Derive token policy forging keys according to CIP-1855

lib/core/cardano-wallet-core.cabal

@@ -167,6 +167,7 @@ library
  Cardano.Wallet.Primitive.AddressDerivation
  Cardano.Wallet.Primitive.AddressDerivation.Byron
  Cardano.Wallet.Primitive.AddressDerivation.Icarus
+ Cardano.Wallet.Primitive.AddressDerivation.MintBurn
  Cardano.Wallet.Primitive.AddressDerivation.Shared
  Cardano.Wallet.Primitive.AddressDerivation.SharedKey
  Cardano.Wallet.Primitive.AddressDerivation.Shelley
@@ -359,6 +360,7 @@ test-suite unit
  Cardano.Wallet.NetworkSpec
  Cardano.Wallet.Primitive.AddressDerivation.ByronSpec
  Cardano.Wallet.Primitive.AddressDerivation.IcarusSpec
+ Cardano.Wallet.Primitive.AddressDerivation.MintBurnSpec
  Cardano.Wallet.Primitive.AddressDerivationSpec
  Cardano.Wallet.Primitive.AddressDiscovery.RandomSpec
  Cardano.Wallet.Primitive.AddressDiscovery.SequentialSpec

lib/core/src/Cardano/Wallet/Primitive/AddressDerivation.hs

@@ -46,6 +46,7 @@ module Cardano.Wallet.Primitive.AddressDerivation
  , DerivationPrefix (..)
  , DerivationIndex (..)
  , liftIndex
+ , hashVerificationKey
 
  -- * Delegation
  , RewardAccount (..)
@@ -85,7 +86,7 @@ module Cardano.Wallet.Primitive.AddressDerivation
 import Prelude
 
 import Cardano.Address.Derivation
- ( XPrv, XPub )
+ ( XPrv, XPub, xpubPublicKey )
 import Cardano.Mnemonic
  ( SomeMnemonic )
 import Cardano.Wallet.Primitive.Types
@@ -103,7 +104,7 @@ import Control.Monad
 import Crypto.Hash
  ( Digest, HashAlgorithm )
 import Crypto.Hash.Utils
- ( blake2b256 )
+ ( blake2b224, blake2b256 )
 import Crypto.KDF.PBKDF2
  ( Parameters (..), fastPBKDF2_SHA512 )
 import Crypto.Random.Types
@@ -151,6 +152,8 @@ import Quiet
 import Safe
  ( readMay, toEnumMay )
 
+import Cardano.Address.Script
+ ( KeyHash (KeyHash), KeyRole )
 import qualified Codec.CBOR.Encoding as CBOR
 import qualified Codec.CBOR.Write as CBOR
 import qualified Crypto.Scrypt as Scrypt
@@ -163,11 +166,28 @@ import qualified Data.Text.Encoding as T
  HD Hierarchy
 -------------------------------------------------------------------------------}
 
--- | Key Depth in the derivation path, according to BIP-0044 / CIP-1852
+-- | Typically used as a phantom type parameter, a witness to the type of the
+-- key being used.
+--
+-- For example, @key 'RootK XPrv@, represents the private key at the root of the
+-- HD hierarchy.
+--
+-- According to BIP-0044 / CIP-1852, we have the following keys in our HD
+-- hierarchy:
 --
 -- @m | purpose' | cointype' | account' | role | address@
+--
+-- Plus, we also have script keys (which are used in shared wallets) and policy
+-- keys (which are used in minting and burning).
 data Depth
- = RootK | PurposeK | CoinTypeK | AccountK | RoleK | AddressK | ScriptK
+ = RootK
+ | PurposeK
+ | CoinTypeK
+ | AccountK
+ | RoleK
+ | AddressK
+ | ScriptK
+ | PolicyK
 
 -- | Marker for addresses type engaged. We want to handle four cases here.
 -- The first two are pertinent to UTxO accounting,
@@ -492,6 +512,14 @@ deriveRewardAccount pwd rootPrv =
  let accPrv = deriveAccountPrivateKey pwd rootPrv minBound
  in deriveAddressPrivateKey pwd accPrv MutableAccount minBound
 
