diff --git a/tools/offline_bin.ml b/tools/offline_bin.ml
index 1919706d..ee9b4201 100644
--- a/tools/offline_bin.ml
+++ b/tools/offline_bin.ml
@@ -2,6 +2,47 @@ open Crypto
 open Bin_type
 open Api
 
+module Verify_sigs = struct
+  let future_denom
+    FutureDenom.
+      {
+        section_name= _;
+        value;
+        stamp_start;
+        stamp_expire_withdraw;
+        stamp_expire_deposit;
+        stamp_expire_legal;
+        denom_pub;
+        fee_withdraw;
+        fee_deposit;
+        fee_refresh;
+        fee_refund= _;
+        denom_secmod_sig= _;
+      } =
+  let octets = DenominationKey.to_octets denom_pub in
+  let h_denom_pub = HashCode.hash octets in
+  let master_sig =
+    let open Bin_signature.DenominationKeyValidityPS in
+    let master = EddsaPrivateKey.(pub_of_priv master_key) in
+    let denom_hash = DenominationHash.hash octets in
+    {
+      master;
+      start= stamp_start;
+      expire_withdraw= stamp_expire_withdraw;
+      expire_spend= stamp_expire_deposit;
+      expire_legal= stamp_expire_legal;
+      value;
+      fee_withdraw;
+      fee_deposit;
+      fee_refresh;
+      denom_hash;
+    }
+    |> Bin.to_string bin
+    |> EddsaSignature.sign ~key:master_key
+  in
+  DenomSignature.{ h_denom_pub; master_sig }
+end
+
 let denom_signature ~master_key
     FutureDenom.
       {