Package com.github.toolarium.security.pki.impl.rsa.der

Class DERInputStream

java.lang.Object

com.github.toolarium.security.pki.impl.rsa.der.DERInputStream

public class DERInputStream
extends 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.

Constructor Summary

Constructors

Constructor	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.
DERInputStream(DERInputBuffer buf)	Constructor for DERInputStream

Method Summary

Modifier and Type	Method	Description
int	available()	Returns the number of bytes available for reading.
byte[]	getBitString()	Get a bit string from the input stream.
String	getBMPString()	Read a string that was encoded as a BMPString DER value.
int	getByte()	Get a byte from the input stream.
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.
BigInt	getEnumerated()	Get an enumerated from the input stream.
Date	getGeneralizedTime()	Get a generalized encoded time value from the input stream.
String	getIA5String()	Read a string that was encoded as a IA5tring DER value.
BigInt	getInteger()	Get an (unsigned) integer from the input stream.
int	getLength()	Gets the length
static int	getLength(int lenByte, InputStream in)	Get a length from the input stream, allowing for at most 32 bits of encoding to be used.
static int	getLength(InputStream in)	Get a length from the input stream, allowing for at most 32 bits of encoding to be used.
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.
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.
String	getT61String()	Read a string that was encoded as a T61String DER value.
BitArray	getUnalignedBitString()	Get a bit string from the input stream.
Date	getUTCTime()	Get a UTC encoded time value from the input stream.
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()	Peek a byte
protected DERValue[]	readVector(int startLen)	Read a "vector" of values ...
void	reset()	Return to the position of the last mark call.
DERInputStream	subStream(int len, boolean doSkip)	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

Constructor Details

DERInputStream

public DERInputStream(byte[] data)

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)

DERInputStream

public DERInputStream(byte[] data,
 int offset,
 int len)

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"

DERInputStream

public DERInputStream(DERInputBuffer buf)

Constructor for DERInputStream

Parameters:

buf - the buffer

Method Details

subStream

public DERInputStream subStream(int len,
 boolean doSkip)
                         throws 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.

doSkip - 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.

Returns:

the stream

Throws:

IOException - in case of error

toByteArray

public byte[] toByteArray()

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

Returns:

the array

getInteger

public BigInt getInteger()
                  throws IOException

Get an (unsigned) integer from the input stream.

Returns:

the integer

Throws:

IOException - in case of error

getEnumerated

public BigInt getEnumerated()
                     throws IOException

Get an enumerated from the input stream.

Returns:

the integer

Throws:

IOException - in case of error

getBitString

public byte[] getBitString()
                    throws IOException

Get a bit string from the input stream. Only octet-aligned bitstrings (multiples of eight bits in length) are handled by this method.

Returns:

the array

Throws:

IOException - in case of error

getUnalignedBitString

public BitArray getUnalignedBitString()
                               throws IOException

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

Returns:

the array

Throws:

IOException - in case of error

getOctetString

public byte[] getOctetString()
                      throws IOException

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

Returns:

the array

Throws:

IOException - in case of error

getBytes

public void getBytes(byte[] val)
              throws IOException

Returns the asked number of bytes from the input stream.

Parameters:

val - the array

Throws:

IOException - in case of error

getNull

public void getNull()
             throws IOException

Reads an encoded null value from the input stream.

Throws:

IOException - in case of error

getOID

public ObjectIdentifier getOID()
                        throws IOException

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

Returns:

the id

Throws:

IOException - in case of error

getSequence

public DERValue[] getSequence(int startLen)
                       throws 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:

IOException - in case of error

getSet

public DERValue[] getSet(int startLen)
                  throws 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:

IOException - in case of error

getSet

public DERValue[] getSet(int startLen,
 boolean implicit)
                  throws 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:

IOException - in case of error

readVector

protected DERValue[] readVector(int startLen)
                         throws IOException

Read a "vector" of values ... set or sequence have the same encoding, except for the initial tag, so both use this same helper routine.

Parameters:

startLen - the start length

Returns:

the DERValue's

Throws:

IOException - In case of a data error

getDERValue

public DERValue getDERValue()
                     throws 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.

Returns:

the value

Throws:

IOException - in case of error

getUTF8String

public String getUTF8String()
                     throws IOException

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

Returns:

the string

Throws:

IOException - in case of error

getPrintableString

public String getPrintableString()
                          throws IOException

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

Returns:

the string

Throws:

IOException - in case of error

getT61String

public String getT61String()
                    throws IOException

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

Returns:

the string

Throws:

IOException - in case of error

getIA5String

public String getIA5String()
                    throws IOException

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

Returns:

the string

Throws:

IOException - in case of error

getBMPString

public String getBMPString()
                    throws IOException

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

Returns:

the string

Throws:

IOException - in case of error

getUTCTime

public Date getUTCTime()
                throws IOException

Get a UTC encoded time value from the input stream.

Returns:

the date

Throws:

IOException - in case of error

getGeneralizedTime

public Date getGeneralizedTime()
                        throws IOException

Get a generalized encoded time value from the input stream.

Returns:

the date

Throws:

IOException - in case of error

mark

public void mark(int value)

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

Parameters:

value - the value

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.

Returns:

the available bytes

peekByte

public int peekByte()
             throws IOException

Peek a byte

Returns:

the byte

Throws:

IOException - in case of error

getByte

public int getByte()

Get a byte from the input stream.

Returns:

a byte

getLength

public int getLength()
              throws IOException

Gets the length

Returns:

the length

Throws:

IOException - in case of error

getLength

public static int getLength(InputStream in)
                     throws IOException

Get a length from the input stream, allowing for at most 32 bits of encoding to be used. (Not the same as getting a tagged integer!)

Parameters:

in - the input stream

Returns:

the length or -1 if indefinite length found.

Throws:

IOException - on parsing error or unsupported lengths.

getLength

public static int getLength(int lenByte,
 InputStream in)
                     throws IOException

Get a length from the input stream, allowing for at most 32 bits of encoding to be used. (Not the same as getting a tagged integer!)

Parameters:

lenByte - the length

in - the input stream

Returns:

the length or -1 if indefinite length found.

Throws:

IOException - on parsing error or unsupported lengths.