com.maverick.ssh.components.standalone
Class AbstractHmac

java.lang.Object
  com.maverick.ssh.components.standalone.AbstractHmac

All Implemented Interfaces:

SshHmac

Direct Known Subclasses:

MD5HMac, MD5HMac96, SHA1HMac, SHA1HMac96

public class AbstractHmac

extends java.lang.Object

implements SshHmac

Data integrity is provided by the SSH Transport Protocol by including with each packet a message authentication code (MAC) that is computed from a shared secret, packet sequence number, and the contents of the packet. This class implements a wrapper around the digests so additional implementations need only concern themselves with the actual digest implementation.

Author:

Lee David Painter

Constructor Summary

AbstractHmac(java.lang.String name, com.maverick.crypto.digests.HMac mac)
Construct an uninitialized MAC

Method Summary

void	generate(long sequenceNo, byte[] data, int offset, int len, byte[] output, int start) Generate a MAC from the data supplied.
java.lang.String	getAlgorithm() Get the algorithm name
int	getMacLength() Get the length of the MAC.
void	init(byte[] keydata) Initialize the MAC
boolean	verify(long sequenceNo, byte[] data, int start, int len, byte[] mac, int offset) Verify a MAC.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractHmac

public AbstractHmac(java.lang.String name,
                    com.maverick.crypto.digests.HMac mac)

Construct an uninitialized MAC

Parameters:

name - the name of the algorithm, for example "hmac-sha1"

mac - a new instance of a digest.

Method Detail

getAlgorithm

public java.lang.String getAlgorithm()

Get the algorithm name

Specified by:

getAlgorithm in interface SshHmac

Returns:

the name supplied during creation of this object.

getMacLength

public int getMacLength()

Get the length of the MAC.

Specified by:

getMacLength in interface SshHmac

Returns:

the length of the digest.

generate

public void generate(long sequenceNo,
                     byte[] data,
                     int offset,
                     int len,
                     byte[] output,
                     int start)

Generate a MAC from the data supplied.

Specified by:

generate in interface SshHmac

Parameters:

sequenceNo - the sequence no of the transport protocol message

data - the data to generate a MAC from

offset - the offset in the data to start

len - the length of data to process

init

public void init(byte[] keydata)
          throws SshException

Initialize the MAC

Specified by:

init in interface SshHmac

Parameters:

keydata - the key data

Throws:

java.io.IOException

SshException

verify

public boolean verify(long sequenceNo,
                      byte[] data,
                      int start,
                      int len,
                      byte[] mac,
                      int offset)

Verify a MAC.

Specified by:

verify in interface SshHmac

Parameters:

sequenceNo - the sequence no of the transport protocol message

data - the data including the mac to verify

start - the start of the data

len - the length of the data

Returns:

true if the MAC is corrent, otherwise false

Throws:

java.io.IOException