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Class netscape.security.util.DerInputStream
netscape.security.util.DerInputStream
- public class DerInputStream
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.
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DerInputStream(byte[])
- Create a DER input stream from a data buffer.
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DerInputStream(byte[], int, int)
- Create a DER input stream from part of a data buffer.
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available()
- Returns the number of bytes available for reading.
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getBitString()
- Get a bit string from the input stream.
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getBMPString()
-
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getBytes(byte[])
- Returns the asked number of bytes from the input stream.
-
getDerValue()
- Get a single DER-encoded value from the input stream.
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getGeneralizedTime()
- Get a Generalized encoded time value from the input stream.
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getIA5String()
-
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getInteger()
- Get an (unsigned) integer from the input stream.
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getNull()
- Reads an encoded null value from the input stream.
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getOctetString()
- Returns an ASN.1 OCTET STRING from the input stream.
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getOID()
- Reads an X.200 style Object Identifier from the stream.
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getPrintableString()
-
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getSequence(int)
- Return a sequence of encoded entities.
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getSet(int)
- Return a set of encoded entities.
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getSet(int, boolean)
- Return a set of encoded entities.
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getT61String()
-
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getUnalignedBitString()
- Get a bit string from the input stream.
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getUniversalString()
-
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getUTCTime()
- Get a UTC encoded time value from the input stream.
-
mark(int)
- Mark the current position in the buffer, so that
a later call to
reset will return here.
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peekByte()
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readVector(int)
-
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reset()
- Return to the position of the last
mark
call.
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subStream(int, boolean)
- Creates a new DER input stream from part of this input stream.
-
toByteArray()
- Return what has been written to this DerInputStream
as a byte array.
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"
subStream
public DerInputStream subStream(int len,
boolean do_skip) 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.
- 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.
toByteArray
public byte[] toByteArray()
- Return what has been written to this DerInputStream
as a byte array. Useful for debugging.
getInteger
public BigInt getInteger() throws IOException
- Get an (unsigned) integer from the input stream.
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.
getUnalignedBitString
public BitArray getUnalignedBitString() throws IOException
- Get a bit string from the input stream. The bit string need
not be byte-aligned.
getOctetString
public byte[] getOctetString() throws IOException
- Returns an ASN.1 OCTET STRING from the input stream.
getBytes
public void getBytes(byte val[]) throws IOException
- Returns the asked number of bytes from the input stream.
getNull
public void getNull() throws IOException
- Reads an encoded null value from the input stream.
getOID
public ObjectIdentifier getOID() throws IOException
- Reads an X.200 style Object Identifier from the stream.
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
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
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
readVector
protected DerValue[] readVector(int startLen) throws IOException
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.
getPrintableString
public String getPrintableString() throws IOException
getT61String
public String getT61String() throws IOException
getIA5String
public String getIA5String() throws IOException
getBMPString
public String getBMPString() throws IOException
getUniversalString
public String getUniversalString() throws IOException
getUTCTime
public Date getUTCTime() throws IOException
- Get a UTC encoded time value from the input stream.
getGeneralizedTime
public Date getGeneralizedTime() throws IOException
- Get a Generalized encoded time value from the input stream.
peekByte
public int peekByte() throws 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.
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