From 25fbc04ed4909e90e7318be4ab5f1ca19b68ac39 Mon Sep 17 00:00:00 2001
From: Magnus Ahltorp <map@kth.se>
Date: Mon, 2 Mar 2015 11:32:03 +0100
Subject: Split reading of private and public keyfile

---
 src/sign.erl | 43 +++++++++++++++----------------------------
 1 file changed, 15 insertions(+), 28 deletions(-)

diff --git a/src/sign.erl b/src/sign.erl
index 2c4441b..9acb9d4 100644
--- a/src/sign.erl
+++ b/src/sign.erl
@@ -11,7 +11,7 @@
 -export([sign/1, get_pubkey/0, get_logid/0]).
 -export([read_keyfile_ec/1]).
 %% API for tests.
--export([read_keyfile_rsa/2, read_keyfiles_ec/2]).
+-export([read_keyfile_rsa/2]).
 %% gen_server callbacks.
 -export([init/1, handle_call/3, terminate/2,
          handle_cast/2, handle_info/2, code_change/3]).
@@ -41,7 +41,9 @@ init([]) ->
     %% Read EC keypair.
     PrivKeyfile = application:get_env(plop, log_private_key, none),
     PubKeyfile = application:get_env(plop, log_public_key, none),
-    {Private_key, Public_key, LogID} = read_keyfiles_ec(PrivKeyfile, PubKeyfile),
+    Private_key = read_keyfile_ec(PrivKeyfile),
+    Public_key = read_keyfile_ec(PubKeyfile),
+    LogID = read_keyfile_ec_logid(PubKeyfile),
     _Tree = ht:reset_tree([db:size() - 1]),
     {ok, #state{pubkey = Public_key,
                 privkey = Private_key,
@@ -55,12 +57,22 @@ read_keyfile_rsa(Filename, Passphrase) ->
     Privatekey = decode_key(KeyPem, Passphrase),
     {Privatekey, public_key(Privatekey)}.
 
+filter_pem_types(ParsedPem, Types) ->
+    [E || E <- ParsedPem,
+          lists:member(element(1, E), Types)].
+
 read_keyfile_ec(KeyFile) ->
     lager:debug("reading file ~p", [KeyFile]),
     {ok, PemBin} = file:read_file(KeyFile),
-    [KeyPem] = public_key:pem_decode(PemBin),
+    [KeyPem] = filter_pem_types(public_key:pem_decode(PemBin), ['ECPrivateKey', 'SubjectPublicKeyInfo']),
     decode_key(KeyPem).
 
+read_keyfile_ec_logid(KeyFile) ->
+    lager:debug("reading file ~p", [KeyFile]),
+    {ok, PemBin} = file:read_file(KeyFile),
+    [{'SubjectPublicKeyInfo', Der, _}] = filter_pem_types(public_key:pem_decode(PemBin), ['SubjectPublicKeyInfo']),
+    crypto:hash(sha256, Der).
+
 pem_entry_decode({'SubjectPublicKeyInfo', Der, _}) ->
     SPKI = public_key:der_decode('SubjectPublicKeyInfo', Der),
     #'SubjectPublicKeyInfo'{subjectPublicKey = {_, Octets},
@@ -72,31 +84,6 @@ pem_entry_decode({'SubjectPublicKeyInfo', Der, _}) ->
 pem_entry_decode(Entry) ->
     public_key:pem_entry_decode(Entry).
 
-%% @doc Read two PEM files, one with a private EC key and one with the
-%% corresponding public EC key.
-read_keyfiles_ec(PrivkeyFile, Pubkeyfile) ->
-    {ok, PemBinPriv} = file:read_file(PrivkeyFile),
-    [OTPPubParamsPem, PrivkeyPem] = public_key:pem_decode(PemBinPriv),
-    Privatekey = decode_key(PrivkeyPem),
-
-    {_, ParamsBin, ParamsEnc} = OTPPubParamsPem,
-    PubParamsPem = {'EcpkParameters', ParamsBin, ParamsEnc},
-    Params = public_key:pem_entry_decode(PubParamsPem),
-
-    {ok, PemBinPub} = file:read_file(Pubkeyfile),
-    [SPKIPem] = public_key:pem_decode(PemBinPub),
-    %% SPKI is missing #'AlgorithmIdentifier' so pem_entry_decode won't do.
-    %% Publickey = public_key:pem_entry_decode(SPKIPem),
-    #'SubjectPublicKeyInfo'{algorithm = AlgoDer} = SPKIPem,
-    SPKI = public_key:der_decode('SubjectPublicKeyInfo', AlgoDer),
-    #'SubjectPublicKeyInfo'{subjectPublicKey = {_, Octets}} = SPKI,
-    Point = #'ECPoint'{point = Octets},
-    Publickey = {Point, Params},
-
-    KeyID = crypto:hash(sha256, AlgoDer),
-
-    {Privatekey, Publickey, KeyID}.
-
 %% -spec signhash_rsa(iolist() | binary(), public_key:rsa_private_key()) -> binary().
 %% signhash_rsa(Data, PrivKey) ->
 %%     %% Was going to just crypto:sign/3 the hash but looking at
-- 
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