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HNT Price Oracles

HNT converts to Data Credits at a rate pegged to $.00001 , and so the blockchain requires a canonical HNT/$USD price for this conversion. Beginning in June 2020, the Helium blockchain started using a system of decentralized price oracles to supply the $USD to HNT price used for on-chain for burn transactions. (This system is inspired by the Maker Foundation's Oracle usage.)

To find this price, nine oracles (this number may change in the future) periodically submit HNT/$USD prices. Once the blockchain has enough new price data, it will calculate a new HNT/$USD price that will remain valid until enough new, valid oracle inputs are submitted, triggering a new price revision.

Calculating the HNT Price

Every 10 blocks (roughly every 10 minutes) the blockchain will attempt to establish a new HNT/$USD price. To do this:

  1. The blockchain looks for recent price submissions from valid Oracles (submitted using a transaction called price_oracle_submission). A valid price submission is anything that was submitted within the last 25 hours but is older than 1 hour. This enables the blockchain to calculate a trailing 24 hour median while also having a buffer against outlier price inputs in the most recent 60 minutes.
  2. If there are enough new, valid price submissions in the 24 hour window, a new price will be calculated. For this to happen, a majority of the price Oracles need to have submitted a price in the window - ((N / 2) +1 ). So, in our system of 9 Oracles, we would need valid prices from at least 5. (If there aren’t ((N / 2) +1 ) new prices, no new HNT price is calculated.)
  3. If there are at least 5 new prices, we then proceed to sort-order the list low to high, and take the median. So, if we had 7 valid submissions of $.20, $.22, $.235, $.238, $.25, $.27, $.45, the blockchain would select $.238, and use this as the external price of HNT for all HNT / DC burn transactions until a new price is established (which could be as soon as 10 blocks).

What's the current HNT Oracle Price?

Who are the HNT Price Oracles?

The HNT Oracle price feeds are supplied by a group of eleven (11) Oracles, composed of companies, organizations, and individuals. They are:

  • Helium Foundation
  • Nova Labs
  • Nine (9) Anonymous Individual Community Members

We’ve chosen to keep the names of the individual feed contributors anonymous as it’s essential to prevent any external attempts at extortion or blackmail. The names of large companies and organizations that supply feeds, however, are public and it’s easier for them to combat potential attacks and bad actors.

The current set of public keys for the eleven HNT Price Oracles are (in no particular order):

13CFFcmPtMvNQCpWQRXCTqXPnXtcsibDWVwiQRKpUCt4nqtF7RE
1431WVQvoV7RAJpoLCaBrTKner1Soed4bk69DddcrHUTCWHV6pj
136n9BEbreGUNgXJWtyzkBQcXiNzdMQ5GBoP8L2J6ZReFUAwUjy
14sqAYg1qxzjKTtyHLYZdH6yDtA3KgyoARhWN1cvLZ94dZw5vEc
145J6Aye86pKTJrUHREiXu7qqppZBcWY1bvWo8id7ZjxyuainYj
14EzXp4i1xYA7SNyim6R4J5aXN1yHYKNiPrrJ2WEvoDnxmLgaCg
147yRbowD1krUCC1DhhSMhpFEqnkwb26mHBow5nk9q43AakSHNA
13ZGgWX4Ajz9g9t3tM9ohDyso12o2E2CpYbMF2RBaT93rj7souE
1489qpKWAoLrURcaQEM1wJEViD4mk9WcqZMGhiTFfNGmaz8NFdX
14hntpRicek9pxzHBDPVWPwYHHmExrksaxzAsTjjstgLfnfG5Ve
14aQaRARuwLTLHLygiDNNapKZ7bcLSyXhHq9DeZ5kB2dnCxiiKv

You can list activity for a specific Oracle at:

https://api.helium.io/v1/oracle/:address/activity

Submitting an HNT Oracle Price

An HNT price will only be accepted if the transaction is signed by the private key associated with one of the known oracle public keys listed above.

Required Software

Currently Oracles use the Helium Wallet CLI for submitting prices to the blockchain. Download this and get comfortable with it on your machine if you're not using it already.

Submitting HNT Prices

We've added a new transaction to the blockchain for Oracle price submissions - price_oracle_submission, and a corresponding CLI command - oracle report.

When you download the CLI and run helium-wallet oracle report --help, you'll see something like this:

helium-wallet-oracle-report
Construct an oracle price report and optionally commit it to the Helium Blockchain

USAGE:
    helium-wallet oracle report [FLAGS] --block <block> --price <price>

FLAGS:
        --commit     Commit the oracle price report to the API
    -h, --help       Prints help information
    -V, --version    Prints version information

OPTIONS:
        --block <block>    Block height to report the price at. Use "auto" to pick the latest known block height from
                           the API
        --price <price>    The oracle price to report. Specify in USD or supply one of the supported price lookup
                           services ("coingecko", "bilaxy")

Example Command

Here's a full command to submit a price (with the leading $ the command line will supply). Note the required --commit flag. This transaction will fail without this.

$ helium-wallet oracle report --price 1.1 --block auto --commit

This is telling the blockchain you are reporting a price of $1.1 and the current block height and that you're ready to commit it.

Once you hit Return, you'll be asked to input your wallet key passphrase. Supply this, submit it, and you're done.

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