of encoded entities. ASN.1 sets are unordered, though DER may specify an order for some kinds of sets (such as the attributes in an X.500 relative distinguished name) to facilitate binary comparisons of encoded values.

Parameters:

startLen - guess about how large the set will be (used to initialize an auto-growing data structure)

Returns:

array of the values in the sequence

Throws:

java.io.IOException

getSet

public DerValue[] getSet(int startLen,
                boolean implicit)
                  throws java.io.IOException

Return a set of encoded entities. ASN.1 sets are unordered, though DER may specify an order for some kinds of sets (such as the attributes in an X.500 relative distinguished name) to facilitate binary comparisons of encoded values.

Parameters:

startLen - guess about how large the set will be (used to initialize an auto-growing data structure)

implicit - if true tag is assumed implicit.

Returns:

array of the values in the sequence

Throws:

java.io.IOException

readVector

protected DerValue[] readVector(int startLen)
                         throws java.io.IOException

Throws:

java.io.IOException

getDerValue

public DerValue getDerValue()
                     throws java.io.IOException

Get a single DER-encoded value from the input stream. It can often be useful to pull a value from the stream and defer parsing it. For example, you can pull a nested sequence out with one call, and only examine its elements later when you really need to.

Throws:

java.io.IOException

getUTF8String

public java.lang.String getUTF8String()
                               throws java.io.IOException

Read a string that was encoded as a UTF8String DER value.

Throws:

java.io.IOException

getPrintableString

public java.lang.String getPrintableString()
                                    throws java.io.IOException

Read a string that was encoded as a PrintableString DER value.

Throws:

java.io.IOException

getT61String

public java.lang.String getT61String()
                              throws java.io.IOException

Read a string that was encoded as a T61String DER value.

Throws:

java.io.IOException

getIA5String

public java.lang.String getIA5String()
                              throws java.io.IOException

Read a string that was encoded as a IA5tring DER value.

Throws:

java.io.IOException

getBMPString

public java.lang.String getBMPString()
                              throws java.io.IOException

Read a string that was encoded as a BMPString DER value.

Throws:

java.io.IOException

getGeneralString

public java.lang.String getGeneralString()
                                  throws java.io.IOException

Read a string that was encoded as a GeneralString DER value.

Throws:

java.io.IOException

getUTCTime

public java.util.Date getUTCTime()
                          throws java.io.IOException

Get a UTC encoded time value from the input stream.

Throws:

java.io.IOException

getGeneralizedTime

public java.util.Date getGeneralizedTime()
                                  throws java.io.IOException

Get a Generalized encoded time value from the input stream.

Throws:

java.io.IOException

peekByte

public int peekByte()
             throws java.io.IOException

Throws:

java.io.IOException

mark

public void mark(int value)

Mark the current position in the buffer, so that a later call to reset will return here.

reset

public void reset()

Return to the position of the last mark call. A mark is implicitly set at the beginning of the stream when it is created.

available

public int available()

Returns the number of bytes available for reading. This is most useful for testing whether the stream is empty.