DerInputStream (JSS: Java Security Services)

java.lang.Object
- org.mozilla.jss.netscape.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.

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

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`int`	`available()` Returns the number of bytes available for reading.
`byte[]`	`getBitString()` Get a bit string from the input stream.
`java.lang.String`	`getBMPString()`
`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.
`java.lang.String`	`getDirectoryString()`
`java.util.Date`	`getGeneralizedTime()` Get a Generalized encoded time value from the input stream.
`java.lang.String`	`getIA5String()`
`BigInt`	`getInteger()` Get an (unsigned) integer from the input stream.
`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.lang.String`	`getPrintableString()`
`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()`
`BitArray`	`getUnalignedBitString()` Get a bit string from the input stream.
`java.lang.String`	`getUniversalString()`
`java.util.Date`	`getUTCTime()` Get a UTC encoded time value from the input stream.
`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.
`void`	`skipSequence(int startLen)`
`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

- 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.

Class DerInputStream

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

DerInputStream

DerInputStream

Method Detail

subStream

toByteArray

getInteger

getBitString

getUnalignedBitString

getOctetString

getBytes

getNull

getOID

getSequence

skipSequence

getSet

getSet

readVector

getDerValue

getPrintableString

getT61String

getIA5String

getBMPString

getUniversalString

getDirectoryString

getUTCTime

getGeneralizedTime

peekByte

mark

reset

available