net.i2p.data.router
Class RouterKeyGenerator

java.lang.Object
  extended by net.i2p.data.RoutingKeyGenerator
      extended by net.i2p.data.router.RouterKeyGenerator

public class RouterKeyGenerator
extends RoutingKeyGenerator

Component to manage the munging of hashes into routing keys - given a hash, perform some consistent transformation against it and return the result. This transformation is fed by the current "mod data". Right now the mod data is the current date (GMT) as a string: "yyyyMMdd", and the transformation takes the original hash, appends the bytes of that mod data, then returns the SHA256 of that concatenation. Do we want this to simply do the XOR of the SHA256 of the current mod data and the key? does that provide the randomization we need? It'd save an SHA256 op. Bah, too much effort to think about for so little gain. Other algorithms may come into play layer on about making periodic updates to the routing key for data elements to mess with Sybil. This may be good enough though. Also - the method generateDateBasedModData() should be called after midnight GMT once per day to generate the correct routing keys!

Since:
0.9.16 moved from net.i2p.data.RoutingKeyGenerator..

Constructor Summary
RouterKeyGenerator(I2PAppContext context)
           
 
Method Summary
 boolean generateDateBasedModData()
          Update the current modifier data with some bytes derived from the current date (yyyyMMdd in GMT)
 long getLastChanged()
          The version of the current (today's) mod data.
 byte[] getModData()
          The current (today's) mod data.
 byte[] getNextModData()
          Tomorrow's mod data.
 Hash getNextRoutingKey(Hash origKey)
          Get the routing key using tomorrow's modData, not today's
 Hash getRoutingKey(Hash origKey)
          Generate a modified (yet consistent) hash from the origKey by generating the SHA256 of the targetKey with the current modData appended to it This makes Sybil's job a lot harder, as she needs to essentially take over the whole keyspace.
 long getTimeTillMidnight()
          How long until midnight (ms)
 
Methods inherited from class net.i2p.data.RoutingKeyGenerator
getInstance
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

RouterKeyGenerator

public RouterKeyGenerator(I2PAppContext context)
Method Detail

getModData

public byte[] getModData()
The current (today's) mod data. Warning - not a copy, do not corrupt.

Returns:
non-null, 8 bytes

getNextModData

public byte[] getNextModData()
Tomorrow's mod data. Warning - not a copy, do not corrupt. For debugging use only.

Returns:
non-null, 8 bytes
Since:
0.9.10

getLastChanged

public long getLastChanged()
Description copied from class: RoutingKeyGenerator
The version of the current (today's) mod data. Use to determine if the routing key should be regenerated.

Specified by:
getLastChanged in class RoutingKeyGenerator

getTimeTillMidnight

public long getTimeTillMidnight()
How long until midnight (ms)

Returns:
could be slightly negative
Since:
0.9.10 moved from UpdateRoutingKeyModifierJob

generateDateBasedModData

public boolean generateDateBasedModData()
Update the current modifier data with some bytes derived from the current date (yyyyMMdd in GMT)

Returns:
true if changed

getRoutingKey

public Hash getRoutingKey(Hash origKey)
Generate a modified (yet consistent) hash from the origKey by generating the SHA256 of the targetKey with the current modData appended to it This makes Sybil's job a lot harder, as she needs to essentially take over the whole keyspace.

Specified by:
getRoutingKey in class RoutingKeyGenerator
Throws:
IllegalArgumentException - if origKey is null

getNextRoutingKey

public Hash getNextRoutingKey(Hash origKey)
Get the routing key using tomorrow's modData, not today's

Since:
0.9.10