Package net.i2p.router.transport.crypto

Class DHSessionKeyBuilder

java.lang.Object

net.i2p.router.transport.crypto.DHSessionKeyBuilder

public class DHSessionKeyBuilder
extends Object

Generate a new session key through a diffie hellman exchange. This uses the constants defined in CryptoConstants, which causes the exchange to create a 256 bit session key. This class precalcs a set of values on its own thread. Whenever the pool has less than the minimum, it fills it up again to the max. There is a delay after each precalculation so that the CPU isn't hosed during startup. These three parameters are controlled by java environmental variables and can be adjusted via: -Dcrypto.dh.precalc.min=40 -Dcrypto.dh.precalc.max=100 -Dcrypto.dh.precalc.delay=60000 (delay is milliseconds) To disable precalculation, set min to 0

Since:

0.9 moved from net.i2p.crypto

Author:

jrandom

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	DHSessionKeyBuilder.Factory
static class	DHSessionKeyBuilder.InvalidPublicParameterException
static class	DHSessionKeyBuilder.PrecalcRunner	Try to keep DH pairs at the ready.

Constructor Summary

Constructors

Constructor	Description
DHSessionKeyBuilder()	Create a new public/private value pair for the DH exchange.
DHSessionKeyBuilder(I2PAppContext ctx)	Create a new public/private value pair for the DH exchange.

Method Summary

Modifier and Type	Method	Description
ByteArray	getExtraBytes()	Retrieve the extra bytes beyond the session key resulting from the DH exchange.
BigInteger	getMyPublicValue()	Retrieve the public value used by the local participant in the DH exchange,
byte[]	getMyPublicValueBytes()	Return a 256 byte representation of our public key, with leading 0s if necessary.
BigInteger	getPeerPublicValue()
byte[]	getPeerPublicValueBytes()	Return a 256 byte representation of his public key, with leading 0s if necessary.
SessionKey	getSessionKey()	Retrieve the session key, calculating it if necessary (and if possible).
void	setPeerPublicValue(byte[] val)
void	setPeerPublicValue(BigInteger peerVal)	Specify the value given by the peer for use in the session key negotiation

Methods inherited from class java.lang.Object

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

Constructor Detail

DHSessionKeyBuilder

DHSessionKeyBuilder()

Create a new public/private value pair for the DH exchange. Only for internal use and unit tests. Others should get instances from PrecalcRunner.getBuilder()

DHSessionKeyBuilder

DHSessionKeyBuilder(I2PAppContext ctx)

Create a new public/private value pair for the DH exchange. Only for internal use and unit tests. Others should get instances from PrecalcRunner.getBuilder()

Method Detail

getMyPublicValue

public BigInteger getMyPublicValue()

Retrieve the public value used by the local participant in the DH exchange,

getMyPublicValueBytes

public byte[] getMyPublicValueBytes()

Return a 256 byte representation of our public key, with leading 0s if necessary.

setPeerPublicValue

public void setPeerPublicValue(BigInteger peerVal)
                        throws DHSessionKeyBuilder.InvalidPublicParameterException

Specify the value given by the peer for use in the session key negotiation

Throws:

IllegalStateException - if already set

DHSessionKeyBuilder.InvalidPublicParameterException

setPeerPublicValue

public void setPeerPublicValue(byte[] val)
                        throws DHSessionKeyBuilder.InvalidPublicParameterException

Parameters:

val - 256 bytes

Throws:

DHSessionKeyBuilder.InvalidPublicParameterException

getPeerPublicValue

public BigInteger getPeerPublicValue()

getPeerPublicValueBytes

public byte[] getPeerPublicValueBytes()

Return a 256 byte representation of his public key, with leading 0s if necessary.

getSessionKey

public SessionKey getSessionKey()

Retrieve the session key, calculating it if necessary (and if possible).

Returns:

session key exchanged, or null if the exchange is not complete

getExtraBytes

public ByteArray getExtraBytes()

Retrieve the extra bytes beyond the session key resulting from the DH exchange. If there aren't enough bytes (with all of them being consumed by the 32 byte key), the SHA256 of the key itself is used - but that won't ever happen. Used only by UDP. getData() will be non-null and have at least 32 bytes after call to getSessionKey()

Returns:

non-null (but rv.getData() may be null)