Package org.apache.sshd.common.util.io.der

Class DERParser

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

org.apache.sshd.common.util.io.der.DERParser

All Implemented Interfaces:

Closeable, AutoCloseable

public class DERParser
extends 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	Description
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

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor	Description
DERParser(byte... bytes)
DERParser(byte[] bytes, int offset, int len)
DERParser(InputStream s)

Method Summary

Modifier and Type	Method	Description
BigInteger	readBigInteger()
int	readLength()	Decode the length of the field.
ASN1Object	readObject()

Methods inherited from class java.io.FilterInputStream

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

Methods inherited from class java.io.InputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo

Methods inherited from class java.lang.Object

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

Field Details

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 Details

DERParser

public DERParser(byte... bytes)

DERParser

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

DERParser

public DERParser(InputStream s)

Method Details

readLength

public int readLength()
               throws 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:

IOException - If invalid format found

readObject

public ASN1Object readObject()
                      throws IOException

Throws:

IOException

readBigInteger

public BigInteger readBigInteger()
                          throws IOException

Throws:

IOException