+hashVerificationKey
+ :: WalletKey key
+ => KeyRole
+ -> key depth XPub
+ -> KeyHash
+hashVerificationKey keyRole =
+ KeyHash keyRole . blake2b224 . xpubPublicKey . getRawKey
+
 {-------------------------------------------------------------------------------
  Passphrases
 -------------------------------------------------------------------------------}

lib/core/src/Cardano/Wallet/Primitive/AddressDerivation/MintBurn.hs

@@ -0,0 +1,100 @@
+{-# LANGUAGE DataKinds #-}
+
+-- |
+-- Copyright: © 2018-2021 IOHK
+-- License: Apache-2.0
+--
+-- Derivation of policy keys which are used to create scripts for the purposes
+-- of minting and burning. Derived according to CIP-1855
+-- (https:/cardano-foundation/CIPs/blob/b2e9d02cb9a71ba9e754a432c78197428abf7e4c/CIP-1855/CIP-1855.md).
+--
+-- The policy keys are derived from the following path:
+--
+-- m / purpose' / coin_type' / policy_ix'
+-- m / 1855' / 1815' / [2^31 .. 2^32-1]'
+--
+-- Where purpose' and coin_type' are fixed, and each new policy_ix' represents a
+-- different policy key.
+
+module Cardano.Wallet.Primitive.AddressDerivation.MintBurn
+ ( -- * Constants
+ purposeCIP1855
+ -- * Helpers
+ , derivePolicyKeyAndHash
+ , derivePolicyPrivateKey
+ ) where
+
+import Prelude
+
+import Cardano.Address.Derivation
+ ( XPrv )
+import Cardano.Address.Script
+ ( KeyHash )
+import Cardano.Crypto.Wallet
+ ( deriveXPrv )
+import Cardano.Crypto.Wallet.Types
+ ( DerivationScheme (DerivationScheme2) )
+import Cardano.Wallet.Primitive.AddressDerivation
+ ( Depth (..)
+ , DerivationType (..)
+ , Index (..)
+ , Passphrase (..)
+ , WalletKey
+ , getIndex
+ , getRawKey
+ , hashVerificationKey
+ , liftRawKey
+ , publicKey
+ )
+import Cardano.Wallet.Primitive.AddressDiscovery
+ ( coinTypeAda )
+
+import qualified Cardano.Address.Script as CA
+
+-- | Purpose for forged policy keys is a constant set to 1855' (or 0x8000073F)
+-- following the original CIP-1855: "Forging policy keys for HD Wallets".
+--
+-- It indicates that the subtree of this node is used according to this
+-- specification.
+--
+-- Hardened derivation is used at this level.
+purposeCIP1855 :: Index 'Hardened 'PurposeK
+purposeCIP1855 = toEnum 0x8000073F
+
+-- | Derive the policy private key that should be used to create mint/burn
+-- scripts.
+derivePolicyPrivateKey
+ :: Passphrase purpose
+ -- ^ Passphrase for wallet
+ -> XPrv
+ -- ^ Root private key to derive policy private key from
+ -> Index 'Hardened 'PolicyK
+ -- ^ Index of policy script
+ -> XPrv
+ -- ^ Policy private key
+derivePolicyPrivateKey (Passphrase pwd) rootXPrv (Index policyIx) =
+ let
+ purposeXPrv = -- lvl1 derivation; hardened derivation of purpose'
+ deriveXPrv DerivationScheme2 pwd rootXPrv (getIndex purposeCIP1855)
+ coinTypeXPrv = -- lvl2 derivation; hardened derivation of coin_type'
+ deriveXPrv DerivationScheme2 pwd purposeXPrv (getIndex coinTypeAda)
+ -- lvl3 derivation; hardened derivation of policy' index
+ in deriveXPrv DerivationScheme2 pwd coinTypeXPrv policyIx
+
+-- | Derive the policy private key that should be used to create mint/burn
+-- scripts, as well as the key hash of the policy public key.
+derivePolicyKeyAndHash
+ :: WalletKey key
+ => Passphrase "encryption"
+ -- ^ Passphrase for wallet
+ -> key 'RootK XPrv
+ -- ^ Root private key to derive policy private key from
+ -> Index 'Hardened 'PolicyK
+ -- ^ Index of policy script
+ -> (key 'PolicyK XPrv, KeyHash)
+ -- ^ Policy private key
+derivePolicyKeyAndHash pwd rootPrv policyIx = (policyK, vkeyHash)
+ where
+ policyK = liftRawKey policyPrv
+ policyPrv = derivePolicyPrivateKey pwd (getRawKey rootPrv) policyIx
+ vkeyHash = hashVerificationKey CA.Payment (publicKey policyK)