From e394689e748ac582c6b4556e41556137c583b21a Mon Sep 17 00:00:00 2001
From: Hans Nilsson <hans@erlang.org>
Date: Tue, 31 Oct 2017 15:31:47 +0100
Subject: crypto: Add privkey_to_pubkey/2 to get the public key from a priv key
 in an Engine Only RSA and DSA so far.

---
 lib/crypto/src/crypto.erl | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

(limited to 'lib/crypto/src')

diff --git a/lib/crypto/src/crypto.erl b/lib/crypto/src/crypto.erl
index 7510babdde..0d39dcc76e 100644
--- a/lib/crypto/src/crypto.erl
+++ b/lib/crypto/src/crypto.erl
@@ -42,6 +42,7 @@
 -export([public_encrypt/4, private_decrypt/4]).
 -export([private_encrypt/4, public_decrypt/4]).
 -export([dh_generate_parameters/2, dh_check/1]). %% Testing see
+-export([privkey_to_pubkey/2]).
 -export([ec_curve/1, ec_curves/0]).
 -export([rand_seed/1]).
 %% Engine
@@ -1058,6 +1059,16 @@ ec_curves() ->
 ec_curve(X) ->
     crypto_ec_curves:curve(X).
 
+
+privkey_to_pubkey(Alg, EngineMap) when Alg == rsa; Alg == dss; Alg == ecdsa ->
+    case privkey_to_pubkey_nif(Alg, format_pkey(Alg,EngineMap)) of
+        [_|_]=L -> map_ensure_bin_as_int(L);
+        X -> X
+    end.
+            
+privkey_to_pubkey_nif(_Alg, _EngineMap) -> ?nif_stub.
+
+
 %%
 %% EC
 %%
@@ -1125,6 +1136,14 @@ ensure_int_as_bin(Int) when is_integer(Int) ->
 ensure_int_as_bin(Bin) ->
     Bin.
 
+map_ensure_bin_as_int(List) when is_list(List) ->
+    lists:map(fun ensure_bin_as_int/1, List).
+
+ensure_bin_as_int(Bin) when is_binary(Bin) ->
+    bin_to_int(Bin);
+ensure_bin_as_int(E) ->
+    E.
+
 format_pkey(_Alg, #{engine:=_, key_id:=T}=M) when is_binary(T) -> format_pwd(M);
 format_pkey(_Alg, #{engine:=_, key_id:=T}=M) when is_list(T) -> format_pwd(M#{key_id:=list_to_binary(T)});
 format_pkey(_Alg, #{engine:=_           }=M) -> error({bad_key_id, M});
-- 
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