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CIP-1855

Abstract

This document describes how to derive forging policy keys used for minting/burning tokens.

Glossary

TermDefinition
HDHierarchical Deterministic, refers to wallets as described in BIP-0032.

Motivation

Overview

Forging tokens is derived from a script policy. The script policy includes hashes of keys needed to forge new tokens and must be witnessed by these keys in such a way as the script stipulates. This CIP defines the derivation path at wich parties are expected to derive such keys.

Specification

HD Derivation

We consider the following HD derivation paths similarly to CIP-1852:

m / purpose' / coin_type' / policy_ix'

To associate policy keys to a wallet, we reserve however purpose=1855' for policy keys for forging tokens. The coin type remains coin_type=1815' to identify Ada as registered in SLIP-0044. We use a hardened index for each policy key as derivation is not needed.

We can summarize the various paths and their respective domain in the following table:

purposecoin_typepolicy_ix
1855'1815'[2^31 .. 2^32-1]

CIP-0005 prefixes

To distinguish such keys & derived material in the human readable prefix of the bech32 representation, we introduce the following prefixes for insertion into CIP-0005:

Keys

PrefixMeaningContents
policy_skCIP-1855's policy private keyEd25519 private key
policy_vkCIP-1855's policy public keyEd25519 public key

Hashes

PrefixMeaningContents
policy_vkhCIP-1855's Policy verification key hashblake2b_224 digest of a policy verification key

Rationale

  • ERC20 Converter IOHK is developing needs to keep track of policy keys. Rather than having randomly generated policy keys, a policy key can be associated with a mnemonic which is easier to backup.

  • A 3rd party may want to have multiple tokens tied to same mnemonic, so we allow an index to specify the token.

  • Contrary to CIP 1852, we don't use the role and index levels of the derivation path, since index is expressed at the 3rd level and no roles for policy signing keys are currently anticipated.

  • No prefixes are defined for extended keys, since currently this CIP does not define further derivations.

  • We use a different purpose for mainly two reasons:

    • It prevents mixing up standard wallets with policy keys used for forging.

    • Using a different purpose also fits well the use-case on hardware wallets who can still rely on a single root seed to manage many types of wallets.

Examples

  • m/1855’/1815’/0’
  • m/1855’/1815’/1’
  • m/1855’/1815’/2’

Backwards Compatibility

N/A (no preceding implementation or design).

Reference Implementation

None yet.

Related Work

DescriptionLink
BIP-0032 - HD Walletshttps://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki
CIP-5 - Common Bech32 Prefixeshttps://github.com/cardano-foundation/CIPs/tree/master/CIP-0005
CIP-1852 - Cardano HD Walletshttps://github.com/cardano-foundation/CIPs/tree/master/CIP-1852
A Formal Specification of the Cardano Ledgerhttps://hydra.iohk.io/job/Cardano/cardano-ledger-specs/shelleyLedgerSpec/latest/download-by-type/doc-pdf/ledger-spec

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CIP Information

This Standards ./CIP-1855 created on 2021-06-02 has the status: Active.
This page was generated automatically from: cardano-foundation/CIPs.