diff --git a/src/api.ml b/src/api.ml
index 07355901..4f294418 100644
--- a/src/api.ml
+++ b/src/api.ml
@@ -72,27 +72,6 @@ module B32 = struct
       ~decode:B32.decode Caqti_type.string
 end
 
-(* TODO use DenominationHash directly *)
-module HashCode : sig
-  type t
-
-  val hash : string -> t
-  val of_b32 : B32.t -> (t, string) result
-  val to_denomination_hash : t -> Bin_type.DenominationHash.t
-  val jsont : t Jsont.t
-end = struct
-  type t = B32.t
-
-  let to_denomination_hash s = Bin_type.DenominationHash.of_octets s
-
-  let hash s =
-    let open Digestif.SHA512 in
-    s |> digest_string |> to_raw_string
-
-  let of_b32 = B32.decode
-  let jsont = B32.jsont
-end
-
 (* TODO error response
    - use GANA error codes
      https://git.gnunet.org/gana.git/tree/gnu-taler-error-codes/registry.rec *)
@@ -886,7 +865,7 @@ end
 
 module AuditorDenominationKey = struct
   type t = {
-    denom_pub_h: HashCode.t;
+    denom_pub_h: DenominationHash.t;
     auditor_sig: ExchangeKeyValidity.t;
   }
 
@@ -895,7 +874,7 @@ module AuditorDenominationKey = struct
     let denom_pub_h v = v.denom_pub_h in
     let auditor_sig v = v.auditor_sig in
     map ~kind:"AuditorDenominationKey" make
-    |> mem "denom_pub_h" HashCode.jsont ~enc:denom_pub_h
+    |> mem "denom_pub_h" DenominationHash.jsont ~enc:denom_pub_h
     |> mem "auditor_sig" ExchangeKeyValidity.jsont ~enc:auditor_sig
     |> finish
 end
@@ -954,13 +933,13 @@ module SignKey = struct
 end
 
 module RecoupDenoms = struct
-  type t = { h_denom_pub: HashCode.t }
+  type t = { h_denom_pub: DenominationHash.t }
 
   let jsont =
     let make h_denom_pub = { h_denom_pub } in
     let h_denom_pub v = v.h_denom_pub in
     map ~kind:"RecoupDenoms" make
-    |> mem "h_denom_pub" HashCode.jsont ~enc:h_denom_pub
+    |> mem "h_denom_pub" DenominationHash.jsont ~enc:h_denom_pub
     |> finish
 end
 
diff --git a/src/bin_type.ml b/src/bin_type.ml
index 046e3244..99a40dd0 100644
--- a/src/bin_type.ml
+++ b/src/bin_type.ml
@@ -97,6 +97,7 @@ module Hash_32 = struct
     | true -> Digestif.SHA256.of_raw_string s
 
   let to_octets = Digestif.SHA256.to_raw_string
+  let of_b32 s = Result.map of_octets (B32.decode s)
 
   let bin =
     let open Bin in
@@ -111,9 +112,8 @@ module Hash_32 = struct
       octets
 
   let jsont =
-    let dec s = Result.map of_octets (B32.decode s) in
     let enc v = B32.encode (to_octets v) in
-    Jsont.of_of_string ~kind:"Hash 32" dec ~enc
+    Jsont.of_of_string ~kind:"Hash 32" of_b32 ~enc
 end
 
 module Hash_64 = struct
@@ -132,6 +132,8 @@ module Hash_64 = struct
     | false -> Fmt.failwith "Hash.to_octets failure: data is not 64 bytes"
     | true -> s
 
+  let of_b32 s = Result.map of_octets (B32.decode s)
+
   let bin =
     let open Bin in
     map (bytes 64) of_octets to_octets
@@ -145,9 +147,8 @@ module Hash_64 = struct
       octets
 
   let jsont =
-    let dec s = Result.map of_octets (B32.decode s) in
     let enc v = B32.encode (to_octets v) in
-    Jsont.of_of_string ~kind:"Hash 64" dec ~enc
+    Jsont.of_of_string ~kind:"Hash 64" of_b32 ~enc
 end
 
 (* Hash over string + '\0' *)
@@ -176,6 +177,7 @@ module type Hash_S = sig
   val hash : string -> t
   val of_octets : string -> t
   val to_octets : t -> string
+  val of_b32 : B32.t -> (t, string) result
 end
 
 module FullPaytoHash : Hash_S = Hash_32
diff --git a/src/http_management.ml b/src/http_management.ml
index 95c63331..f24c88ff 100644
--- a/src/http_management.ml
+++ b/src/http_management.ml
@@ -236,8 +236,7 @@ module Denom_revoke = struct
     let db_conn = Vif.Server.device Devices.db_connection server in
     let sm = Vif.Server.device Devices.secmod server in
     let res =
-      let* h_denom_pub = HashCode.of_b32 h_denom_pub in
-      let h_denom_pub = HashCode.to_denomination_hash h_denom_pub in
+      let* h_denom_pub = DenominationHash.of_b32 h_denom_pub in
       let* v = Vif.Request.of_json req |> unwrap_err_msg in
       let* () = verify h_denom_pub v in
       let* () = do_ ~db_conn ~sm h_denom_pub v in
diff --git a/src/pg.ml b/src/pg.ml
index 8e9c2ae6..e942e470 100644
--- a/src/pg.ml
+++ b/src/pg.ml
@@ -220,16 +220,6 @@ let get_auditor_keys =
   fun (module Conn : CONN) () ->
     let open Syntax in
     let* l = Conn.collect_list get_auditor_keys () |> unwrap_err_caqti in
-    let* l =
-      (* TODO improve DenominationHash/HashCode situation
-         conversion here is probably bad *)
-      list_map
-        (fun (pub, url, name, denom_pub_h, auditor_sig) ->
-          let denom_pub_h = Bin_type.DenominationHash.to_octets denom_pub_h in
-          let* denom_pub_h = HashCode.of_b32 denom_pub_h in
-          Ok (pub, url, name, denom_pub_h, auditor_sig))
-        l
-    in
     let ht = Hashtbl.create 0xff in
     List.iter
       (fun (pub, url, name, denom_pub_h, auditor_sig) ->