DFINITY Foundation

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ysyms

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Krzysztof Żelazko

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Jerry Banfield

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ZenithCode

Aviate Labs

# Rebootstrap the Bitcoin Testnet Canister

## Summary

This is a second attempt of the [previous](https://dashboard.internetcomputer.org/proposal/133186)
proposal which failed due to the uploader Wasm being bigger than the allowed limit of
cross-subnet inter-canister calls.

The Bitcoin testnet often suffers from "block storms" where the block rate
rises sharply due to difficulty resets. A recent "block storm" was severe
enough creating multiple temporary forks and the canister started following
the wrong fork. This was also partially due to a lower stability threshold
which was tuned to help with some past issues we've seen (those issues have
since been resolved, so the stability threshold can be increased again).

Given that the canister is stuck on a wrong fork, the way out is to rebootstrap
the canister using a higher stability threshold to ensure that it will follow
the main chain.

There will be two proposals to rebootstrap the Bitcoin testnet canister:

1. (This one) A proposal to install an `uploader` canister, replacing the
   current Bitcoin testnet canister. The `uploader` canister is pre-configured
   to only accept the Bitcoin testnet state that has been computed offline.
   *The Bitcoin testnet canister will be unavailable during this time.*

2. A proposal to upgrade the `uploader` canister into the Bitcoin canister,
   which will then be initialized with Bitcoin testnet state up to height
   2982190 and will resume syncing from there.

Rebootstrapping the canister such that it starts syncing from height 2982190
rather than from genesis reduces the downtime significantly. The expected
downtime will be ~2 days with this approach, whereas syncing from genesis
will require a downtime of around four weeks.

## Verification Steps

### Wasm Verification

NOTE: The verification scripts can take more than 24 hours and need > 400 GiB of disk
space. The hashes are also not guaranteed to match on Apple Silicon.

```shell
# Clone the bitcoin-canister repo.
$ git clone git@github.com:dfinity/bitcoin-canister.git
$ cd bitcoin-canister
$ git checkout f029854e477d62e925096c63873bbf0d0ceab136
$ cd bootstrap # move to the bootstrap directory
```

Follow the instructions in `./bootstrap/README.md`, using the following values
for the environment variables:

```
BITCOIN_DIR=<path/to/bitcoin-22>
HEIGHT=2982190
STABILITY_THRESHOLD=144
NETWORK=testnet
```

By the end of the process, you'll have generated the file `bootstrap/chunk_hashes.txt` with the following checksum:

```
6ac58440e6980a1df00e0f81707db2868f1913abfaaeb2d0f7e698cefbbd389d  chunk_hashes.txt
```

In case of a checksum mismatch, the following are checksums of intermediate files to help with debugging:

In the `./bootstrap` directory:

```
1b24f53d2c305d79499b1d8b257842527778c8229b58ffe1568b3c3970e0ccad  unstable_blocks
50a72942bf29c373a3c4fae043b29367fe01d079de772dac92e483221143a6be  block_headers
65339026ac4fc4811e64bf07fda60a56181fcfc7c4b050e66475c59ead56389d  utxodump.csv
81aa24b5b76b6bdb51b835df6d7dd4960cd51a1f5c7afc54e0e11aa7be8692fe  utxodump_shuffled.csv
037bee16b825b9c96575e34b1307c893f3a3cf85f3039b04cef7479ce3465826  canister_state.bin
```

In the `./bootstrap/canister_state` directory:

```
6911f4d3036205736b06a9f7ce93b1b951df957eeb18d95d3836589a15b7d47d  address_utxos
402abe060c7323ee0c2ef8c04fa94791413e2f25df876bdd6a36ed614d0942ba  balances
aaf5b4b76fefcfb4337088f686853bdfa2ffa24ff5a699740415d39346906d2c  large_utxos
2c53f66bc38dad1f0d8e029369865c177f9d8e41bb8e316d899a4ac6d044a162  medium_utxos
717c2e18fec87e49778c6115d23b38bc26ecd4faccb7f724e7472d8993e15325  small_utxos
```

The main difference compared to the previous proposal is the following [fix](https://github.com/dfinity/bitcoin-canister/commit/708eb8bcf46d36ad70d24f7effc7a390ab655228)
which optimizes the size of the uploader Wasm binary.

Build the uploader canister, which incorporates `chunk_hashes.txt` into the binary:

```shell
# From the root of the repository.

# Ensure you are on the right commit to pick up the fix
$ git checkout 708eb8bcf46d36ad70d24f7effc7a390ab655228

# Build all, specifying the path to chunk_hashes.txt
$ docker build --build-arg CHUNK_HASHES_PATH=/bootstrap/chunk_hashes.txt  -t canisters .

# Extract canister's wasm.
$ docker run --rm --entrypoint cat canisters /uploader.wasm.gz > uploader.wasm.gz

# Calculate SHA-256 of the canister's wasm.
$ sha256sum uploader.wasm.gz
```

You should then see the following output:

```shell
65725a5c8967134aee467f80d2fd9e54af8246a50da28bbc8a01900b9f728398 uploader.wasm.gz
```

### Upgrade arguments verification

The uploader canister is initialized with the size of the state to be uploaded in Wasm pages. The size of canister_state.bin should be 1591041 Wasm pages.

```shell
$ didc encode -t '(nat64)' "(1591041)" | xxd -r -p | sha256sum
```

Expected output:

```shell
0c10580b21ccbac21c5d625e9bed8fa33ea0cad5fede0abf2c7f3b5a5e4cecc9
```


Upgrade NNS Canister: g4xu7-jiaaa-aaaan-aaaaq-cai to wasm with hash: 65725a5c8967134aee467f80d2fd9e54af8246a50da28bbc8a01900b9f728398