Class 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.

    Version:
    1.35
    Author:
    David Brownell, Amit Kapoor, Hemma Prafullchandra
    • 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.
    • Constructor Detail

      • 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"
    • 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()
                           throws java.io.IOException
        Return what has been written to this DerInputStream as a byte array. Useful for debugging.
        Throws:
        java.io.IOException
      • getInteger

        public BigInt getInteger()
                          throws java.io.IOException
        Get an (unsigned) integer from the input stream.
        Throws:
        java.io.IOException
      • getBitString

        public byte[] getBitString()
                            throws java.io.IOException
        Get a bit string from the input stream. Only octet-aligned bitstrings (multiples of eight bits in length) are handled by this method.
        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
      • skipSequence

        public void skipSequence​(int startLen)
                          throws java.io.IOException
        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
      • getPrintableString

        public java.lang.String getPrintableString()
                                            throws java.io.IOException
        Throws:
        java.io.IOException
      • getT61String

        public java.lang.String getT61String()
                                      throws java.io.IOException
        Throws:
        java.io.IOException
      • getIA5String

        public java.lang.String getIA5String()
                                      throws java.io.IOException
        Throws:
        java.io.IOException
      • getBMPString

        public java.lang.String getBMPString()
                                      throws java.io.IOException
        Throws:
        java.io.IOException
      • getUniversalString

        public java.lang.String getUniversalString()
                                            throws java.io.IOException
        Throws:
        java.io.IOException
      • getDirectoryString

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