When you want to perform some test/auditing against the IOTA Reference implementation (IRI), you probably want to test your assumptions against your own testnet (for some scenarios one node is enough, other require more nodes). Using the public testnet has the disadvantage that you are not alone on your tangle, so somebody else might confirm your transactions you like to stay unconfirmed, or breakpoints you add inside IRI can trigger by transactions done by others thyn you. Currently you will face some obstacles when trying to do so:
- The official wallet will not connect to any node which has not received at least one milestone from the coordinator
- As IOTA is not mineable, your accounts will start with 0 IOTA, and you cannot change this by mining some
To get around these obstacles, you need to perform these steps
- Build your own Snapshot.txt and recompile IRI to use it
- Once your recompiled IRI is started (or later whenever you want the milestone index to increase), run a testnet coordinator that will create a new milestone for you
This repository contains tools (written in Java) to build your own Snapshot and to run a coordinator once to create a new milestone.
Get and compile this (private-iota-testnet) repository
mvn package
In case you are on Windows and your build process freezes at that point, this may be caused by a bug in Maven when repacking the signed BouncyCastle jar file. To work around it, you can open %USERPROFILE%\.m2\repository\org\bouncycastle\bcprov-jdk15on\1.58\bcprov-jdk15on-1.58.jar with a zip program and remove the signature files inside its META-INF directory (they are not needed for iota or iri to work), then rebuild.
Now it is time to build your own Snapshot. First decide how you want to split the 2 779 530 283 277 761 available IOTA to addresses, and which of them should belong to the same wallet.
Then start the interactive process:
java -jar target/iota-testnet-tools-0.1-SNAPSHOT-jar-with-dependencies.jar SnapshotBuilder
It will ask you about the IOTA you want to assign (you can also use suffixes like Gi or Pi). Once you have assigned all IOTA, it will write a Snapshot.txt (to be compiled into iri) and a Snapshot.log (for you to remember the seeds to the addresses).
Get iri if you do not already have it.
Copy Snapshot.txt to iri/src/main/resources.
Comment out the part that validates the snapshot signature. It would also be possible to recreate the signature with a different signing key, but then you have to replace the signing key in the source code instead. So I think it is not worth the hassle and just decided to comment out the signature verification (The nodes will be only used by yourself, won't they?).
Compile and run iri as usual. When starting iri, make sure to include the --testnet switch, and that the current directory does not contain any testnetdb files from previous runs.
java -jar iri.jar --testnet -p 14700
Before you can connect to your iri with your wallet, you need to run the coordinator to create the first milestone
java -jar target/iota-testnet-tools-0.1-SNAPSHOT-jar-with-dependencies.jar Coordinator localhost 14700
After that you can use your wallet, log into one of your seeds, and attach addresses until you see your full balance.
In case you want a new milestone, just run the coordinator again.
Have fun!
Testnet by default requires PoW for minWeightMagnitude=13. When performing larger scale tests, you might want to decrease this. To do so, you will have to
patch iri at two places and recompile it. To build the package use mvn package -Dmaven.test.skip=true to prevent that tests will terminate the building process; also be aware that the UDP protocol between neighbors will break as the packets are not big enough to hold the full transaction hash if the hash does not end with a sufficient amount of zeroes (so best test with only a single isolated node).
When using the official wallet, you also have to patch this. If you (like me) have trouble recompiling the Windows wallet, you can instead patch it in-place. Have a look at AppData\Local\Programs\iota\resources\ui\js\ui.update.js (search for connection.minWeightMagnitude) and AppData\Local\Programs\iota\resources\app.asar (search for var minWeightMagnitudeMinimum). Note that the second file is a binary file, so when patching it make sure not to destroy any control characters (use a hex editor or an editor like Notepad++ that can keep them intact), and to keep the file size the same. Custom code usually passes the minWeightMagnitude as a parameter anyway.
In most cases, however, it is enough to make sure you use minWeightMagnitude=13 instead of 14 and it will be "fast enough".
iri uses Merkle-Winternitz signatures to sign snapshots and milestones, using CurlP27 and CurlP81 hash function, respectively. As the Merkle hash tree for the milestons is rather large (1048576 subkeys) and generation can take a while, this project provides a way to compute partial Merkle hash trees where only some indices (e. g. 243000 to 243100) are filled. This makes generation much faster, while still allowing to test signature verification in real-life conditions.
If you want to go that route, you need to change the Coordinator address and the Snapshot signing public key in the iri source before recompiling. You may also need to enable milestone signature verification when you are using testnet configuration otherwise.
Generate key files for snapshots and milestones:
java -cp target/iota-testnet-tools-0.1-SNAPSHOT-jar-with-dependencies.jar iotatools.KeyfileBuilder Snapshot.key 3 CURLP81 6 1 3
java -cp target/iota-testnet-tools-0.1-SNAPSHOT-jar-with-dependencies.jar iotatools.KeyfileBuilder Coordinator.key 1 CURLP27 20 243000 100
The keyfile parameters are security (3 for snapshot, 1 for milestones), hash algorithm, Merkle tree depth, and optionally first used key and number of keys (to make generation faster). The pubkey is printed on the console and also in the last line of the key file.
Signing a snapshot:
java -cp target/iota-testnet-tools-0.1-SNAPSHOT-jar-with-dependencies.jar iotatools.SnapshotSigner Snapshot.key 1
Creating a signed milestone:
java -cp target/iota-testnet-tools-0.1-SNAPSHOT-jar-with-dependencies.jar iotatools.SignedCoordinator localhost 14700
Always remember: With great power comes great responsibility - I do not want to see this repo end as the base of yet another Aidos Kuneen...