DHSessionKeyBuilder (I2P Anonymous Network - Java Documentation

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

All Methods Instance Methods Concrete Methods
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)

Class DHSessionKeyBuilder

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

DHSessionKeyBuilder

DHSessionKeyBuilder

Method Detail

getMyPublicValue

getMyPublicValueBytes

setPeerPublicValue

setPeerPublicValue

getPeerPublicValue

getPeerPublicValueBytes

getSessionKey

getExtraBytes