From 3fe02217a185bc76eef917b7af479f39fb07d90a Mon Sep 17 00:00:00 2001
From: Neil Mayhew <neil.mayhew@iohk.io>
Date: Tue, 3 Dec 2024 08:11:23 -0700
Subject: [PATCH] Add functions to convert hashes to and from VRFVerKeyHash

---
 libs/cardano-ledger-core/CHANGELOG.md                |  1 +
 .../src/Cardano/Ledger/Keys/Internal.hs              | 12 +++++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/libs/cardano-ledger-core/CHANGELOG.md b/libs/cardano-ledger-core/CHANGELOG.md
index aff58b96c61..e2629e42497 100644
--- a/libs/cardano-ledger-core/CHANGELOG.md
+++ b/libs/cardano-ledger-core/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## 1.16.0.0
 
+* Add `toVRFVerKeyHash` and `fromVRFVerKeyHash`
 * Change lens type of `hkdNOptL`, `ppNOptL`, and `ppuNOptL` to `Word16`
 * Add `epochFromSlot`
 * Remove usage of a `Reader` monad in `epochInfoEpoch`, `epochInfoFirst` and `epochInfoSize`.
diff --git a/libs/cardano-ledger-core/src/Cardano/Ledger/Keys/Internal.hs b/libs/cardano-ledger-core/src/Cardano/Ledger/Keys/Internal.hs
index 8090fa12811..c6943b5bc1a 100644
--- a/libs/cardano-ledger-core/src/Cardano/Ledger/Keys/Internal.hs
+++ b/libs/cardano-ledger-core/src/Cardano/Ledger/Keys/Internal.hs
@@ -35,6 +35,8 @@ module Cardano.Ledger.Keys.Internal (
   KeyRoleVRF (..),
   VRFVerKeyHash (..),
   hashVerKeyVRF,
+  toVRFVerKeyHash,
+  fromVRFVerKeyHash,
 
   -- * Genesis delegations
   GenDelegPair (..),
@@ -373,4 +375,12 @@ deriving newtype instance Crypto c => Default (VRFVerKeyHash r c)
 
 hashVerKeyVRF ::
   Crypto c => VerKeyVRF c -> VRFVerKeyHash (r :: KeyRoleVRF) c
-hashVerKeyVRF = VRFVerKeyHash . Hash.castHash . VRF.hashVerKeyVRF
+hashVerKeyVRF = toVRFVerKeyHash . VRF.hashVerKeyVRF
+
+toVRFVerKeyHash ::
+  Hash.Hash (HASH c) (VRF.VerKeyVRF v) -> VRFVerKeyHash (r :: KeyRoleVRF) c
+toVRFVerKeyHash = VRFVerKeyHash . Hash.castHash
+
+fromVRFVerKeyHash ::
+  VRFVerKeyHash (r :: KeyRoleVRF) c -> Hash.Hash (HASH c) (VRF.VerKeyVRF v)
+fromVRFVerKeyHash = Hash.castHash . unVRFVerKeyHash