org.tomitribe.churchkey.asn1

Class DerParser

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

org.tomitribe.churchkey.asn1.DerParser

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class DerParser
extends java.io.FilterInputStream

A bare minimum DER parser - just enough to be able to decode signatures and private keys

Author:

Apache MINA SSHD Project

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_DER_VALUE_LENGTH Maximum size of data allowed by readLength() - it is a bit arbitrary since one can encode 32-bit length data, but it is good enough for the keys

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor and Description
DerParser(byte... bytes)
DerParser(byte[] bytes, int offset, int len)
DerParser(java.io.InputStream s)

Method Summary

Modifier and Type	Method and Description
java.math.BigInteger	readBigInteger()
int	readLength() Decode the length of the field.
Asn1Object	readObject()
DerParser	readSequence()

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, read, read, read, reset, skip

Methods inherited from class java.lang.Object

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

Field Detail

MAX_DER_VALUE_LENGTH

public static final int MAX_DER_VALUE_LENGTH

Maximum size of data allowed by readLength() - it is a bit arbitrary since one can encode 32-bit length data, but it is good enough for the keys

See Also:

Constant Field Values

Constructor Detail

DerParser

public DerParser(byte... bytes)

DerParser

public DerParser(byte[] bytes,
                 int offset,
                 int len)

DerParser

public DerParser(java.io.InputStream s)

Method Detail

readLength

public int readLength()
               throws java.io.IOException

Decode the length of the field. Can only support length encoding up to 4 octets. In BER/DER encoding, length can be encoded in 2 forms:

• Short form - One octet. Bit 8 has value "0" and bits 7-1 give the length.

• Long form - Two to 127 octets (only 4 is supported here). Bit 8 of first octet has value "1" and bits 7-1 give the number of additional length octets. Second and following octets give the length, base 256, most significant digit first.

Returns:

The length as integer

Throws:

java.io.IOException - If invalid format found

readSequence

public DerParser readSequence()
                       throws java.io.IOException

Throws:

java.io.IOException

readObject

public Asn1Object readObject()
                      throws java.io.IOException

Throws:

java.io.IOException

readBigInteger

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

Throws:

java.io.IOException